Institutions and Specimens

The definitions of species documented here are determined from my examination of specimens stored in the following institutions: the American Museum of Natural History, New York (AMNH); Natural History Museum, London (BMNH); field number of Chris H.S. Watts, South Australian Museum, Adelaide (CHSW); field number of Lance A. Durden, Georgia Southern University, Statesboro (LAD); Museum Zoologicum Bogoriense, Cibinong, Java (MZB; now the Indonesian National Museum of Natural History; also known as the Research Center in Biology–Lembaga Ilmu Pengetahuan Indonesia); Museum of Vertebrate Zoology, Berkeley, California (MVZ); Nationaal Natuurhistorisch Museum, Leiden (RMNH); South Australian Museum, Adelaide (SAM); Staatliches Naturhistorische Sammlungen Dresden, Museum für Tierkunde (SNSD); National Museum of Natural History, Smithsonian Institution, Washington, D.C. (USNM). Specimens referenced by catalog or field number in gazetteers, tables, text, and figure captions are preceded by one of these acronyms.

Many of the generic and specific traits described here are those associated with a skin and associated skull—one of the standard museum preparations. Color descriptions of fur, ears, feet, and tail of three species (B. coelestis, B. prolatus, B. torajae, n. sp., and B. fratrorum) are derived from those museum specimens—my fieldwork never took me to the geographic regions where those species reside. Color descriptons of four other species (B. chrysocomus, B. andrewsi, B. penitus, and B. karokophilus, n. sp.) come from my field journals (stored in Mammalogy Archives, AMNH) where I recorded coloration and other details of freshly caught rats, and from the specimens themselves. My collection also includes fluid-preserved whole specimens or skinned carcasses that were initially fixed in 10% formalin, soaked for several days in water, and finally stored in 70% ethanol. I used this material to describe stomach morphology and topography of palmar and plantar surfaces, and to measure length of testes.

Measurements

Values for external dimensions are from two groups of specimens. One consists of samples I collected in central Sulawesi. For each of these specimens I measured total length; length of tail (LT), as well as length of the distal white tail tip (LWT); length of hind foot, including the claw (LHF); and length of ear, from notch to crown (LE). I took these measurements soon after the rat was caught, and also weighed it at that time to obtain a value for body mass or weight (WT, in grams).

The second group contains specimens in museums obtained and prepared by other collectors. They recorded total length, length of tail, length of hind foot, sometimes length of ear, but rarely weight. I used their value for length of tail, and measured length of the distal white tail segment on the dry study skin. I often ignored any value for length of ear because I did not know how preparators measured that dimension, and did not use collector's value for length of hind foot but measured that distance (including claws) myself on the dry skin. I also did not use total length from either group in any analyses, but subtracted length of tail from it to obtain a value for length of head and body (LHB).

In the laboratory, several measurements were made on specimens from both groups. I counted number of scale rings per centimeter (TSR/CM) on the tail about one-third the distance from its base. To measure lengths of overfur and guard hairs on the dorsum, I placed a ruler at a right angle to the skin surface on the back near the rump and recorded the approximate mark where ends of the bunched hairs rested; the technique is unsophisticated and the results imprecise, but provides a descriptive estimate of lengths for those pelage constituents.

Using dial calipers graduated to tenths of a millimeter, I measured the following cranial and dental dimensions; limits of most are illustrated in figure 2 (measurements are identified by acronyms in tables and ratio diagrams):

Age and Sex

I could consistently sort specimens into one of five relative age groups: (1) old adult (body size among the largest in a sample, clothed in full adult pelage, molars worn nearly to tops of roots so cusps are obliterated or nearly so, the crowns usually worn into shallow basins); (2) adult (body size among the largest in a sample, covered in full adult pelage, molars obviously worn, occlusal surfaces retain pattern of major cusps, but their enamel margins are worn low, so the dentine is broadly exposed with some of the cusp rows coalesced at their labial and lingual margins, labial cusplets nearly obliterated); (3) young adult (body size usually smaller than older adults, covered in fresh adult fur, molars slightly worn, enamel borders of cusps much higher than the enclosed dentine with its restricted exposure, cusps and labial cusplets discrete, either not coalesced or only slightly so); (4) juvenile-adult (body size usually smaller than young adults, all molars erupted and slightly worn, clothed mostly in juvenile fur that conceals underlying replacement hairs of partially proliferated adult coat, older specimens retain juvenile pelage along back and rump but possess fresh adult fur on venter and sides of body); (5) juvenile (body size among smallest in a sample; covered in juvenile pelage that is easily recognizable compared to the adult coat, upper and lower third molars unerupted or if erupted usually unworn).

These roughly defined age groups are unequally represented among samples: old adults and juveniles are scarce, adults and young adults are most common. Old adults, adults, and young adults were combined into samples from which cranial and dental measurement values were obtained for multivariate analyses and univariate descriptive statistics. Recognition of relative age classes was important for identifying relative age of holotypes and subfossils as well as gauging the position of particular specimens showing incongruous distributions in principal-components and canonical-variate ordinations.

Males and females were not separated in any of the statistical analyses. Examined side by side, size differences in adult skulls of males and females within a single species collected from the same area appeared negligible. This observation was reinforced by results from determining significance of differences between means for cranial and dental variables of each sex (t-test) in samples of Bunomys chrysocomus (a member of the small-bodied B. chrysocomus group), B. penitus, and B. fratrorum (both belonging to the large-bodied B. fratrorum group), the only three species for which large samples were available (table 1). Within each of the species, differences between means were not significant across most variables—sex is a trivial contribution to intrasample nongeographic variation of cranial and dental variables.

TABLE 1

Differences in Means of Cranial and Dental Variables between Sexes in Samples of Bunomys chrysocomus, B. penitus, and B. fratrorum (Mean ± 1 SD are listed; samples consist of young to old adults. Probability values [P] are derived from t-tests; significant P values [≤ 0.05] are in boldface.)

Results of principal-components analysis of the three species (not illustrated here) did not reveal a different pattern in morphometric variation among the cranial and dental variables due to sex. The distribution of specimen scores projected onto first and second components for each species produced a single cloud of thoroughly intermixed points for males and females—polygons enclosing maximum dispersion of scores representing each sex, and ellipses outlining 95% confidence limits for cluster centroids broadly overlapped.

Weak sexual dimorphism in cranial and dental variables generally characterizes nongeographic sexual variation among muroid rodents. For examples of sigmodontines, see Carleton and Musser (1989, 1995 [Microryzomys and Oligoryzomys], Carleton et al. (1999 [Sigmodon]; 2009 [Oecomys]), Myers and Carleton (1981 [Oligoryzomys]), Voss (1991 [Zygodontomys]), Emmons and Patton (2012 [Juscelinomys]), and Percequillo et al. (2011 [Drymoreomys]); for murine examples, see Carleton and Robbins (1985 [Hybomys]), Carleton and Martinez (1991 [Dasymys]) Carleton and Van der Straeten (1997 [Lemniscomys]), Carleton and Byrne (2006 [Otomys]), Carleton and Stanley (2005, 2012 [Hylomyscus and Praomys]), Helgen and Helgen (2009 [Pseudohydromys]), Musser (unpublished data [Margaretamys, Rattus facetus, and Coccymys]), Musser and Durden (2014 [Echiothrix]), Van der Straeten and Verheyen (1982 [Hybomys]), Heaney et al. (2006 [Apomys, Batomys, and Limnomys]), and Balete et al. (2012 [Soricomys and Archboldomys]). The sigmodontine Oryzomys couesi is a noteable exception (Carleton and Arroyo-Cabrales, 2009).

Statistical Analyses

Standard univariate descriptive statistics (mean, standard deviation, and observed range) were calculated for population samples (identified in table 2) and for species and are listed in tables scattered through the text.

TABLE 2

Population Samples Employed in Univariate and Multivariate Analyses of Cranial and Dental Variables for Species of Bunomys Localities, along with elevations and geographic coordinates, are referenced in the gazetteers and marked on the distribution maps. Brackets enclose total number of specimens for each species. Specimens measured are identified in footnotes.

TABLE 2

(Continued)

Principal-component and discriminant-function analyses were computed using original cranial and dental measurements transformed to natural logarithms. Principal components were extracted from a variance-covariance matrix, and canonical variates were extracted from the discriminant-function analyses; loadings (correlations) of the variables are given as Pearson product-moment correlation coefficients between the extracted principal components or canonical variates and the log-transformed input variables. Probability levels denoting the significance of the correlations in both kinds of analyses are unadjusted. Individual specimen scores were projected onto scatter plots usually bounded by two axes representing the first two factors extracted. Most analyses are based on 16 cranial and two dental measurements from intact skulls of adults (young to old); some scatter plots were generated using fewer variables because only damaged skulls or subfossil fragments were available for analysis; a few comparisons utilized lengths of head and body, tail, hind foot, and ear.

Plottings of cluster analyses (UPGMA) provide visual patterns that reflect similarity or contrast in the combination of cranial and dental dimensions among geographic samples of a single species or among samples of separate species. UPGMA clusters of population samples were derived from Mahalanobis distances (squared) among population sample centroids and produced by the unweighted pair-grouup method employing arithmetic averages.

The statistical packages in SYSTAT 11 for Windows, Version 11 (2005), were used for all analytical procedures.

Ratio Diagrams

Data used in constructing the ratio diagrams in figures 19, 56, 91, 93, and 95 were derived from values for mean, standard deviation, and sample size of variables listed in table 42. For each measurement, the absolute value of the mean, and plus or minus two standard errors of the mean, were converted to logarithms. Next, the logarithm of the mean of the standard was subtracted from the logarithms of the mean, and plus or minus two standard errors, of the comparative sample. Measurements larger than the standard are thus represented by positive values, those smaller by negative values. Straight or dashed lines connect sample means, and bracketing symbols represent ±2 SE of the mean. A sample having the same proportions as the standard are represented by mean values on a line parallel to that of the standard regardless of absolute size. Also, if values for the sample being compared with the standard are similar in absolute size, they will be close together on the diagram. If proportions between any of the measured dimensions are similar, the positions of their points relative to each other on the horizontal scale will be similar.

Anatomy

Terminology follows Brown (1971) and Brown and Yalden (1973) for particular external features of the head and limbs; Bugge (1970) for cephalic arteries; Carleton (1980), Musser and Newcomb (1983), Carleton and Musser (1984), Wahlert (1985), Musser and Heaney (1992), Voss (1988), and Carrasco and Wahlert (1999) for cranial foranima and cranial morphology. Names of cusps and cusplets of maxillary (upper) and mandibular (lower) molars are indicated in figure 11; sources for the terminology are explained in the legend.

Chromosomes

I prepared karyotypes in the field from chromosomes of cells in bone marrow tissue, and processed them by employing colchicine, hypotonic citrate, and flame drying, procedures that were outlined by Patton (1967). The slides were made and stained at my camps in the forests.

Four terms describe the shape of each chromosome relative to position of the centromere: metacentric (the chromosome is biarmed, one arm being about the same length as the other); submetacentric (one arm is shorter than the other, about a third of its length); subtelocentric (one arm is very short relative to the long arm on the other side of the centromere); and acrocentric (the centromere is at the tip of the chromosome or near enough that any portion on the other side of the centromere is so short as to be indistinguishable or nearly so).

The fundamental numbers listed in table 12 and text are broken into the number of autosomal arms (FNa) and the total number of arms (FNt, including XX for females and XY for males). Jim Patton (in litt., 2013) suggested using these two categories and his reasoning stems “from the independent evolutionary trajectories typically operating on autosomes and sex chromosomes—the combination of 2N + FNa and/or FNt thus provides quick insight into mechanisms that might underlie evolutionary change.”

Stomach Contents

I recorded in my field journals the contents found in stomachs of some freshly caught rats. Sometimes only a general description was possible—presence of fruit, seeds, fungi, and arthropods, for example—but often freshly ingested and masticated fruit, seeds, and fungi could be easily identified to at least genus by color, shape, and texture; oligochaete earthworm pieces were obvious; and some arthropod remains could be identified to order. Many samples were preserved in ethanol, which I examined later in the laboratory under a dissecting microscope, and found additional arthropod particulates—termites especially—not seen in the field. I supplemented this material by extracting stomachs from undissected rats. Stomachs were removed by severing the posterior end of the esophagus and the anterior section of the duodenum. I bisected the isolated stomach along the midfrontal plane, transferred the contents to a white ceramic dish, and examined them with a dissecting microscope. In addition to remains of ingested foods, stomachs contained strands of hair, likely ingested during grooming. Stomachs emptied in the field are still attached to the gasterointestinal tract of carcasses preserved in fluid at AMNH. Those stomachs extracted in the laboratory are stored, with their contents, in leakproof vials in the fluid collection at AMNH.

My survey of stomach contents is not exhaustive. I did not extract the stomach of every specimen collected, and did not attempt to identify every tiny arthropod fragment. Chewed pieces of fungi were easily recognized and I was able to locate in the forest some of the fungal species; I relied on gross evidence for fungal remains, without surveying stomach contents for spores or other microscopic remains.

Most species of Bunomys readily enter live traps, quickly adapt to a cage environment, and can be kept healthy for some time. I supplied captives with a range of forest foods to determine what would be accepted or rejected.

The problem of identifying arthropod remains, particularly insects, found in the stomachs of Bunomys was solved by tapping David Grimaldi's (AMNH) wide-ranging knowledge of insects in particular and arthropods in general. Several times he unselfishly diverted his own research efforts to examine vials containing a range of different insects and to provide me with identifications along with ecological insights relating to these invertebrates. I also consulted various general publications covering insects, but found Grimaldi and Engel's (2005) Evolution of the Insects to be the most rewarding not only for the information it contained in text and illustrations but for the intellectual satisfaction derived from learning about different insect groups of interest to me and their evolutionary origins.

Geography (fig. 1)

Fig. 1.

The island of Sulawesi showing its four peninsulas and core or central region. Highlighted are four mountainous regions that support suites of endemic mammals discussed here. Boundaries separating other relevant areas of endemism are indicated by dashed lines: SM-D  =  lowland reaches of the Sungai Onggak Mongondaw and Sungai Onggak Dumoga; SB-DL  =  lowlands of the Sungai Bone and Danau Limboto; TD  =  Tempe Depression.

Fig. 2.

Skull of an adult Bunomys chrysocomus illustrating limits of cranial and dental measurements I employed. Definition details are provided in the text.

The island of Sulawesi consists of a central region from which four arms or peninsulas radiate: the northern peninsula, which ends in a northeastern jog; the eastern peninsula; the southeastern peninsula; and the southwestern peninsula. I use these informal labels when describing distributions of the species of Bunomys over the island, and refer to the cenral portion as Sulawesi's core, or simply “core.”

In figure 1 and the text I refer to four mountainous regions that support suites of endemic mammals discussed here. The west-central highlands or west-central mountain block, which forms the western portion of Sulawesi's core. It is the region of foothills, peaks, and interior valleys situated above 100 m and lying roughly west of Danau Poso and extending from the Palu area in the north to Pegunungan Latimojong in the south. Pegunungan Mekongga is at the center of a less expansive highland region on the southeastern peninsula. Gunung Tambusisi is at the western end of the mountain chain forming the backbone of the eastern peninsula. The volcano Gunung Lompobatang forms the highest landscape on the southwestern peninsula. Other regional areas of endemicity relevant to distributions of the species in Bunomys are highlighted in figure 1 and discussed in the text.

Throughout the report I use the Indonesian terms sungai (stream or small river), kuala (stream discharging directly into the sea), gunung (mountain), pegunungan (mountain range), pulau (island), kepulauan (archipelago), selat (strait), tanjung (cape), and teluk (bay).

Bunomys and My Collecting Areas

During 1973–1976, I lived and worked in the forests of central Sulawesi focusing on an inventory of murid rodents, of which a significant portion consisted of samples containing four species of Bunomys. I worked in two regions (fig. 3). One included low-to-middle elevations along tributaries of the Sungai Miu and to the east in the drainage basin of Danau Lindu; and higher elevations from Gunung Kanino, a ridge descending from Gunung Nokilalaki, all the way to the summit of the latter (fig. 4); this comprised a transect extending from 290 m where the small Sungai Oha Kecil joins the Sungai Miu to the summit of Gunung Nokilalaki at 2280 m (which in this review I refer to as my transect) and included habitats in lowland tropical evergreen rain forests and montane forests in the northern portion of the west-central mountain block. The other region was east of the west-central block in the lowlands of the Malakosa area in the northeastern portion of Sulawesi's core bordering Teluk Tomini (fig. 4) where the elevations covered ranged from near sea level at Kuala Navusu to ridges behind Sungai Tolewonu at about 1000 m (fig. 5); lowland tropical evergreen rain forest covered the area. The Sungai Miu-Danau Lindu-Gunung Nokilalaki transect was intended to explore habitats in both lowland tropical evergreen and montane rainforest formations. Work in the Malakosa region concentrated on surveying lowland habitats, particularly at elevations below 290 m.

Fig. 3.

The northern portion of Sulawesi's core showing the two regions where I worked: the Sungai Miu–Danau Lindu (left dashed square) and Malakosa (right dashed square) areas. Three of H.C. Raven's collection sites are also indicated on the map: Gunung Lehio, southwest of Kulawi; Pinedapa, west of Mapane; and Rano Rano, in the mountains west of Pinedapa. Enlargements of the Danau Lindu and Malakosa areas are shown in figures 4 and 5, respectively.

Fig. 4.

The Sungai Miu–Danau Lindu area in the west-central mountain block. Where the Sungai Oha Kecil flows into the Sungai Miu at 290 m was my lowest camp, the summit of Gunung Nokilalaki the highest place I worked. Tropical lowland evergreen rain forest embraces the area from the Sungai Oha Kecil to the camp along the Sungai Tokararu at 1150 m. The camp at 1440 m was on a ridge, part of Gunung Kanino, in lower montane rain forest. The lower camp at 1150 m (Sungai Tokararu) was at the western end and base of the Kanino highland. The highest camp at 1700 m was situated on the flanks of Gunung Nokilalaki, which at altitudes above about 2000 m was covered with upper montane rain forest. Ambient air temperatures, relative humidities, and rainfall recorded at the camps are provided in table 3.

Fig. 5.

The region south of Malakosa in Sulawesi's northeastern core. My two lowland camps in tropical lowland evergreen rain forest are indicated. The area lies east of the west-central mountain block. See table 3 where ambient air temperatures, relative humidities, and rainfall recorded at the two camps are summarized.

Ambient air temperatures, relative humidity, and rainfall patterns recorded at the camps and other elevations are summarized in table 3.

TABLE 3

Ambient Air Temperature, Relative Humidity, and Rainfall Pattern at Camps in Central Sulawesi^a

All the kinds of data derived from inventories of small mammals obtained by trapping originate not only from the animal caught in the trap but also from the spot where the trap was placed: for example, on the ground or at levels in the forest above the ground, in the open or beneath cover, on hillsides or ridgetops, on stream terraces or decaying tree or palm trunks and limbs bridging streams, in primary forest or disturbed forest at various stages of reforestation. I needed to know where each animal was trapped, so during my first year I set my own traplines, ran them myself, and recorded the habitat at the spot where each small mammal had been taken. During the second and third years I was aided by two excellent helpers, Aminudi and Usma, both from a village near Sadaunta in the drainage of the Sungai Miu. At each of the camps, the three of us set three different traplines, each consisting of 100–150 traps, and each of us would check his own line. When Aminudi and Usma first set their lines, I accompanied them so I would know the location of their traps and could record habitat and elevation at any site of capture. None of our specimens came from local trappers.

We used a variety of traps: cage live traps fabricated in Taiwan, Sherman live traps (both 6 inch and 10 inch models), Victor rat snap traps, the smaller Museum Special snap traps, and Conibear body-gripping traps (single spring #110). Bait consisted of a combination of peanut butter, rolled oats, raisins, and bacon ground to a firm paste.

We concentrated our trapping efforts in old-growth (primary) forest. For the most part we avoided second-growth and anthropogenic habitats associated with village houses and gardens, rice fields, and other kinds of croplands. Exceptions were places in primary forest where a large tree had been removed for building materials; small areas of coffee groves situated in the primary forest where the canopy trees remained intact, but the understory had been partially cleared for coffee trees; and clearings deep in the primary forest caused by fallen canopy trees, landslips, and stream flooding due to nonanthropogenic causes.

I provide this brief description of the regions in which we worked and collected examples of Bunomys and the note on trapping protocol because along with acquiring material for taxonomic study, I also obtained habitat and other biological information that are attached to the specimens collected. These natural history data are summarized for four species of Bunomys, and constitute the only firsthand natural history information I had available for this review.

Gazetteers and Maps

Localities from which samples were collected, along with the institutional acronym and catalog number of each specimen examined, are listed in a gazetteer of collection localities for each species. No specimen is listed that I did not personally examine. Descriptions of locality and elevations (recorded in meters or feet, depending on the convention used by the collector) were taken from labels attached to skins. These basic data were enhanced where necessary by relevant information from field journals, other archival material, and published expeditionary accounts and gazetteers; sources are cited in the locality entry.

Spelling of locality names are those approved by the United States Board on Geographic Names in the Gazetteer of Indonesia (3rd ed.), volumes 1 and 2, published by the Defense Mapping Agency, Washington, D.C., in 1982 (referenced as USBGN Indonesia, 1982). Some localities could not be located in that gazetteer but were found on the topographic map sheets described below; other spellings come from my field notes.

Coordinates for some collection localities were found in USBGN Indonesia (1982) or the Gazetteer of Celebes published in 1944 through the Hydrographic Office of the United States Navy Department (HOUSND Celebes, 1944). Coordinates for most of Harry C. Raven's collection localities were estimated from his personal copy of a Dutch map of Celebes on which he had marked his camp sites and travel routes (Overzichtskaart van het eiland Celebes, Schaal 1∶1,250,000, “met aanduiding van de politieke indeeling, de organisatie van het bestuur, de bestaande en nog aan te leggen verkeerswegen en van de groote cultuur- en industrieele centra. Samengesteld op last van de N.I. Regeering” (“indicating the political divisions, the organization of the administration, the existing and the still to be built road system, and the large cultural and industrial centers. Created at the request of the N.I. [Nederlands Indië  =  Dutch East Indies] Government”), published in 1909), and referred to in the text as “Raven's map.” Coordinates for my collection localities, as well as height above sea level for places for which altitudes were not recorded by collectors, were estimated from “JOINT OPERATIONS GRAPHIC-GROUND” topographic maps, scale 1∶250,000, compiled by Mapping and Charting Establishment RE, 1969, and published by the Director of Military Survey, Ministry of Defence, United Kingdom, 1970, or by the Army Map Service, Washington, D.C. (Sheets NA 51-9 [1967], NA 51-12 [1967], NA 51-14 [1967], SA 50-8 [1971], SA 51-1 [1970], SA 51-5 [1967], and SA 51-14 [1967], SB 50-8 [1966], SB 51-1 [1970]). Coordinates for localities trapped by personnel associated with the Navy Medical Research Unit (NAMRU) stationed in Jakarta were obtained from their archival records.

Forests and Plants

The tropical rain forests embracing the habitats of Sulawesi's species of Bunomys will be described broadly in the accounts of species by applying three of the forest formations categorized by Whitmore (1984): tropical lowland evergreen rain forest, tropical lower montane rain forest, and tropical upper montane rain forest. Whitmore's descriptions of these different forest landscapes are illuminating and, as he notes, an extension and elaboration of P.W. Richards's (1952) classic “Tropical Rain Forest,” which readers will also find informative (a second edition was published in 1996).

We collected botanical samples at the various camps and had some examined by specialists who identified most of the material to either genus only or to genus and species. Because some of those scientific names are now synonyms or were found to be invalid, I checked the names against those compiled in The Plant List (2013), version 1.1 ( http://www.theplantlist.org/).

Type Species

Mus coelestis Thomas, 1896: 248.

Emended Diagnosis

A genus in Rattini (Lecompte et al., 2008; Aplin and Helgen, 2010) or Rattus Division (Musser and Carleton, 2005) of Murinae within Muridae (as delimited by Musser and Carleton, 2005) that is distinguished from all other described murine genera by the following combination of traits: (1) all species terrestrial in habitus; (2) dorsal pelage covering head and body dense and soft, with guard hairs only slightly longer than overhairs, so coat has an even surface, dorsal coat dark gray, dark blue-gray, brownish gray or brown speckled with buff and black; (3) ventral coat soft and dense, whitish gray, dark grayish white, blue-gray lightly speckled with white, grayish pale buff to ochraceous gray, demarcation between upperparts and underparts inconspicuous; (4) muzzle elongate in most species, ears rubbery in texture, gray to brown; (5) tail shorter than combined length of head and body, coequal or slightly longer (mean values of LT/LHB range from 79% to 102%), scales small, their annuli overlapping, three short hairs associated with each scale, dorsal surface grayish bown to brown, ventral surface ranges from white (tail is bicolored) to brown (tail is monocolored), a white tip occurs infrequently or is usual, depending upon the species; (6) digits white, dorsal surfaces of carpal and metacarpal regions white to brown, palmar surface adorned with usual number of tubercles found in murines (three interdigitals, a thenar, and a hypothenar), hind foot elongate with full complement of plantar tubercles (four interdigitals, a thenar, and a hypothenar), front claws elongate in three species; (7) two pairs of inguinal teats; (8) testes of adults large relative to length of head and body (22%) or smaller (8%–15%); (9) rostrum of adults elongate and either narrow or broad, interorbital and postorbital margins bounded by low ridges, zygomatic arches flare from sides of skull, posterior zygomatic root situated low on braincase, braincase boxlike (moderately wide and deep), occiput deep, no cranial flexion; (10) zygomatic plate wide or narrow, its anterior margin either barely projecting beyond dorsal maxillary root of zygomatic arch or bowed beyond it, its posterior edge even with the anterior third of the first molar; (11) squamosal intact (not perforated by a subsquamosal foramen); (12) alisphenoid struts absent; (13) incisive foramina long in most species and moderately wide, their posterior margins ending well anterior to front faces of first molars; (14) molar rows diverge slightly posteriorly, bony palate short with its posterior margin even with back faces of third molars or extending slightly beyond them, palatal surface with moderately deep palatine grooves, posterior palatine foramina at level where second and third molar touch; (15) moderately long and narrow sphenopalatine vacuities; (16) wide pterygoid plates with moderately deep pterygoid fossa, small sphenopterygoid openings; (17) medium or large ectotympanic (auditory) bulla relative to skull size, capsule incompletely covering periotic, posterodorsal wall of carotid canal formed by periotic and not bullar capsule; (18) large stapedial foramen, no sphenofrontal foramen or squamosal-alisphenoid groove, indicating a carotid arterial pattern widespread within Murinae (char. state 2 of Carleton, 1980; pattern 2 described by Voss, 1988); (19) dentary somewhat elongate, low ramus between incisor and molar row, moderately high ascending ramus, large coronoid and condyloid processes, end of alveolar capsule forming modest labial swelling level with base of coronoid process; (20) upper and lower incisors with orange enamel and ungrooved anterior faces, uppers emerge from the rostrum at a right angle (orthodont) or curve slightly caudad (opisthodont), each lower incisor awl shaped with elongate wear facets; (21) each first upper (maxillary) molar with five roots, the second with four, and the third with three, each first lower (mandibular) molar with four, the second and third molars each with three; (22) molars brachydont, cusp rows forming simple cuspidate occlusal patterns, third molar small relative to others in toothrow; (23) first and second rows of cusps on first upper molars laminarlike or gently arcuate because cusp t3 on the first row and cusp t6 on the second row are oriented horizontally and broadly coalesced with the respective central cusp t2 and cusp t5, anterior row of second molar shaped like second row of first molar; (24) no cusp t7 or posterior cingulum on upper molars, and no other occlusal embellishments (such as an enamel ridge projecting from anterolingual surface of cusp t8 anteriorly to posterior margin of lingual cusp t4, a labial enamel ridge connecting anterolabial margin of cusp t9 with posterolabial margin of cusp t6, or a comparable but shorter ridge projecting from the anterior surface of cusp t5 to meet the posterior margin of cusp t3 near the cingulum, all typical of some other murines with more complicated enamel occlusal patterns; the New Guinea Coccymys is an example [Musser and Lunde, 2009]), cusp t3 typically missing from second molars in all but two species and from third molar in most specimens; (25) anteroconid formed of large anterolingual and anterolabial cusps, anterocentral cusp absent, anterolabial cusp present or missing from second and third lower molars depending upon the species, anterior labial cusplets typically not present on first and second lower molars, but posterior labial cusplet present on each tooth, posterior cingulum round or elliptical; (26) stomach unilocular-hemiglandular; (27) sperm head asymmetrical and falciform in shape, with single apical hook lacking ventral processes, spermatozoal tail short to moderately long; and (28) karyotype, 2N  =  42, FNa  =  56 or 58, FNt  =  58, 60, or 61.

Contents

Bunomys chrysocomus, B. coelestis, B. prolatus, B. torajae, n. sp., B. fratrorum, B. andrewsi, B. penitus, and B. karokophilus, n. sp.; all are endemic to Sulawesi.

Geographic and Elevational Distributions

One species is spread over the island, the others restricted to certain regions (table 5; also see the maps showing collection localities in figs. 22, 50, and 51). Bunomys chrysocomus is the most widespread (as documented by voucher specimens): samples are from the central core and most of the peninsulas and were collected through an elevational range bracketed by lowland to montane habitats. Bunomys coelestis is known only from montane forest on Gunung Lompobatang, the highest landform in the southwestern peninsula; the montane B. prolatus has been taken to date only from Gunung Tambusisi at the western terminus of the eastern peninsula; and B. torajae, n. sp., has been collected so far only from montane habitat on Gunung Gandangdewata in the southern section of the west-central mountain block. Bunomys fratrorum is endemic to the northern peninsula east of the Gorontalo area where it occupies tropical lowland evergreen and montane rainforest habitats. Bunomys andrewsi occurs primarily in tropical lowland evergreen rain forests and is represented by voucher material from the Sulawesi's core, the western end of the eastern peninsula, and the southeastern and southwestern peninsulas. Bunomys penitus is strictly montane, found so far only in the west-central mountain block and in Pegunungan Mekongga on the southeastern peninsula. The only samples of B. karokophilus, n. sp., come from tropical lowland evergreen rain forest at middle elevations in the northern portion of the west-central region.

TABLE 5

Summary of Elevational Distributions (m) over Mainland Sulawesi for Species of Bunomys derived from Voucher Specimens See the maps showing collection localities in figures 22, 50, and 51.

Cooccurrence among the Species

The patterns of sympatric or parapatric geographic distributions as well as syntopic occurrences among the species of Bunomys is summarized in table 6 and elaborated in the accounts of species.

TABLE 6

Summary of Sympatry over the Mainland of Sulawesi for Species of Bunomys derived from Voucher Specimens

Description

Morphological variation categorizing the species of Bunomys reflects rats of medium body size (fig. 6; table 7) adapted to terrestrial habitats. The general character variation as expressed in live animals and preserved specimens is described below under external form (fur, ears, tail, feet, teats, and testes), gross spermatozoal morphology, gross stomach structure, skull, and teeth. Each species is characterized by its own combination of traits and these will be addressed in the accounts of species.

Fig. 6.

Four species of Sulawesian Bunomys drawn from photographs of live animals: B. andrewsi (upper left), B. penitus (upper right), B. chrysocomus (lower left), and B. karokophilus, n. sp. (lower right). All occur in forests somewhere along my transect extending from the lowlands at Sungai Oha Kecil to the summit of Gunung Nokilalaki; only B. andrewsi was found in the Malakosa area.

TABLE 7

Contrasts in Physical Size among Species of Bunomys Listed are ranges for lengths of head and body (LHB), tail (LT), hind foot (LHF), ear (LE), skull (ONL) and maxillary molar row (CLM1–3) in millimeters; LT/LHB (%); and weight (WT) in grams. Data are summarized from univariate descriptive statistics presented in tables scattered throughout the text.

Chromosomes

Metaphase chromosomal spreads are available from Bunomys chrysocomus, B. andrewsi, B. penitus, and B. karokophilus, n. sp. (table 12); no karyotypes have been published for B. coelestis, B. prolatus, B. torajae, n. sp., or B. fratrorum.

TABLE 12

Summary of Karyotypic Data for Samples from Four Species of Bunomys^a See figures 13–Fig. 14.15.

Bunomys chrysocomus (N  =  33) and B. andrewsi (N  =  5) express the same chromosomal complement: 2N  =  42, FNa  =  56, FNt  =  58 (fig. 13). The autosomal set consists of one pair of large subtelocentrics, 11 pairs of acrocentrics that range from a large first pair to succeeding pairs of smaller chromosomes in a graded series, and seven pairs of small metacentrics. The presumed X chromosome of the males (the largest chromosome of the heteromorphic pair) is biarmed and the small Y chromosome is acrocentric. Each female has a pair of large acrocentrics, which I assume to be the X chromosomes; the remaining chromosomes in the karyotype are similar to those of the males, both in number of kinds and gradations in size.

Fig. 13.

Karyotypes from a female (upper set; AMNH 223077) and a male (lower set; AMNH 223292) Bunomys chrysocomus: 2N  =  42; FNa  =  56, FNt  = 58. The gross chromosomal complement of B. andrewsi (not illustrated) is similar to this karyotype. Additional information is provided in table 12 and the text.

Bunomys penitus (N  =  9) has a diploid number of 42, an FNa of 58 for both sexes, FNt of 60 for females and 61 for males (fig. 14). The autosomal set consists of two pairs of large subtelocentrics (only one pair in B. chrysocomus and B. andrewsi), 11 pairs of acrocentrics, and seven pairs of small metacentrics. As in B. chrysocomus, the presumed X chromosome of the males (the largest chromosome of the heteromorphic pair) and the small Y chromosome are acrocentrics. Each female has a pair of large acrocentrics, which I have identified as the X chromosomes; the remaining chromosomes in the karyotype are similar to those of the males.

Fig. 14.

Karyotypes from a female (upper set: AMNH 223927) and a male (lower set; AMNH 223924) Bunomys penitus: 2N  =  42; FNa  =  58 for both sexes, FNt  =  60 for the female and 61 for the male. Two large subtelocentric pairs are present instead of one, which is the typical number in the karyotypes of B. chrysocomus and B. andrewsi (fig. 13). Additional information is provided in table 12 and the text.

The single male karyotyped of the new species, B. karokophilus, has a diploid number of 42, an autosomal fundamental number of 56, and total fundamental number of 60 (fig. 15). The autosomal set resembles that of B. penitus, except it has one additional acrocentric and one less metacentric. Unlike B. chrysocomus, B. andrewsi, and B. penitus, the presumed X chromosome of the male B. karokophilus, n. sp. (the largest chromosome of the heteromorphic pair), and the small Y chromosome are submetacentrics. I do not have the karyotype of a female.

Fig. 15.

Karyotype from a male (AMNH 225041) Bunomys karokophilus, n. sp.: 2N  =  42; FNa  =  56, FNt  =  60. The presumptive sex chromosomes are submetacentrics, which contrasts with the acrocentrics characterizing the other three species, and six pairs of metacentrics are present instead of seven (figs. 13, 14). Additional information is provided in table 12 and the text.

Natural History

Based on my trapping experience, B. chrysocomus, B. andrewsi, B. penitus, and B. karokophilus, n. sp., are terrestrial and nocturnal. There is nothing in the morphology of B. coelestis, B. fratrorum, B. prolatus, and B. torajae, examples of which I have not collected, to indicate that these species are not also terrestrial and active during the night rather than during the day. Like other murines endemic to Sulawesi, the species of Bunomys live in forests. Most of my samples were collected from habitats in primary forest formations but a few were obtained in second-growth forest and coffee groves shaded by old-growth canopy and emergent trees; a few were collected near villages. Judged by recent samples obtained by other collectors, Bunomys andrewsi is common in second-growth forests. The species I encountered were usually encountered in wet and shaded habitats in tropical lowland evergreen rainforest formations and nearly everywhere in montane forest where the habitats remain cool and wet for most of the year. One species, B. karokophilus, n. sp., may be restricted to wet and shaded streamside sites.

Composition of diets is available for five of the eight species. Fruit, invertebrates, and small vertebrates comprise the diet of B. chrysocomus, B. fratrorum, and B. andrewsi, but B. chrysocomus and B. andrewsi are especially fond of invertebrates (insects, arachnids, centipedes, snails, and oligochaete earthworms). Bunomys penitus also consumes fruit and invertebrates as well as a variety of different fungi in its diet. Bunomys karokophilus, n. sp., is a fungal specialist, and its primary dietary component is the ear fungus Auricularia delicata. Diets of B. coelestis, B. prolatus, and B. torajae have yet to be documented. A summary of the different foods consumed, derived from examining contents of stomachs and survey of food accepted or rejected by captive rats, is presented in table 13. Details are provided in the individual accounts of species.

One or two young in litters are usual for those species for which this information is available—B. chrysocomus, B. andrewsi, B. penitus, and B. karokophilus, n. sp.

Ectoparasites, Pseudoscorpions, and Endoparasites

Sucking lice (Hoplopleura), fleas (Leptopsyllidae, Pygiopsyllidae, and Ceratophyllidae), ticks (Ixodidae), chiggers (Trombiculidae), and mites (Laelapidae) have been recorded as parasitizing seven of the eight species of Bunomys (no records from B. torajae). The combination of ectoparasites associated with the different hosts is summarized in table 14. Noted also in that table are pseudoscorpions (Chernetidae) found in the fur of Bunomys. “Pseudoscorpions in rodent fur are commensals that prey on ectoparasitic mites, lice and fleas. Also, large numbers of tiny phoretic (non-feeding) deutonymphal stages of histiostomatid mites [phoretomorphs] have been recorded attached to the posterior body (idiosoma) of many of the large laelapid mites removed from Sulawesi rodents (Whitaker and Durden 1987). “Combined, the ectoparasites, pseudoscorpions, and phoretomorphs can be called epifauna or epifaunistic arthropods” (L. Durden, in litt., 2013; see also Muchmore, 1972: 431; Eric Rickart kindly reminded me that pseudoscorpions are predators and not ectoparasites).

Table 14 also references the few endoparasites recovered from specimens of Bunomys: human blood fluke, liver fluke, and nematodes.

Details and published sources of the ectoparasite and endoparasite records as well as those of the pseudoscorpions are provided in the account of each species.

Synonyms

Frateromys (Sody, 1941), with Mus fratrorum as the type species, is the only generic synonym. More than one scientific name attaches to samples of Bunomys chrysocomus, B. andrewsi, and B. penitus, and reasons for their specific allocations are documented in the appropriate accounts of these three species. Bunomys coelestis, B. prolatus, and B. fratrorum have never been encumbered with synonyms; B. karokophilus, n. sp., and B. torajae, n. sp., are virginal.

Subfossils

Fragments of Bunomys chrysocomus and B. andrewsi excavated from cave deposits at the southern end of the southwestern peninsula constitute the only subfossils I have personally studied that can be attributed to Bunomys; all are from Holocene deposits. Some samples come from Ulu Leang I, a cave in the Maros region on the coastal plain of the southwestern peninsula where the sediments were dated as between about 9500 and 3500 b.p. Others are from a shallow deposit forming the floor of Batu Edjaja II, a small rock shelter (also at the tip of the southwestern peninsula) where age of the sediments range from about 4300 b.p. to modern (Bulbeck, 2004). The pieces in both samples are partially fossilized, that is, the organic materials have not been completely replaced by inorganic minerals, and I refer to them as subfossils. The descriptions of these fragments and data supporting their identifications are provided in the appropriate accounts of species.

Additional mammalian samples of subfossils collected on the southwestern peninsula exist and may contain examples of Bunomys. Ian Glover, who gave me the material referred to above, had earlier excavated more than 1000 mammalian cranial and postcranial fragments from Ulu Leang I and turned them over to the late A.T. Clason who tabulated 65 pieces representing murid rodents (Clason, 1976: 66) but did not identify them beyond family category—I have not seen the material.

Subfossil Bunomys have been collected from a cave (Gua Mo O'Hono) on the southeastern peninsula in the northern lowlands of the southeastern peninsula, north of the lakes district (Danau Matana, Mahalona, and Towuti). I have been helping Philip Piper and Sue O'Connor identify the excavated murid remains and those determinations will eventually be published elsewhere; Philip generously allowed me to list the species identified so far in table 81.

Holotype

SNSD B 612, the skin and skull of an adult male (original numbers are 1707 for the skin and 1727 for the skull) obtained by F. von Faber in 1876. External, cranial, and dental measurements, along with other data, are listed in table 18.

Until the advent of World War II, the holotype was in the collection at the Staatliches Naturhistorische Sammlungen Dresden, Museum für Tierkunde. It was apparently lost or misplaced for some time after the War (see Musser, 1970: 14), but fortunately has been found (Feiler, 1999: 409) and was loaned to me by A. Feiler, the retired curator of the mammal collection at Dresden.

The stuffed skin is intact (fig. 23), but parts of the pelage are discolored. The dorsal coat is dark brownish gray and has a slight rusty sheen due to color alteration: bands of the overhairs that are normally brown in recently collected specimens have altered to rust or yellowish brown. The appendages are dark brown, which is unusual, and are likely discolored. The dark brown ears are bent and fragile. The ventral coat is brownish buff and its color is not sharply demarcated from that of the upperparts. Except for the slight chromatic alteration of the dorsal coat and appendages, pelage color of the holotype falls within the range of variation present in the large series of B. chrysocomus I collected during the 1970s in the forests around Sadaunta, Danau Lindu, and Gunung Kanino (localities 7–33 in the gazetteer). Compared with a series of B. chrysocomus collected by C.H.S. Watts during the 1980s in the northeastern peninsula (localities 3 and 4 in the gazetteer), the holotype has a paler dorsal coat with rusty highlights (dark brownish gray with scatter of buff through the coat in the fresher specimens) and a duller ventral coat that appears soiled (contrasted to bright, buffy brown venters).

Fig. 23.

Holotype of Mus chrysocomus, an adult male (SNSD 1707  =  SNSD B 612). Measurements are listed in table 18.

The skull is incomplete (fig. 24). Most of the left zygomatic arch, the entire occipital region, and pieces from the roof of the mesopterygoid region are missing, and the basioccipital is cracked. The mandible is intact, as are the upper and lower incisors and maxillary and mandibular molar rows (fig. 25).

Fig. 24.

Holotype of Mus chrysocomus, an adult male (SNSD 1717  =  SNSD B 612). Upper set: Reproductions of the drawings published in Hoffmann's (1887) original description. Lower set: Photographic images of the actual skull. Measurements are listed in table 18.

Fig. 25.

Occlusal views of right maxillary (left image) and mandibular (right image) molar rows of the holotype of Mus chrysocomus (SNSD 1727  =  SMT 612). See table 18 for measurements.

Type Locality

Amurang (01°11′N, 124°35′E), locality 1 in the gazetteer and on the map in figure 22, the northeastern arm of Sulawesi, Propinsi Sulawesi Utara, Indonesia. Hoffmann (1887: 17) indicated the region of “Minahassa, Nord Celébes” to be the origin of the holotype and that is notated on the original skin tags. Feiler (1999: 409; and in a letter to me [quoted in Musser, 1970: 15]) narrowed the locality to Amurang, a town on the coastal plain near sea level. Minahassa is an expansive administrative region within the province of Sulawesi Utara (northern Sulawesi) between 0.8°–1.8°N and 124.3°–125.3°E on the northeastern peninsula of the island (coordinates are from Fooden, 1969: 134; also see the map in Whitten et al., 1987: xiv). Amurang is unlikely the actual collection site of the holotype because no other specimens to which reliable elevational data are attached have been encountered in coastal plain habitats (see below). F. von Faber, who presented the holotype to the Dresden Museum, stayed at Amurang during 1876 while he collected birds in the broader Minahassa region (Meyer and Wiglesworth, 1898: 7). The holotype was probably obtained beyond the coastal plain at a higher elevation somewhere in “Minahassa.”

Emended Diagnosis

Among the smallest in physical size (LHB  =  97–180 mm, WT  =  55–175 g, ONL  =  35.8–41.1 mm) of the Sulawesian species in Bunomys and further characterized by the following combination of traits: (1) a long muzzle, small eyes, and long external pinnae; (2) dark brown to brownish gray upperparts speckled with buff, grayish white underparts with some individuals washed with buffy, ochraceous, or rusty hues, dorsal surfaces of feet range from grayish white to brownish gray; (3) front claws moderetly long and robust; (4) tail averages shorter than length of head and body (85%–98%), brown or grayish brown on the dorsal surface, white, mottled brown, or brown along the ventral surface (5) white tail tip infrequent (20% of 396 specimens in 13 samples) and when present is short relative to tail length (mean  =  5.5%, range  =  1%–25%); (6) testes large relative to body size (22%); (7) sperm head long, thin, asymmetrical and falciform in outline, tail long; (8) skull gracile with a moderately long and narrow rostrum, wide upright or backward sloping zygomatic plate, bony palate projecting slightly beyond posterior margins of third molars, and large ectotympanic bulla relative to skull size; (9) molars small relative to size of skull and mandible; (10) cusp t3 occurs infrequently on second upper molar (17%) and third upper molar (5%); (11) anterior labial cusplets on first lower molar present in about half of sample, posterior labial cusplets typically present on first and second lower molars; (12) anterolabial cusp present on second lower molar in 90% of sample and on third lower molar in 65% of sample; and (13) karyotype, 2N  =  42, FNa  =  56, FNt  =  58.

Geographic and Elevational Distributions

Collection localities appear as a spotty pattern compared to Sulawesi's land area (fig. 22), but the scatter suggests B. chrysocomus to range throughout much of the island wherever lowland and montane evergreen rainforest formations persist. All samples of B. chrysocomus describe an altitudinal range from 250 m (in the Bogani Nani Wartabone National Park on the northern arm) to 2200 m (on Pegunungan Latimojong at the southern margin of the west-central mountain block). Modern specimens with reliable provenence data have not been collected in habitats below 250 m, strongly suggesting B. chrysocomus to be a denizen of forested hills, mountains, and intermontane valleys. The only sample from a coastal plain (0–100 m) consists of subfossil fragments from a cave on the southwestern peninsula; whether the specimens were obtained by mammalian or avian predators near the cave or at higher elevations is unknown.

The species is either uncommon or infrequently encountered by collectors in the northern peninsula and the few records from there are in the zone of tropical lowland evergreen rain forest. Besides the holotype, obtained somewhere in the Minahassa Region, three individuals come from Langgon at 700–800 m (locality 2 in the gazetteer and map in fig. 22) and 10 were taken at 250 and 300 m in the Bogani Nani Wartabone National Park (localities 3 and 4), where it appears to be relatively abundant. The northeastern peninsula of Sulawesi has been a focus for collecting mammals and birds since the 1800s, and why B. chrysocomus is not represented in museum collections by large samples from more localities is inexplicable.

H.C. Raven, who collected birds and mammals for the Smithsonian Institution, was one of the more successful of the early mammal trappers to have worked in the northeastern arm of Sulawesi, and his results are illustrative. He arrived in Menado in January of 1916 and remained in the northeast until the end of August with the intention of beginning his survey at the extreme end of the peninsula and working west toward Gorontalo (Miller, 1917: 29). Raven collected in primary forest habitats in lowlands and mountains where he garnered large samples of B. fratrorum (see gazetteer for that species) along with other species of murines, but never encountered B. chrysocomus. After August, he moved south to where the northern peninsula joins the central body of the island, planning to use either Palu or Parigi as a base and working north from there until he had surveyed all of the northern peninsula. His stations were scattered from west of Gorontalo in the north to the base of the peninsula in the south, and it is only there, at Bumbarujaba (locality 5), that he came upon B. chrysocomus.

Except for a specimen from the Mamasa area, seven specimens from Pegunungan Latimojong, and four individuals obtained on Gunung Balease, all three places in Sulawesi's west-central mountain block, most of the material I have studied came from highlands south of the Palu Valley in the northern part of the west-central region. Small samples are from south of the Palu Valley at Bakubakulu (600 m) in the Puro Valley, Gunung Lehio (1880–2185 m), and Gimpu. The bulk of the material was collected on my transect extending from 320 m along the Sungai Oha Kecil to 1555 m on Gunung Kanino, which includes the range from tropical lowland evergreen rain forest to lower montane forest. Apart from these localities are vast stretches of forested hills, mountains, and valleys unsurveyed for small mammals, so the actual distribution of B. chrysocomus throughout the west-central region remains to be discovered.

Available samples of B. chrysocomus from the core of Sulawesi come only from the west-central region (see the map in fig. 22), which suggests to me that the range of the species does not extend into coastal lowland habitats and that its absence from mountains east of the west-central mountain block (generally between Danau Poso and the coast rimming Telok Tolo) may reflect the lack of adequate surveys for small nonvolant mammals there. East of Danau Poso lie mountainous terrain (Pegunungan Pompangeo, for example) that has yet to enjoy surveys for small mammals. There seems no reason why B. chrysocomus does not occur in these eastern highlands—providing, of course, that forest has not been removed—because the species has been taken on the slopes of Gunung Tambusisi to the northeast at the western margin of the eastern peninsula.

Trapping efforts bolster the hypothesis that B. chrysocomus is absent from very low elevations. Along my transect in the northern part of the west-central mountain block, I did not encounter the species below 320 m—only B. andrewsi was caught at lower elevations (see fig. 103 and the gazetteer for B. andrewsi and map in fig. 50). Nor did I collect B. chrysocomus in the northern part of the eastern portion of the central core at Kuala Navusu and Sungai Tolewonu, lowlands and ridges just back of the northeastern coast (see the map in fig. 5). I trapped only B. andrewsi at Kuala Navusu (31–122 m), but did not encounter either species of Bunomys at Sungai Tolewonu (136–366 m). Farther south in the eastern coastal lowlands, H.C. Raven collected a large sample of B. andrewsi from the forest by Pinedapa at 31 m but no B. chrysocomus.

The eastern peninsula of Sulawesi is another region receiving little exploration for small mammals, and the range of B. chrysocomus throughout that area is unknown. My only sample comes from 1372–1829 m on the flanks of Gunung Tambusisi, located at the southwestern margin of the peninsula. Mammal surveys in the eastern arm have been few, and sampling macaques has been the focus of most research trips. One exception is a collection of rodents and bats made by Luis Ruedas in 1998 from lowlands in the eastern Poso and Banggai districts of the peninsula, and another is a collection made by Jake Esselstyn and Anang Achmadi from Gunung Tompotika at the eastern end of the peninsula, neither of which contained examples of B. chrysocomus. What species occur at middle and high elevations along the mountainous backbone of the eastern peninsula has yet to be determined.

Tropical lowland evergreen rain forest to lower montane forest is the broad habitat range in which samples of B. chrysocomus have been obtained from the southeastern peninsular arm of the island. A specimen from Pulau Buton, the small sample from Lalolei at 300 m, and the material from Pegunungan Mekongga collected at 1500 and 2000 m embody the material I have included in this report, nearly all obtained by G. Heinrich in the 1930s. Additional specimens of B. chrysocomus from the Mekongga highlands are reported by Mortelliti et al. (2012).

Three subfossil fragments from cave deposits in the Maros region (below 100 m), about 40 km northeast of Ujung Pandang, provide the only record of B. chrysocomus from the southwestern peninsula (table 27). The species apparently lived in forest habitats at low and moderately high elevations because montane forests between 1800 and 2500 m on Gunung Lompobatang, south of the caves, support populations of B. coelestis, the mountain counterpart of B. chrysocomus in this region. Much of the lowlands in the southwestern peninsula are deforested and converted to agriculture (Whitten et al., 1987: 93, 102; Bernard and De Koninck, 1996: 3), but low forest cover still exists in limestone regions, especially in the Maros hills (personal obs.; Whitten et al., 1987), which are difficult to traverse and have never been surveyed for small mammals, and possibly B. chrysocomus still lives in those places.

Sympatry with Other Bunomys

Througout Sulawesi, B. chrysocomus is broadly sympatric with all the other species of Bunomys (tables 6, 20; also see gazetteers), but samples documenting its occurrence at the same locality and taken in the same trapline are few. Among the two other species in the B. chrysocomus group, B. prolatus and B chrysocomus have been collected on the slopes of Gunung Tambusisi. The eight known specimens of B. prolatus were trapped on a ridge at 1830 m in upper montane forest. One B. chrysocomus was taken “just below the same ridge, at about the same altitude (6000 ft) but a few meters downslope, and on the same day (March 9) as were four examples of B. prolatus. Six specimens of B. chrysocomus were collected at 4500 and 4700 ft during the same period, March 6–27, 1980” (Musser, 1991: 6). Samples of both species are small—whether the altitudinal ranges of each narrowly overlap or the two are truely altitudinally parapatric can only be determined by future elevational surveys on Gunung Tambusisi.

No modern samples of B. chrysocomus are available from the lower slopes of Gunung Lompobatang at the tip of the southwestern arm of Sulawesi. It is represented there only by subfossil fragments collected on the western coastal plain. Its original altitudinal distribution on the volcano and throughout the southwestern peninsula in general is unknown. Forests above 1800 m contain B. coelestis, the montane relative of B. chrysocomus.

On the northeastern peninsular arm of Sulawesi, B. chrysocomus and the larger-bodied B. fratrorum are recorded at two localities (see gazetteers). One is Rurukan, but the samples were obtained during different years and the actual collection sites are unknown. The second place is in the Bogani Nani Wartabone National Park, 1 km north of Gunung Mogogonipa at 250 m. There during August 2–8, 1985, C. Watts collected two B. chrysocomus and three B. fratrorum. Thus, in this northeastern arm the two species are regionally sympatric and apparently syntopic at one collection site.

Bunomys chrysocomus and B. andrewsi have been recorded from the same places in four regions of Sulawesi. Both species come from the PuroValley at Bakubakulu, 600 m, in the northern portion of the west-central mountain block, where on July 30, 1973, NAMRU-2 personnel trapped two B. chrysocomus and two B. andrewsi.

I collected the two species along a portion of my transect that extended from the Sungai Oha Kecil at 290 m to the Sungai Sadaunta at 675 m in the valley of the Sungai Miu. At 457 m on the Oha Kecil, both species were taken in the same trapline on the same days during August, 16 and 17, 1974; along the Sungai Sadaunta at 675 m, both species were collected in the same trapline on February 10 and 12, 1974 (at the latter locality an example of B. andrewsi [AMNH 224107] was trapped in a runway beneath a rotting tree trunk laying in shrubby understory of streamside forest; during the next night a B. chrysocomus [AMNH 224108] was trapped in the same spot). Bunomys andrewsi was rare in this overlap zone, but B. chrysocomus was relatively abundant (see the elevational distribution of specimens in fig. 103).

Bunomys chrysocomus and B. andrewsi are sympatric, but may not be syntopic, on Gunung Balease in the southeastern portion of the west-central mountain block (table 20). During 2010, four examples of B. chrysocomus were caught between 980 m and 1240 m, a range through the upper limit of tropical lowland evergreen rain forest and into lower montane rain forest, on October 25, 28, and 29, and Nov 1. Downslope between 830 m and 925 m, 18 specimens of B. andrewsi were trapped in tropical lowland evergreen rain forest during the period, October 18–29. No B. chrysocomus were encountered below 980 m and no B. andrewsi above 925 m (elevational data was kindly provided by J.L. Patton and K.C. Rowe).

Finally, B. chrysocomus and B. andrewsi are represented by subfossil fragments extracted from sediments at Ulu Leang I, a cave in the Maros region on the western coastal plain of the southwestern peninsula. The pieces may have been originally packaged in owl pellets or scat from the civet, Macrogalidia. If so, we know nothing of the ranges of these predators or habitats in which they hunted and cannot now determine whether the two species of Bunomys lived together on the coastal plain or came from different elevations.

Except for the few places of syntopy, the ranges of B. chrysocomus and B. andrewsi are generally mutually exclusive. Places yielding large samples of B. andrewsi—such as Pinedapa, Kuala Navusu, Gunung Balease, and the coastal plain west of Pegunungan Mekongga—are either devoid of B. chrysocomus, the species is rarely encountered, or its microhabitat in those places was never or inadequately sampled. The interplay of environmental factors related to elevation and competition for food (insects, oligochete earthworms, snails, and some fruit form the diet of both species, judged by my field observations and examination of stomach contents; see table 13) may partly explain the checkerboard pattern. Reliable altitudinal measurements indicate that modern samples of B. chrysocomus have yet to be encountered below 250 m. In more or less continuous intact forest, which characterized the landscape along my transect in the west-central region, I collected B. chrysocomus from 320 m at Sungai Oha Kecil to 1555 m on Gunung Kanino. Elsewhere in the central core of Sulawesi, the species occurs in montane forests up to 2200 m. With a few exceptions, most collection sites for B. andrewsi are below 600 m, and many between 30 and 300 m; 1000–1600 m seems to bracket the upper limit of its elevational range. In primary forest at Pinedapa, H.C. Raven collected 22 B. andrewsi during about a month, but no B. chrysocomus. At 30 m, that place is likely too low and the environmental conditions unsuitable for B. chrysocomus. West of Pinedapa, in the Malakosa region, I worked along the Kuala Navusu for three months and the nearby Sungai Tolewonu for another two months and caught B. andrewsi between 30 and 122 m in the Navusu area but no B. chrysocomus. Work in the Tolewonu drainage extended from 137 m to 366 m, but neither one of the species was encountered in forest seemingly no different than that covering the Navusu drainage basin.

TABLE 13

Summary of Foods Eaten by Species of Bunomys Determined by surveying contents of stomachs from preserved animals, and recording the foods accepted or rejected by captive rats.

TABLE 13

(Continued)

Description

Hoffman (1887: 17) joined chryso, from the Greek meaning “gold,” to the Latin coma, referring to “hair” of the head, to produce chrysocomus, the combination meaning “golden haired,” which emphasized, in Hoffmann's eyes, the “gold-yellow” luster highlighting the dark brown dorsal coat of the new rat presented to the Dresden Museum by F. von Faber. His description follows (translated by E. Brothers; the original German version is provided in appendix 1):

A compact body and moderately long head, relatively short tail, dark brown, lustrous fur, and medium body size (LHB  =  97–180 mm, LT  =  90–180 mm, LHF  =  31–40 mm, LE  =  17–28 mm, W  =  55–175 g, ONL  =  35.8–41.1 mm) describes Bunomys chrysocomus (see the rendition of B. chrysocomus presented in fig. 6), which among members of the B. chrysocomus group is physically similar to B. coelestis, but smaller than B. prolatus and B. torajae, n. sp. (tables 7, 19). The dorsal coat is dense, smooth, and soft to the touch; it is 12–15 mm long over the back on rats from lowlands, but reaches 20 mm on those from middle and high elevations. Dark brown with buffy speckling (produced by the combination of dark brown and buffy bands of the overhairs) describes the typical coloration of the dorsal coat covering most of the the head and body; sides of the body are paler, a grayish brown (because the brown and buffy bands are reduced in lengths or absent, more of the gray bases of the underhairs and overhairs dominate). A few individuals exhibit a darker coat, brownish black with only slight speckling. Because guard hairs and overhairs are about the same length, the surface of the coat is smooth, and the glistening guard hairs impart sheen to the fur. The rhinarium and sides of the muzzle are brown.

Fur covering the underparts of the head and body is also soft and dense, but shorter (8–10 mm long) than the dorsal fur, which is the usual pattern in murids. The contrast in color between upperparts and underparts is evident but not sharply marked. Grayish white (bases of the hairs are gray, tips are unpigmented), gray tinged with pale buff (tips of the hairs are pale buff), or dark gray washed or saturated with buff or ochraceous (hairs with long gray bands and short buffy or ochraceous tips) illustrate the predominant variation in color within the samples, although grayish white is most common; chestnut overlays the chin, neck, and chest in some specimens, pigmentation similar to that seen in many examples of B. andrewsi. In the west-central mountain block, deeply pigmented underparts (buffy gray or ochraceous-gray) predominate in samples from lower montane forest (Gunung Kanino and Gunung Balease) but are seen in only a few specimens from tropical lowland evergreen rain forest.

In life, the ears (external pinnae) feel and appear rubbery to me; they seem to be naked but are sparsely covered by short hairs. Their color is variable, ranging from shiny gray through dark gray, dark grayish brown, and grayish black to blackish gray. The stiff dried ears of stuffed museum skins lack the rubbery texture of the live animal and have dried to a dark brown.

Averaging shorter than the combined length of head and body (LT/LHB  =  85%–98%), the tail's dorsal surface is some shade of brown, the ventral surface ranges from white to brownish; a white tail tip is infrequent (20% of 396 specimens in 13 samples; table 8) and when present is short relative to tail length (mean  =  5.5%, range  =  1%–25%). The following color patterns (ignoring any white tip) are present in any large sample of B. chrysocomus: (1) mottled brown on the dorsal surface, white for the full length of the ventral surface (a rare bicolored variant); (2) dark brownish gray along the dorsal surface, white below but very lightly speckled—still appears sharply bicolor, dark above and whitish below; (3) dark grayish brown or dark brown on dorsal surface, white on ventral surface and moderately to densely speckled grayish brown—no clear demarcation between dorsal and ventral surfaces; (4) densely speckled grayish brown on dorsal surface, slightly less speckled on ventral surface—appears grayish brown all over; (5) dark brown above, slightly paler below—appears monocolored.

Carpal and metacarpal along with tarsal and metatarsal surfaces vary in color, ranging from grayish white (skin is unpigmented and covered with short gray and silvery hairs), through whitish brown (sparsely covered with brown hairs) to brownish white and then dark brown (denser cover of brown hairs). Digits of front and hind feet are typically unpigmented and sparsely covered with short silvery hairs; in some individuals, the bases of the digits are gray, in a few others the digits are white and sparsely covered with brown hairs. The moderately long front claws are not concealed by ungual tufts, but thin tufts of silvery hairs lay over the hind claws. Palmar and plantar surfaces are typically unpigmented except for near the heel and over the tubercles, which are gray; specimens from Gunung Balease have dark brown palmar and plantar regions, the darkest I have seen.

Females exhibit the number of teats usual for all Sulawesian species of Bunomys—four, arranged in two inguinal pairs. Males have large testes relative to body size, as measured by lengths (table 9) and weights (Breed and Taylor, 2000). Gross and ultrastructural spermatozoal descriptions are provided by Breed and Musser (1991) and Breed (2004).

Juveniles have a distinctly different pelage than that of adults. It is shorter, has a velvety texture, and is very dark compared with the brownish adults—brownish black with a flat tone (lacking the glossy sheen of the adult fur). Underparts are dark grayish white. Coloration of ears, feet, and tail ranges through the same patterns seen in any large series of adults.

The small gracile cranium and mandible of B. chrysocomus is depicted in figures 16 and 37–Fig. 38.39. Their conformation and internal structure epitomizes the description of the Bunomys skull provided in the introduction to the morphological characteristics of the genus. Noteworthy features of the cranium are its wide interorbit, deep and boxy braincase, moderately long and tapered rostrum, low postorbital ridging, sloping anterior edge of the zygomatic plate in most specimens, relatively short incisive foramina, short projection of the bony palate past posterior faces of the third molars, and relatively large bullar capsules. Each dentary is gracile and somewhat elongate, especially that slim portion of the ramus between incisor and first molar (diastema).

Molars are small relative to size of the cranium and mandible, and the occlusal patterns of cusps (figs. 12, 25) mirror the general patterns already described for the genus. I point out here only the frequencies of certain cusps and cusplets. Cusp t3 occurs on the second upper molar in only 17% of the sample, and on the third upper molar in only 5% of all specimens examined (table 10). About half of all specimens surveyed support an anterior labial cusplet on the first lower molar, and posterior labial cusplets are typically present on the first and second lower molars; an anterolabial cusp is present on the second lower molar in 90% of the sample and on the third lower molar in 65% of all specimens surveyed (table 11).

Karyotype

2N  =  42, FNa  =  56 and FNt  =  58, comprised of seven pairs of metacentric chromosomes, one pair of subtelocentrics, and 12 pairs of acrocentrics; the sex chromosomes are acrocentrics (fig. 13, table 12).

Comparisons

In its morphology, Bunomys chrysocomus most closely resembles the other members of the B. chrysocomus group—B. coelestis, B. prolatus, and B. torajae, n. sp.—and is compared with them in those three respective accounts. Bunomys chrysocomus is also contrasted with each of the species in the B. fratrorum group in the accounts of B. fratrorum, B. andrewsi, B. penitus, and B. karokophilus, n. sp.

Geographic Variation

Morphological variation among available samples is estimated primarily from characters of dry museum skins along with qualitative and morphometric traits of the skull and dentition. In traits related to general body size, relative lengths of hind feet and tail, as well as fur and skin pigmentation, adult examples of B. chrysocomus, to my eyes, look similar whatever the geographic provenance of the specimen. I did not detect any noteworthy variation among population samples in dimensions of head and body, tail, hind foot, and ear; in texture and coloration of fur; in color of feet and ears; or in pigmentation patterns on the tail. In any large sample (the 146 from Sungai Oha Kecil and Sungai Sadaunta, for example), the range in chromatic tones of body fur and the range of patterns formed by brown and unpigmented regions of the tail is greater than the range of variation in these features I saw among most other geographic samples.

Some specimens are darker than most others. The four adults from Gunung Balease and the rats from Gunung Kanino have darker dorsal and ventral coats, feet, and tails than is typical of the individuals comprising most samples.

My assessment of variation in color of the fur, skin, and pattern of the tail revealed by its dorsal and ventral pigmentation is not quantified and derives from simple observation of skins. Coloration of the distal portion of the tail is an exception and I quantified the frequencies of a white tip and its length in samples (table 8). The results did not reveal a pattern among the samples that bore significant concordance with their geographic origins.

Lengths of head and body, tail, hind foot, and ear are statistically summarized by sample but I did not treat the data in any rigorous comparative way for several reasons. Samples are uneven in composition of adult classes (young to old). Except for the material from my transect most samples are small (table 19). And there is always the problem of comparing measurements obtained by different collectors. Was length of head and body measured separately from length of tail? Was the tail measured on the dorsal side from the rump to the tip or ventrally from the anus to the tip? Did the collector include or omit claws in obtaining values for length of hind foot? Is length of pinna (if obtained; H.C. Raven, for example, did not measure the ear) measured from notch to crown or from base of the pinna to crown?

Morphometric variation in cranial and dental variables among the population samples does exist (tables 21, 22), detectable not so much by side-to-side comparison of skulls of comparable age classes, but by multivariate analyses, and I relied on those results to reveal possible patterns of variation in morphometric traits over Sulawesi's landscape. Intersample geographic variation is less apparent in the ordination of specimen scores for all population samples of B. chrysocomus projected on first and second principal components (fig. 26). Scores representing the two large samples from my transect (Sungai Oha Kecil + Sungai Sadaunta, Danau Lindu + Gunung Kanino) are diffused along the lengths of both axes, and that cloud also embraces nearly all scores representing the other eight population samples, including scores for the holotypes of nigellus, rallus, koka, and brevimolaris (fig. 26, upper graph) as well as chrysocomus itself (fig. 26, lower graph). The positive and high loadings for most variables on the first component, along with significant correlations among all of them (table 23), point to size as primarily responsible for the spread of scores along the first axis with covariation in overall size of skull (occipitonasal length and zygomatic breadth), interorbit, rostrum (length and breadth), zygomatic plate, and palatal region (length of diastema, breadth of incisive foramina, length and breadth of bony palate, postpalatal length, and breadth of mesopterygoid fossa) being the most influential (r  =  0.43–0.78 for upper graph). Covariation among other variables (size of the braincase, lengths of incisive foramina and ectotympanic bulla) exert moderate force in the dispersion of scores, and size of molars express the smallest loadings and the least pressure. After full eruption the molars do not increase in dimensions and the braincase reaches nearly full size early in ontogeny, so the dispersion of scores along the first axis partly signals variation in the facial skeleton due to different stages of postweaning growth within adults (young to old) as well as some variation associated with geographic origin of the samples.

Fig. 26.

Specimen scores representing 10 population samples of Bunomys chrysocomus projected onto first and second principal components extracted from principal-components analysis of 16 cranial and two dental log-transformed variables. Upper graph: All variables are represented and scores for four of the five holotypes associated with B. chrysocomus are present. Lower graph: The holotype of chrysocomus is added; because the skull is incomplete, four variables had to be excluded (occipitonasal and postpalatal lengths, zygomatic breadth, and height of braincase could not be measured; fig. 24). Symbols: filled triangles  =  northern peninsula (N  =  10); empty triangles  =  Bumbarujaba (N  =  7); empty circles  =  Sungai Oha Kecil + Sungai Sadaunta (N  =  146); filled circles  =  Danau Lindu + Gunung Kanino (N  =  42); empty squares  =  Gimpu (N  =  3); left-pointing empty triangles  =  Gunung Tambusisi (N  =  6); asterisks  =  Pegunungan Mekongga (N  =  11); empty diamonds  =  Lalolei (N  =  3); filled squares  =  Gunung Balease (N  =  3); star  =  single specimen from Bakubakulu. Arrows and abbreviations identify scores for holotypes: b  =  brevimolaris; c  =  chrysocomus; k  =  koka; n  =  nigellus (empty triangle); r  =  rallus. See table 23 for correlations (loadings) of variables with extracted components and for percent variance.

Plotted results of discriminant-function analysis provide a sharper resolution of geographic variation in morphometric traits among samples. Individual specimen scores projected on first and second canonical variates form two slightly overlapping constellations in the scatter plot that include holotypes of brevimolaris, koka, nigellus, and rallus (fig. 27, upper graph) and the plot incorporating those holotypes as well as that for chrysocomus (fig. 27, lower graph). The largest and densest cluster of scores in the right half of both scatter plots represents the 188 specimens from my transect in the northern part of the west-central mountain block (Sunga Oha Kecil + Sungai Sadaunta combined with Danau Lindu + Gunung Kanino), the rat from Bakubakulu just north of my transect, and the three individuals from Gimpu, south of the transect and also in the west-central region. Specimens from along the transect were collected at sites in mostly unbroken forest extending from Sungai Oha Kecil at 320 m to Gunung Kanino at 1524 m, an elevational range embracing habitats in tropical lowland evergreen rain forest and lower montane forest. It is not surprising that their scores form a single cluster, and one that also embraces scores of the specimen from Bakubakulu and the three from Gimpu.

Fig. 27.

Specimen scores representing 10 population samples of Bunomys chrysocomus projected onto first and second canonical variates extracted from discriminant-function analysis of 16 cranial and two dental log-transformed variables. Upper graph: All variables are represented and scores for four of the five holotypes are present. Lower graph: The holotype of chrysocomus is added, but its skull is incomplete so four variables are omitted (occipitonasal and postpalatal lengths, zygomatic breadth, and height of braincase could not be measured; fig. 24). Symbols: filled triangles  =  northern peninsula (N  =  10); empty triangles  =  Bumbarujaba (N  =  7); empty circles  =  Sungai Oha Kecil + Sungai Sadaunta (N  =  146); filled circles  =  Danau Lindu + Gunung Kanino (N  =  42); empty squares  =  Gimpu (N  =  3); left-pointing empty triangles  =  Gunung Tambusisi (N  =  6); asterisks  =  Pegunungan Mekongga (N  =  11); empty diamonds  =  Lalolei (N  =  3); filled squares  =  Gunung Balease (N  =  3); star  =  single specimen from Bakubakulu. Arrows and abbreviations identify scores for holotypes: b  =  brevimolaris; c  =  chrysocomus; k  =  koka; n  =  nigellus; r  =  rallus. Correlations (loadings) among variables with extracted canonical variates and percent variance are listed in table 24.

Slightly separated from the dense cluster of points representing specimens from the west-central region are those scores for samples from the northern peninsula (Bogani Nani Wartabone National Park); Bumbarujaba, near the southern end of the northern peninsula; Gunung Tambusisi, at the western margin of the eastern peninsula; part of the sample from Gunung Balease on the eastern margin of the west-central mountain block; Pegunungan Mekongga in the southeastern peninsula, and Lalolei in lowlands adjacent to the Mekongga highlands. The position of scores along the first canonical variate representing these samples reflects their slightly larger braincase and bulla; longer diastema, incisive foramina, and molar row; and narrower rostrum, zygomatic plate, and mesopterygoid fossa (see moderate to large positive and negative loadings in table 24) compared with those samples from the west-central mountain block, distinctions reflected in univariate summary statistics (tables 21, 22).

The association of four of these five population samples relative to the four from the west-central region in the scatter plot is also portrayed in the clustering pattern based on Mahalanobis distances squared as a measure of phenetic resemblance (fig. 28). Samples from the northern peninsula, Bumbarujaba, Gunung Tambusisi, and Pegunungan Mekongga form a cluster separate from that containing the samples from Danau Lindu + Gunung Kanino, Sungai Oha Kecil + Sungai Sadaunta, Bakubakulu, and Gimpu. This pattern of phenetic relationships among population samples also appears in the cluster diagrams where samples of all phenetic members of the B. chrysocomus group are compared (fig. 49) as well as the phenetic alliances among all species of Bunomys diagrammed in figure 21. The two clusters for B. chrysocomus describe a distributional pattern in which one group of samples is from a region extending from the northern peninsula onto the western end of the eastern peninsula and ending on the southeastern peninsula (population samples are from thenorthern peninsula, Bumbarujaba, Gunung Tambusisi, and Pegunungan Mekongga), and the other samples are from mountains and valleys in the west-central region (Danau Lindu + Gunung Kanino, Sungai Oha Kecil + Sungai Sadaunta, Bakubakulu, and Gimpu).

Fig. 28.

Upper diagram: Phenogram generated from UPGMA clustering of squared Mahalanobis distances among 10 population sample centroids for Bunomys chrysocomus, as derived from discriminant-function analysis. Lower diagram: Specimen scores representing B. chrysocomus projected onto first and second canonical variates extracted from discriminant-function analysis of 16 cranial and two dental log-transformed variables. Scores represent four samples: (1) combined population samples from northern peninsula, Bumbarujaba, Gunung Tambusisi, Pegunungan Mekongga, and Lalolei (empty triangles; N  =  36); (2) series from Sungai Oha Kecil + Sungai Sadaunta, Danau Lindu + Gunung Kanino, and Gimpu (crosses; N  =  192); (3) Gunung Balease (filled triangles; N  =  3); (4) Bakubakulu (filled square; N  =  1). The upper graph in figure 27 shows the same overall distribution of scores but with separate population samples identified. See table 24 for correlations (loadings) among variables and percent variance explained.

Samples from Laolei and Gunung Balaese, not mentioned above, deserve highlighting. The three Laolei animals are from lowlands (300 m) adjacent to Pegunungan Mekongga. Their individual scores in the canonical variate ordinations group with those representing specimens in samples from the northern peninsula, Bumbarujaba, Gunung Tambusisi, and Pegunungan Mekongga (fig. 27). Close association with Pegunungan Mekongga should be expected considering the near geographic proximity of Lalolei to that highland region, but in the Mahalanobis diagram, the sample forms an independent link to both that cluster and the one containing samples from the west-central region (figs. 28, 49). In different iterations of the Mahalanobis diagram where small samples of B. chrysocomus were subtracted or samples of other species of Bunomys were added (not illustrated here), the Lalolei sample either remains isolated or links with the group of population samples containing Pegunungan Mekongga. A larger sample from the lowlands adjacent to the Mekongga massif is needed to obtain a better estimate of the population mean and more reliable assessment of its phenetic affinity to other population samples.

Results of the multivariate analyses of cranial and dental variables described above suggest some interruption of gene flow between populations in the west-central region and those on the northern and southeastern peninsulas (geographic variation within a single species) but not complete genetic isolation (two species very similar in morphological attributes). In this context, the samples from Gunung Balease and Bakubakulu provide insights. Gunung Balease lies on the eastern margin of the west-central mountain block (locality 43 on the map in fig. 22). Collecting efforts there during October, 2010, produced four adult B. chrysocomus, but only three have intact skulls and these three form the population sample used in the multivariate analyses (see table 2). Mitochondrial cytochrome-b sequences were obtained from three specimens and analyzed in Jim Patton's laboratory. One rat was collected at Bakubakulu (locality 6 on the map in fig. 22) in the Puro Valley, which is just north of my transect; no DNA sequences are available for it.

In the canonical variate ordinations (fig. 27), scores for two of the animals from Gunung Balease cluster with scores representing the northern and eastern population samples (northern peninsula, Bumbarujaba, Gunung Tambusisi, Pegunungan Mekongga, and Lalolei), but the third score falls in the constellation formed by points identifying samples from the west-central mountain block (Sungai Oha Kecil + Sungai Sadaunta, Danau Lindu + Gunung Kanino, Bakubakulu, and Gimpu). In the Mahalanobis distance (squared) cluster, the sample from Gunung Balease either links with the sample from Pegunungan Mekongga (figs. 21, 28) or is independent, without a discrete link to either of the two primary clusters of population samples (fig. 49) depending on what species are used in the analyses.

Both principal-components and canonical variate ordinations place the score for the specimen from Bakubakulu in the heart of the cloud of scores representing the samples from the west-central mountain block (figs. 26, 27). In the Mahalanobis cluster diagrams, no matter the composition of the species, the specimen always links with the sample from Sungai Oha Kecil + Sungai Sadaunta (figs. 21, 28, 49). This placement is significant in that Bakubakulu (01°07′S, 120°00′E) is not far from Tangoa (01°10′S, 120°05′E), also in the Puro Valley, where Chris Watts collected specimens and preserved tissues from which DNA sequences could be extracted. Attached to the Tangoa specimen is a cytochrome-b sequence available from GenBank (ABTC 65755; I have not seen the voucher or any of Watts's material from the Puro Valley), and I am assuming it could easily represent cytochrome-b sequences for the population of B. chrysocomus in the Puro Valley, including the sample from Bakubakulu.

Placements of the scores for three specimens from Gunung Balease and the animal from Bakubakulu in multivariate space are summarized in the lower canonical-variate scatter plot in figure 28. The left cloud contains scores for the northern and eastern population samples combined, the right assemblage represents combined samples from the west-central region. The two constellations marginally overlap, the sample from Gunung Balease overlaps each large cluster, and the score for the Bakubakulu rat is nestled among those for the animals collected in the west-central region. The molecular distance between the cytochrome-b sequence from the Tangoa animal (which I use as a stand-in for the Bakubakulu rat, that is, drawn from the same population) and those from Gunung Balease is about 1% (the molecular trees were provided by Jim Patton and Kevin Rowe), “which is well within what might be viewed as a ‘typical’ intraspecific range” (J.L. Patton, in litt., 2011; see also Baker and Bradley, 2006). The meager genetic data combined with the larger set of information revealing morphometric variation among samples suggests that samples available to me represent a single species. There are homogeneous populations in some areas (the west-central mountain block, for example) that are somewhat different in their genetic and morphometric attributes from populations in other regions of the island, but the geographic variation seems to be contained within B. chrysocomus. This is a reasonable hypothesis but certainly one that requires testing by analyzing DNA sequences from multiple genes (mitochondrial and nuclear) derived from far more geographic samples, and also looking at variation in cranial and dental variables in large samples from currently unsampled geographic regions. Expansive stretches of the island have not been surveyed for the species: most of the northern peninsula, the Pompango mountains east of Danau Poso, the entire eastern peninsula, most of the west-central mountain block south of the Danau Lindu area, and the remnants of forest on the southwestern arm require focused survey efforts. Current samples are unequal in size (available series of specimens from Bogani Nani Wartabone National Park, Bumbarujaba, Gunung Tambusisi, Pegunungan Mekongga, and Lalolei are small, ranging from 3 to 11 specimens for a total of 37) and univariate mean differences among all the population samples are not great (tables 21 and 22). Available samples are unequal in composition of adult age categories and future inquiries into patterns of geographic variation should be based on comparisons among similar adult age classes.

Of course, analyses of gene sequences in samples from the same regions from which my samples were obtained, and analysis of morphometric traits in samples from regions where specimens are now not available, may produce a different pattern of phenetic and genetic alliance among regional populations that is not revealed by my present analyses.

From my study of variation in cranial and dental variables emerged another pattern of phenetic relationships among some of the population samples that are instructive within the context of contrasting samples from montane habitats in different regions of Sulawesi. Are montane populations in different areas isolated by stretches of lowland forest closely related to one another or is a particular population in montane forest more closely related to the population inhabiting the adjacent lowlands covered by tropical lowland evergreen rain forest? My analyses points to a closer tie (phenetically and presumably genetically) between highland and immediately adjacent lowland populations than among distant montane regions, at least in comparison between samples from the core of the island and those from the southeastern peninsula. In the west-central region, the specimens from along my transect come from lowlands and middle elevations along the Sungai Oha Kecil, Sungai Sadaunta, and in the valley of Danau Lindu in tropical lowland evergreen forest, and from higher elevations on nearby Gunung Kanino in lower montane forest. Scores for these specimens are tightly packed in mutilvariate space as reflected by first and second canonical variates and phenetic clustering based on squared Mahalanobis distances among centroids (figs. 27, 28), which suggests uninhibited gene flow between the lowland to middle-elevation populations (Sungai Oha Kecil, Sungai Sadaunta, and Danau Lindu) and the one in the adjacent highlands (Gunung Kanino).

None of the scores for the specimens in “Danau Lindu + Gunung Kanino” are close to the scores representing the sample from Pegunungan Mekongga on the southeastern peninsula. In the canonical-variate ordinations, scores for individuals from that mountain range fall closer to the points representing the sample from Lalolei, located in the lowlands south of Pegunungan Mekongga. The samples from the southeastern peninsula are small and none come from a transect linking samples from lowland tropical evergreen rain forest with montane forest habitats on the Mekongga range, but the analysis suggests a stronger phenetic (and inferentially genetic) link between lowland and highland populations on the southeastern arm than between the Pegunungan Mekongga population and those in montane habitats of the west-central region.

In this context of montane samples one other small group of specimens deserves attention. The highest point from which a sample of B. chrysocomus has been collected is 2200 m on Pegunungan Latimojong, the highlands forming the southern margin of the west-central mountain block. That series is not included in the multivariate analyses of cranial and dental measurements. Of the seven specimens available to me, one is an old adult, two are adults, one is a young adult, another is a very young adult (in fresh adult coat), and two are juveniles. I could obtain a complete set of measurements from only one of the young adult skulls (table 22); two from the other adults are in fragments and one skull is missing. The juvenile skulls and that from the very young adult, although complete, are too young to include in the multivariate analyses. Values for cranial and dental measurements from the intact young adult skull fall within the range of variation seen in the other geographic samples of B. chrysocomus from the mountain block (tables 21, 22). Crown lengths of maxillary molar rows and breadths of first upper molars, which could be measured in five of the seven skulls, range from 6.1 to 6.2 mm and 2.0 to 2.1 mm, respectively, also well within the range of variation for these two variables in the other three population samples from the west-central region. Dorsal and ventral coats of the five adults are long (15–20 mm), and browner than in most other population samples, but with a sheen and silky texture resembling most other examples of B. chrysocomus.

In summary, geographic variation in qualitative traits associated with the skull and molars, or with any aspects of fur traits (texture, thickness, and coloration), tail pattern, or dimensions of combined head and body, ears, feet, or tail is not readily apparent or lost within the variation seen in any large single sample. By contrast, intersample variation in measured dimensions of crania and molars is present, as shown by discriminant-function analyses. Revealed are two primary sets of samples: one is from the west-central mountain block, the other contains samples from the northern peninsula, western margin of the eastern peninsula, and the southeastern arm of the island. Absolute and proportional differences among univariate means responsible for the geographic patterns are modest and usually undetectable by visually comparing skulls and dentitions (using specimens of relative comparable age). The degree of difference between the two geographic clusters in Mahalanobis distance units is far less than the magnitude separating the morphologically similar and montane B. coelestis, B. prolatus, and B. torajae, n. sp., from the population samples representing B. chrysocomus (fig. 49).

Natural History

Information presented here is organized under habitat, diet, burrows, nests, development of young, testes and sperm, and forest pathways.

Habitat: Bunomys chrysocomus was commonly encountered along the transect area extending from Sungai Oha Kecil to Gunung Kanino in forest formations embracing environs in tropical lowland evergreen rain forest (figs. 29–Fig. 30.31, 96–Fig. 97.98) and lower montane forest (figs. 32, 79) through the elevational range from 320 m to 1555 m (fig. 103). More specimens of B. chrysocomus (323 examples) were collected than any other murid, all but five were taken in lowland tropical evergreen rainforest habitats, and those five were trapped in lower montane forest (fig. 103). Only Paruromys dominator (306 specimens) came close to the dominance of B. chrysocomus along the transect line, followed by Rattus hoffmanni (201 examples) and Rattus facetus (161 specimens).

Fig. 29.

Tropical lowland evergreen rain forest along the Sungai Sadaunta, 750–850 m (in 1974). Typical forest composition on terraces just above the stream: dense undergrowth of shrubs and tree saplings, woody vines looping through the understory. Beneath the dense cover, the ground is wet, the air cool. Most Bunomys chrysocomus were trapped in this kind of stream terrace habitat, either on the ground beneath the shrubs, alongside decomposing, moss-covered trunks and limbs lying on the terrace, or among moss-covered rocks. Bunomys karokophilus, n. sp., was encountered in similar habitat.

Fig. 30.

Traps set (1974) below the stream terrace on wet and rocky banks of the Sungai Sadaunta beneath dense streamside vegetation yielded Bunomys chrysocomus. Rats were caught along the margin of the terrace (upper part of the photograph); on rocks beneath the ferns, rattan rosettes, and broad-leafed monocots; and on rocks only a few inches from the water's edge.

Fig. 31.

Tropical lowland evergreen rain forest along the Sungai Sadaunta, 700 m (in 1976). Examples of Bunomys chrysocomus were caught amid the rocks in the foreground, deep within the forest, and occasionally on trunks and branches spanning the stream. Similar dense streamside forest and bridging trunks and limbs from old treefalls characterize much of the habitat along the Sungai Sadaunta where B. chrysocomus as well as B. karokophilus, n. sp., were encountered (see Natural History in account of B. chrysocomus).

Fig. 32.

Lower montane rain forest on Gunung Kanino, 1556 m, 1973. During different nights, Bunomys chrysocomus, B. penitus, and Rattus hoffmanni were trapped in a damp runway beneath the large decomposing and moss-covered chestnut trunk shown here. This is the highest spot where I encountered B. chrysocomus, which proved to be rare in this lower montane habitat as compared with the higher concentrations at lower elevations in tropical lowland evergreen rain forest (see fig. 103). Bunomys penitus, which extends down to the lower limit of lower montane rain forest at 1285 m, was common in the forest here and the only species of Bunomys found at elevations above 1556 m and all the way to the summit of Gunung Nokilalaki (see fig. 103). Paruromys dominator was frequently encountered in the forest surrounding the decaying trunk, Maxomys musschenbroekii and Rattus facetus were trapped nearby. Prosciurillus topapuensis and P. murinus were the squirrels usually seen, but the large reddish Rubrisciurus rubriventer was rarely encountered.

Nocturnal and terrestrial, all but two specimens were caught on the ground. The exceptions are one taken on a woody vine about 2 ft above ground, another on a vine 3 ft above ground; both places were easily accessible from ground level.

Examples of the microhabitats in which we trapped B. chrysocomus are described in table 25 (the descriptions are selected to cover the range of habitats trapped and not to document where every rat was trapped). Mean ambient air temperatures ranged from 61.1° to 80.9° F in the lowland forest from Sungai Oha Kecil (290 m) to Sungai Tokararu (1150 m), with high relative humidity; 58.4° to 68.9° F and comparable relative humidity characterized lower montane forest on Gunung Kanino (table 3).

Mature tropical lowland evergreen rainforest habitats where we encountered most of the B. chrysocomus along the transect is floristically species rich. While our floristic survey was not exhaustive, we either collected samples of or identified approximately 350 species of trees (canopy species, emergents, and understory trees), nine species of solitary palms (in Areca, Pinanga, Pigafetta, Arenga, Caryota, and Licuala), a dozen species of rattan (Calamus Korthalsia, and Daemonorops), half a dozen species of terrestrial pandans (Pandanus) and climbing pandans (Freycinetia), several kinds of gingers, a few lilies, two species of native bananas (Musa), dozens of shrubs, two kinds of bamboo, and some woody and herbaceous vines.

Most B. chrysocomus were encountered in steep and wet hillside forest, on forested terraces bordering streams and rivers, along streams at the waters edge, and occasionally on decaying tree trunks and limbs spanning streams (figs. 29, 30).

Vegetation bordering streams the size Sadaunta and its tributary Pormina at about 700 m (fig. 31) form good examples of bank and terrace habitats. The waterways may be open in spots but usually have a broken or partial canopy shading them. A low partial or complete canopy over the stream is provided by half a dozen species of understory figs (which include Ficus lepicarpa, F. minahassae, F. adenosperma, F. obscura, F. nervosa, F. geocarpa among others) that line the banks. These figs are the most common small tree along the streams and a few of them also grow back on terraces and hillsides. Their crowns, coming from each side of the stream sometimes intertwine over it and in places are connected by looping and coiling woody vines. Growing up through the figs as tall emergents are Wanga palms (Pigaffetta filaris), some Lekotu (Duabanga moluccana), the common Leutu (Pometia pinnata), and scattered Leda (Eucalyptus deglupta). At spots, the Wanga palms are dense enough to form a high canopy. Beneath the Wanga palms and tall trees are scattered ground and tree ferns; the palms Korthalsia celebica, Arenga undulatifolia, Areca vestiaria, Caryotis mitis, and the occasional Pinanga sp.; bananas (two species of Musa) that form groves in forest openings; the understory tree Semecarpus sp.; dense shrubs mixed with tall waist-high ground ferns, gingers, Pandanus sp., and a variety of broad-leaved monocots. Decaying wet tree trunks and limbs clutter the banks, here and there bridging the stream.

Mature forest at the level where Sungai Pormina joins the Sungai Sadaunta, about 700 m, is comprised of many species of large and old trees, some forming the high canopy, others emerging above it, and is characteristic of lowland and middle elevation forest along the transect. On the higher terraces back of the streams and base of the steep hills, for example, Dysoxylum densiflorum, Magnolia vrieseana (with boles 6 ft in diameter at waist level), Ficus magnifolia (4 ft diameter near base), Ficus cordatula, Octomeles sumatrana, Pterospermum celebicum, Aglia argentia, Canarium sp., and Palaquium obovatum are some of the common big trees, along with scattered strangler figs (Ficus sp.). Commonly encountered understory trees are Dillenia serrata, Pangium edule, Macaranga sp., Siphonodon sp., and the laurels Litsea and Alseodaphne. Most of the terrace species extend onto the hillsides, but there the most common high-canopy former is usually Mussaendopsis beccariana. Scattered oaks (Lithocarpus sp.), walnut (Engelhardtia serrata), Calophyllum sp., the occasional ebony (Diospyros macrophylla), old strangler and solitary figs also contribute to the canopy. Recognizable understory trees are Nauclea puberla, Timonius koordersii, Pouteria maclayana, Elaeocarpus sp., nutmegs (Knema, Myristica), Artocarpus sp., and Cinnamomum sp. The sugar palm Arenga pinnata is scattered through the forest as are the palms Areca vestiaria, Pinanga sp., and Caryota sp. Here and there are clumps of pandans and groves of Casurina in open spots.

Bunomys chrysocomus, although commonly found in wet and shaded parts of the forest, is also one of the few murids found in the drier steep hillside forest and ridgetops well away from streams. For example, we set a trapline in steep hillside forest away from any streams or wet ravines from 763 to 1068 m above one of our camps and caught 40 B. chrysocomus and three Paruromys dominator. Other murid species were in these hillside forests but only in damper situations along small tributary brooks and the sides of wet ravines.

Most of the B. chrysocomus came from intact primary forest, but we did trap a few in other habitats. One was scrubby secondary growth on landslips and clearings made by tree-falls in intact old-growth forest. An example was a place on a high terrace along the Sungai Sadaunta where the mature forest was interrupted by a 40–50 ft square area covered by regenerating growth 10–20 ft high concealing a fallen canopy tree, now shattered into decaying limbs and trunk partly covered with moss. Low ground shrubs, bananas, clumps of ginger, dense thickets of ground ferns and spiny rattan rosettes, young solitary palms and pandans, tree seedlings and saplings, all threaded by herbaceous and woody vines, are typical elements of this secondary growth.

Another was a patch in tall mature forest near the village of Tomado where the understory had been thinned by villagers to plant coffee trees. Huge, tall canopy and emergent trees were left from the old-growth forest to shade the coffee. Among the most prominent of these were strangler and nonstrangler figs (Ficus sp.), Uru (Magnolia vrieseana), Kume (Palaquium obtusifolium), Torode (Pterospermum celebicum), Benoa (Octomeles sumatrana), Lekotu (Duabanga moluccana), and Tahiti (Dysoxylum densiflorum).

A third place was scrubby ecotone between high forest and meadow or garden (table 25).

Diet: Bunomys chrysocomus consumes invertebrates, small vertebrates, and some fruit, but not fungi (table 13). At several camps I kept a few adults captive (each for 3–4 weeks) and offered them a variety of foods gathered from the forests. Invertebrates and vertebrates were the items most voraciously consumed. All were very selective about fruits, accepting only a very few of the wide range offered. Below I present the foods eaten by B. chrysocomus drawn from my observations of captive animals and study of contents extracted from stomachs.

Earthworms (oligochaetes)—A rat aggressively yanked an earthworm from my fingers with its incisors before transferring the worm to its front feet. The rat placed one end of the worm in its mouth, cutting it into segments and pulled the worm through its paws until entirely consumed (the remains of earthworms in most of the stomachs surveyed consisted of short unchewed pieces); the action is to pull, bite off a piece, chew it, swallow, then bite off another segment. No attempt was made to seek the anterior end of the worm (specialized Sulawesi murid vermivores such as Echiothrix manipulate the earthworm so it could ingest the anterior portion first and hold the body tight so most of the gastrointestinal contents are forced out of the worm's anus onto the ground; see Musser and Durden, 2014), which resulted in the worm's gastrointestinal contents covering the muzzle and front feet.

All sizes of earthworms were offered and accepted. I had been feeding one captive male small earthworms (2–3 inches long) and one day placed a very large worm (6 inches long, about 3/8 inches in diameter) in the cage. He promptly jumped on the worm but could not initally subdue it, attacking one end and then the other. Repeated attacks caused the worm to eject a clear fluid 8–12 inches into the air from pores along its body. At first irritated, the rat left the worm, cleaned its muzzle, but quickly renewed its attack. Finally he sank his incisors into the last 2 inches of the worm and managed to separate and eat that short segment. Although captive rats ate large earthworms, I found only segments of small worms in stomachs. Smaller earthworms are likely more commonly taken and can be eaten quickly with less exposure of the rat to predators. Earthworms averaging 2 inches long and 1/8 inch in diameter were consumed in 3 to 14 seconds by captive rats; worms 4–5 inches long and 1/8 to 3/16 inches diameter were completely ingested by the rats after 57 to 145 seconds. One rat used 5 minutes to eat a 6 inch long earthworm that it first had to bite into several pieces.

Snails—Managing snails followed a typical behavior by all captive B. chrysocomus. Each snail was grabbed with the incisors and transferred to the front feet. The rat usually used 30–60 seconds to turn the shell over and over, trying several spots with the incisors, all the while sniffing the shell. Eventually it began biting off pieces from around the aperature until enough shell had been removed to expose the snail's body; sometimes the rat turned the shell and bit into the side, removing bits of shell until the enclosed body was exposed. Once accessible, the rat pulled away a bit of the flesh, ingested it, bit away more shell, pulled and ingested more of the tissue, and proceeded in this manner until the entire snail was consumed. After the snail's body was extracted the remainder of the shell was discarded. Sometimes after removing just a few pieces of shell, a rat managed to extract the entire snail. The shell fragments were not ingested, and I never found pieces in the stomachs I surveyed; I did find an operculum along with the partly digested remains of the snail in a few stomachs.

Most of the snails accepted by the rats were small, ½ to 1 inch in diameter and a quarter of an inch thick. I often encountered empty shells this size and some up to 1.5 inches in diameter lying among the leaf litter and debris on stream banks and terraces; all were breached.

Insects and other arthropods—Moths, cicadids, grasshoppers, katydids, crickets, praying mantises, cockroaches, and wasps were provided and all consumed by captive adult rats. Each rat used its incisors to pull the insect from my fingers, transfered it to the front feet and manipulated it until the head was up. It then bit the insect's head and proceeded to voraciously consume head, thorax, and abdomen—wings and legs were discarded. Only heads of the wasps were eaten. Larger insects, such as praying mantises, were propped against the cage floor and consumed beginning with the head.

One particular rat never seemed satisfied with the number of insects provided. One morning I gave it 12 large crickets (up to 2 in. long), which were quickly dispatched and eaten; afterward it kept probing the mesh with its muzzle seeking more. Another rat ate 17 cockroach nymphs (1–1.5 in. long, half an inch wide) at one feeding, consuming one after the other, averaging 90 seconds per nymph. A different rat ate five large katydids (3–4 in. long) in one evening, taking 6–8 minutes to consume each insect. The head, thorax, abdomen, and thicker portions of the hind legs were ingested, wings and other legs were discarded.

A juvenile given small grasshoppers and crickets ate them in much the same way as did the adult rats. Often, however, the young rat fumbled about trying to catch and dispatch a grasshopper by the head in which case the insect would escape and hop about the cage with the little rat in hot pursuit. Once caught and eventually killed the grasshopper was eaten beginning at the head and finishing with the abdomen; only wings and legs were discarded, the typical feeding behavior of adult rats.

Contents of the stomachs I surveyed record additional kinds of insects and other arthropods consumed by B. chrysocomus: macrolepidopteran caterpillars, rhinotermitid termites, adult and larval beetles, ants, spiders, and geophilomorph centipedes (table 13).

Other invertebrates—I offered small freshwater crabs found near streams to B. chrysocomus—all were ignored.

Vertebrates—I gave small frogs and a small lizard to the captive adult B. chrysocomus. One rat was satisfied with three small frogs (1 to 1.5 inches long) at any single feeding bout. The rat grabbed the head, bit it, which immobilized the frog, then turned the frog around and began eating the legs. Both legs were usually eaten first, sometimes the body, but the head was discarded. Sometimes the rat would begin chewing on the head, stop and turn to the legs, ignoring the head. A different rat consumed all but a few foot bones of a frog 2.5 inches long. A juvenile rat seemed less familiar with frogs and those placed in its cage often escaped. Once the frog was subdued, the rat chewed on the hind legs without any attempt to first bite the head to immobilize the frog.

Small frogs are likely one of the most common small vertebrates encountered in the wet forests along streams and sheltered hillsides, the habitats where B. chrysocomus was commonly trapped. It was in those places that I collected the frogs fed to the rats.

In another rat's cage I placed a small lizard (head and body 2 in. long, tail about 4 in. long). The rat immediately pounced on the lizard, bit the head, and consumed the entire animal, proceeding from head to tip of the tail, leaving nothing.

Fruit—I offered captive rats a variety of fruits. Those from the following species of canopy and understory trees were rejected: Chisocheton, Garcina, Planchonella, Knema, Aglia, Palaquium, Magnolia, Myristica, Eleocarpus, Siphonodon, Lithocarpus, and some Ficus. Fruit from several species of woody vines were consistently rejected as well as fruits from three species of common understory palms, Areca vestiaria, Pinanga ceasia, and Pinanga sp.

Only a few fruits were eaten by the rats. Two species of wild bananas (Musa) occur in tropical lowland evergreen rain forest throughout my transect area; the white, sticky pulp of both species was readily accepted and consumed by all captive B. chrysocomus; the skin along with the large and hard seeds were rejected. Pulp surrounding seeds of fruit from the canopy tree Himantandra belgraveana was eaten, as were small red berries from an understory shrub, and large and small figs from different species of understory Ficus. Remains of fig were the most common fruit found in contents of stomachs. Fruit from the wanga palm Pigafetta filaris was always accepted. The rats neatly removed the scaly covering, ate the transparent jellylike pulp and discarded the single hard black seed. One rat ate the gelatinous pulp that encloses the seeds of a ginger.

Stomachs examined rarely contained only fruit. The content of stomachs from two rats trapped at Tomado is illustrative. One full stomach contained remains of a fig with large seeds and seeds from another kind of fruit; several moderately large cursorial beetle lavae, pieces of a cockroach numph, and one geophilomorph centipede were mixed with the masticated fruit. Another stomach was distended with reddish-brown fruit pulp, remains from two kinds of figs, a fruit with hard orange oblong seeds, and a different fruit with small striped seeds; one well-chewed earthworm, fragments of a young cockroach instar, and remains of a few rhinotermitid soldiers constituted the invertebrate remains.

Stomachs from two rats illustrate contents consisting of primarily invertebrates and little fruit. An animal from Tomado had a stomach packed with rhinotermitid soldiers and workers, and also held remains of a few small adult beetles, a cockroach nymph, geophilomorph centipede, and pulp from figs. The stomach from a rat trapped on the Sungai Sadaunta was distended with remains of arthropods: many rhinotermitid termites and small adult beetles, pieces of larger adult beetles, two kinds of small beetle larvae, one geophilomorph centipede, one macrolepidopteran caterpillar, orthopterans, several cockroach nymphs, and a few ants; a bit of tan-orange pulp and some small pieces of tough rind comprised the meager remains of fruit.

Fungi—I offered captive rats samples of the two kinds of shelf or ear fungi so readily consumed by Bunomys karokophilus, n. sp. (see that account), the purplish Auricularia delicata and white A. fuscosuccinea. Both were consistently rejected. Offerings of cap-and-stem fungi were also ignored.

Overview—Bunomys chrysocomus is an aggressive, quick and agile predator of arthropods, earthworms, snails, and small vertebrates. Any insect or frog loose in a cage was immediately chased and caught in a blur of movement; usually a rat grabbed the prey with its incisors, occasionally pinning it to the cage floor with its front feet. The animals are also adept at nosing through leaf litter and debris on the forest floor. I watched a released male nose about in the leaf litter until only half the body was visible, and occasionally dig, then nose about again, dig, and when he located something stop and eat. Most of the work was done with his head and nose, pushing into the litter and sniffing about, sometimes digging or pulling back debris with the front feet. He also ambled over the litter, sometimes making quick jumps of a foot or so. Bunomys chrysocomus has access to prey living on the surface of the forest floor (leaf litter, exposed soil surface); within the leaf litter and ground debris; in decaying trunks and limbs of treefalls; on the surface of green leaves attached to stems and branches freshly detached from trees during storms and lying on the forest floor; and on the basal stems of forbs, shrubs, trees, and palms. See the account of B. andrewsi for an inventory of the range of invertebrates and small vertebrates found in these places.

The contents of a stomach from a rat trapped at Tomado summarize the range of foods ingested by B. chrysocomus. The distended stomach contained pulp and skin from an unidentified fruit; several earthworms chopped into segments (contents of the gastrointestinal tract present within each segment, unlike remains found in stomachs of Echiothrix in which the worm segments are hollow); several ants; at least one cockroach nymph; one “hairy spider” (long hairy legs and part of thorax); at least four kinds of beetle larvae (one small with rows of markings and “proleg” type feet, many that are small and intact [5–8 mm long], a few small legless larvae, and thoracic remains from long-legged cursorial larvae); several large margarodid scale insects; small adult staphylinid beetle; skin fragments from a macrolepidopteran caterpillar; and a few rhinotermitid workers. The combination of invertebrates would have been found in leaf litter, decaying wood, beneath rocks, and in soil beneath moss and decaying wood.

I insert a final statement about the reaction by captives to food. All the captive adult B. chrysocomus (as well as the examples of B. andrewsi, B. penitus, and B. karokophilus, n. sp.) unambiguously either accepted or rejected different foods I offered. Of those rejected, particular items were especially distasteful to the rats (some fruits and fungi) and their first response was to run about the cage rubbing their lips and chin on pieces of wood, leaves, or even the cage floor. Then a rat would use its tongue to moisten its palms to clean the lips and chin.

Burrows, nests, and young: Bunomys chrysocomus nests in burrows below ground. I have seen burrow openings in the alcove between buttresses of a tree growing on the terrace of a stream; runways and entrances to burrows along a 6 inch high tree root growing above ground; and under jumbles of rocks lying on a stream terrace just above water level. At about 8:00 a.m. on a ridge terrace at about 1000 m I saw an adult B. chrysocomus with two young running around the base of a tree. They heard me. The adult female stopped by a raised root and sat there. The two young ran, each in a different direction, about 2 ft from the root and froze, looking at me. Eventually the juveniles ran off into the undercover and the adult disappeared down a burrow beneath the root. At another time I captured a rat in a live trap that had been placed on the mud and leaves just above a stream; when released, it peered out of the trap, finally ambled away, then slowly ran uphill about 4 ft to disappear into a burrow beneath a pile of small rocks partially covered with soil and vegetation.

My notes recording construction of nests are summarized here. I placed dry leaves in a small cage with an adult male caught along the Sungai Sadaunta. He arranged these into a globular nest with a deep cup-shaped depression in which he slept. None of the leaves were folded or cut, simply arranged to form the nest. Another rat kept in a small cage on the ground reached between the mesh to pull in pieces of dry stems and leaves of grass and sedges, small forbs, and plant debris. The green, growing plants would be pulled through the mesh, cut and placed on the growing pile of vegetation on which it slept in a depression during the day. At night the rat shoved the debris around with its nose, often burrowing into the pile, and occasionally flushing an insect, which it quickly pounced on and ate.

One captive female kept constructing a nest using dry leaves in much the same way as described above. After about a week, she gave birth to two young. Their growth and interactions with the mother are summarized in table 26. One or two young is standard for B. chrysocomus and all the other species of Bunomys for which I have data covering litter size.

Testes and sperm: Body and testes weights (mass) along with sperm size was derived from two B. chrysocomus by Breed and Taylor (2000) and employed in an investigation of murines designed “to test the hypothesis that differences in relative testes mass, and perhaps sperm size, relate to interspecific differences in the amount of intermale sperm competition and in breeding systems.”

Forest pathways: Along my transect in the west-central region and in the Malakosa area, we always set traps on decaying tree trunks and limbs, and palm trunks bridging streams, creeks, and ravines. Traps were also placed on leafy limbs growing across streams. Squirrels used these live bridges as well as rotting and wet trunks and limbs spanning streams, but we caught rats only on the latter, not on the live limbs. By using the trunks and limbs, rats can scamper across streams and narrow rivers without getting wet. Wet fur is life threatening. Mist and fine droplets of water adhering to the end of the hairs can be shaken off without compromising the insulative capacity of the coat—the fur between hair tips and skin remains dry. If the rats accidentally fall into water or are forced to run through shallow parts of the stream the fur may become soaked and difficult to dry in an environment where the relative humidity is between 90% and 100%.

We saw firsthand the importance of keeping fur dry when occasional intense storms knocked over tents and cages in which we kept some B. chrysocomus. The rats were soaked, appeared to be stunned and made no attempt to dry their fur until hours later when the coat had partially dried. Then each rat tried to fluff the fur, but most of the coat remained matted and difficult to groom. Rats taken in live traps unprotected from nightly rains were sickly when we found them in the morning and did not recover.

Rats might scramble over rocks jutting above the water surface in shallow streams. We placed traps on such exposed rats but invariably caught only toads—no rats. This type of potential crossing is useless when the stream floods during heavy rains, which was usual during the time I worked in forests along the transect. Dead trunks and limbs connecting higher stream terraces usually were higher than flood level.

Ectoparasites, Pseudoscorpions, and Endoparasites

Sucking lice, fleas, ticks, chiggers, and mites are the groups of ectoparasites utilizing Bunomys chrysocomus as a host (table 14). Of the two species of sucking lice (Anoplura), Hoplopleura chrysocomi has been found only on Bunomys chrysocomus (Durden, 1990), but Polyplax wallacei also parasitizes Bunomys fratrorum and a species of Taeromys (Durden, 1987; Durden and Musser, 1991, 1992).TABLE 15

TABLE 14

Summary of Ectoparasite and Pseudoscorpion Records for Species of Bunomys^a (Published sources are referenced under Ectoparasites and Pseudoscorpions in the accounts of hosts.)

TABLE 15

Descriptive Statistics for Cranial and Dental Measurements (mm) Derived from Population Samples of Bunomys chrysocomus and B. fratrorum Mean ± 1 SD and observed range (in parentheses) are listed.

TABLE 16

Results of Principal-Components Analysis Comparing All Population Samples of Bunomys fratrorum and B. chrysocomus Correlations (loadings) of 16 cranial and 2 dental log-transformed variables are based on 332 specimens; see figure 18.

TABLE 17

Results of Discriminant-Function Analysis Comparing Samples of Bunomys chysocomus, B. coelestis, B. prolatus, B. torajae n. sp., B. fratrorum, B. andrewsi, B. penitus, and B. karokophilus n. sp. Correlations (loadings) of 16 cranial and 2 dental log-transformed variables are based on 660 specimens; see figure 20.

Six species of fleas (Siphonaptera) in five genera are recorded from Bunomys chrysocomus. In addition to B. chrysocomus, Sigmactenus alticola pilosus (Leptopsyllidae) also infests 14 other species of endemic Sulawesi murine rodents (Bunomys penitus, B. prolatus, and B. karokophilus, n. sp.; Margaretamys elegans; Maxomys hellwaldii, M. wattsi, and Maxomys sp.; Melasmothrix naso and Tateomys rhinogradoides; Paruromys dominator; Taeromys celebensis and Taeromys sp.; Rattus hoffmanni and R. facetus [recorded as R. marmosurus]), and the nonnative Rattus exulans (Durden and Beaucournu, 2000). Besides Bunomys chrysocomus, five endemic Sulawesi murids (Rattus hoffmanni; Bunomys penitus and B. karokophilus, n. sp.; Maxomys sp.; Paruromys dominator) and two nonnative rats (Rattus exulans and R. nitidus) are also hosts for Stivalius franciscae (Stivaliidae; Beaucournu and Durden, 2001). Gymnomeropsylla bunomydis (Pygiopsyllidae) parasitizes the Sulawesi endemic rat Maxomys wattsi as well as Bunomys chrysocomus. (Durden and Beaucournu, 2002). Nestivalius sulawesiensis (Pygiopsyllidae) is recorded from Bunomys chrysocomus and from Bunomys fratrorum, Maxomys hellwaldii and M. musschenbroekii, and Rattus facetus and R. hoffmanni (Mardon and Durden, 2003). Finally, Musserella, n. gen., species #1 and #4 (Pygiopsyllidae) resides not only on Bunomys chrysocomus, but also parasitizes eight other Sulawesi endemic murids (Bunomys penitus and B. fratrorum, Rattus hoffmanni and R. facetus, Paruromys dominator, Maxomys hellwaldii and M. muschenbroekii, and Taeromys celebensis) and the nonnative Rattus exulans and R. tanazumi (Durden, in litt., 2008).

Bunomys chrysocomus is host to immature stages (larvae and nymphs) of species in three genera of ticks (Acari: Ixodoidea): Amblyomma sp., Dermacentor atrosignatus and Dermacentor sp., and Haemaphysalis psalistos and Haemaphysalis sp. (Durden et al., 2008). Collectively, in addition to B. chrysocomus, members of these three tick genera have been collected from a suite of other mammal hosts living in Sulawesi: immature stages from shrews (the endemic Crocidura sp. and Crocidura elongata, and the commensal Suncus murinus), two species of bat (Nyctimene minutus and Rousettus celebensis), three endemic squirrels (Rubrisciurus rubriventer, Hyosciurus heinrichi, and H. ileile), 12 species of endemic murid rodents (Bunomys fratrorum and B. andrewsi; Margaretamys beccari; Echiothrix centrosa; Maxomys hellwaldii, M. musschenbroekii, and M. wattsi; Paruromys dominator; Taeromys sp.; Rattus hoffmanni, R. xanthurus, and R. facetus [recorded as R. marmosurus]), four nonnative murines (Mus musculus; Rattus tanezumi [recorded as R. rattus], R. argentiventer, and R. exulans), and adults from pigs (Sus celebensis and Babyrousa babyrussa, both endemics, and the domestic Sus scrofa), rusa (Rusa timorensis, nonnative), water buffalo (Bubalus bubalis, nonnative), humans, and domestic dog (nonnative) (Durden et al., 2008; Musser and Durden, 2014).

Two species of chiggers (Acari: Trombiculidae) are known to parasitize Bunomys chrysocomus. Walchiella oudemansi also parasitizes Bunomys fratrorum and the nonnative Rattus exulans (Goff and Durden, 1987; Whitaker and Durden, 1987). Leptotrombidium deliense has also been recorded from the endemic rats Bunomys fratrorum, Maxomys musschenbroekii, Paruromys dominator, Rattus hoffmanni, and Rattus xanthurus. Phoretic deutonymphs of one species of mite (Acari: Histiostomatidae), Histiostoma sp., have also been recorded as being attached to laelapid mites (Laelaps spp.) parasitizing Maxomys hellwaldii, M. musschenbroekii, and Rattus hoffmanni (Whitaker and Durden, 1987); as noted above, Laelaps sp. have also been recorded from B. chrysocomus (L.A. Durden, personal commun.).

The pseudoscorpion, Megachernes sp., has been found on Bunomys chrysocomus (W.B. Muchmore, in litt., 1986).

A trematode (Trematoda) and nematodes (Nematoda) constitute the endoparasitic records. The human blood fluke, Schistosoma japonicum (Strigeidida, Schistosomatidae), is a trematode that requires in its life cycle an oncomelanid snail as intermediate host, and a mammal as the definitive or reservoir host. In the valley of Danau Lindu, humans, along with their dogs and domestic livestock, are reservoirs for the parasite as are the native murid rodents Bunomys chrysocomus, Rattus facetus [recorded as R. marmosurus], Rattus hoffmanni, and Taeromys celebensis, and the nonnative Rattus exulans (Sudomo and Carney, 1974; W.P. Carney, in litt., 1974; see also Clarke et al., 1974; I identified the hosts).

Several reports record nematodes parasitizing “Bunomys chrysocomus” and “Bunomys prolatus,” but identifications of the hosts have to be verified (I have not seen the specimens). Specimens from Kabubaten Donggala identified as “Bunomys chrysocomus” and series from Lore Lindu said to be “B. prolatus” were found to be parasitized by the nematode, Syphacia rifaii (Oxyurida, Oxyuridae), which is presumed to infect only species of Bunomys (Dewi and Hasegawa, 2010). The sample of “B. chrysocomus” was collected at Kampong Simoro, Gunung Watu (01°15′45.8″S, 119°58′40.9″E), 559 m (K. Dewi, in litt., 2012), which lay in the northwestern portion of Lore Lindu not far south of Bakubakulu in Puro Valley, (01°07′S, 120°00′E), 600 m, where B. chrysocomus and B. andrewsi occur together (table 20). In this region, the two species are closely similar in physical size and color of fur, and the host specimens could be either B. chrysocomus or B. andrewsi. The other host sample, “B. prolatus,” does not reside in the Lore Lindu region and those specimens are likely misidentified B. chrysocomus (see my account of B. prolatus).

“Bunomys chrysocomus” and “Bunomys prolatus” from Lore Lindu have also been reported as hosts for the nematodes Subulura andersoni (Ascaridida, Subuluridae), Heterakis spumosa (Ascaridida, Ascarididae), and Syphacia muris ( =  S. rifaii, see Dewi and Hasegawa, 2010); “Bunomys chrysocomus” from Lore Lindu is host to Protospirura muris (Spirurida, Spiruridae) and Trichurus muris (Trichurida, Trichuridae); and “Bunomys prolatus” hosts Molinacuaria indonesiensis (Spirurida, Acuariidae) (Purwaningsih and Dewi, 2007). Again, Bunomys prolatus has been found only on Gunung Tambusisi at the western margin of the eastern peninsula and does not occur in Lore Lindu and I suspect the voucher specimens represent B. chrysocomus. The hosts identified as “Bunomys chrysocomus” are either B. chrysocomus or B. andrewsi, which in Lore Lindu are very similar in their external traits.

Finally, Dewi (2008, 2011) reported the nematodes Subulura andersoni, Heterakis spumosa, Syphacia rifaii, and Gongylonema neoplasticum (Spirurida, Gonglonematidae) were found in “Bunomys chrysocomus” collected at Pakuli, a village in the valley of Sungai Miu at 110 m (01°14′S, 119°56′E; see locality 7 in the gazetteer for Bunomys andrewsi). But 250 m is the lowest B. chrysocomus has been collected anyplace in Sulawesi where surveys for small mammals have been conducted (table 6), and 320 m is the lowest point in the valley of Sungai Miu where B. chrysocomus was encountered (see gazetteer for B. chrysocomus). The only accurately identified Bunomys from Pakuli represent B. andrewsi (see that account), and that may be the host species for the nematodes reported by Dewi.

Synonyms

Information about holotypes of the four taxa that are associated with Bunomys chrysocomus and reasons why the name attached to a particular holotype is a synonym is summarized below.

Rattus nigellus Miller and Hollister, 1921a: 72. HOLOTYPE: USNM 218140 (skin and skull; measurements are listed in table 18), an adult male collected November 8, 1916, by H.C. Raven (original number 2936). TYPE LOCALITY: Indonesia, Propinsi Sulawesi Tengah, Bumbarujaba (00°43′S, 120°04′E), 915 m (locality 5 in gazetteer and the map in fig. 22).

TABLE 18

Age, Sex, Weight (g), and External, Cranial, and Dental Measurements (mm) for Holotypes Associated with Bunomys chrysocomus, B. coelestis, B. prolatus, and B. torajae n. sp. (Unless otherwise indicated, I transcribed from skin tags the values for external measurements and measured the cranial and dental dimensions.)

Of the four names I synonymize with chrysocomus, two of them were proposed by Miller and Hollister. The first, Rattus nigellus, Miller and Hollister (1921a: 72) diagnosed as:

The authors remarked of nigellus that “this small species is related to R. adspersus rather than to R. chrysocomus of northern Celebes. It is easily distinguished from adspersus by its lesser external measurements; longer, softer pelage; and small skull.” Twelve specimens were identified as nigellus, 11 from Bumbarujaba, the type locality, and one from Labuan Sore. I located three additional examples of nigellus that Raven had trapped at Bumbarujaba (see locality 5 in the gazetteer); the individual from Labuan Sore (USNM 218138) is an example of what Miller and Hollister (1921a: 71) described, on a page preceeding their description of nigellus, as Rattus adspersus ( =  B. andrewsi; see that account).

I understand why Miller and Hollister thought the specimens from Bumbarujaba represented an undescribed species. The authors had never examined the holotype of chrysocomus and Raven did not encounter it in northern Sulawesi. He trapped 176 specimens of a Bunomys at Teteamoet, Kuala Prang, Gunung Klabat, and Temboan on the northeastern peninsula of the island (see the gazetteer for B. fratrorum and the map in fig. 50), which were subsequently identified by Miller and Hollister as B. chrysocomus. All, however, are examples of the larger-bodied B. fratrorum. Fur coloration and tail patterning as well as small size of skull and molars typical of the specimens from Bumbarujaba are strikingly unlike comparable traits in Raven's series from the northeast peninsula, which have somewhat paler fur, different tail patterns, and significantly greater external (compare the values in tables 19 and 41) as well as cranial and dental dimensions (table 42). And specimens in the sample from Bumbarujaba, although appreciably smaller in body size and cranial and dental dimensions than adspersus, as Miller and Hollister noted, closely resemble the larger-bodied adspersus in fur coloration and tail patterning. Without examples of true chrysocomus at hand for comparison, coupled with their misidentification of Raven's material from the northeast peninsula as chrysocomus, Miller and Hollister correctly noted that the specimens from Bumbarujaba were appreciably different not only from Raven's peninsular samples but from the central Sulawesian adspersus, and looked on them as representing an undescribed species.

TABLE 19

Descriptive Statistics for Measurements (mm) of Lengths of Head and Body, Tail, Hind Foot, and Weight (g), Derived from Samples of Bunomys chrysocomus, B. coelestis, B. prolatus, and B. torajae, n. sp. Mean ± 1 SD, observed range (in parentheses), and size of sample are provided. Mean values were used to compute LT/LHB. Specimens measured are listed in footnotes.

In their cranial and dental measurements and proportions, Miller and Hollister's sample of nigellus clusters with population samples from the northern peninsula, Gunung Tambusisi, and the southeastern peninsula (see Geographic Variation).

Rattus rallus Miller and Hollister, 1921a: 73. HOLOTYPE: USNM 219595 (skin and skull; measurements are listed in table 18), an adult female collected September 7, 1917, by H.C. Raven (original number 3233). TYPE LOCALITY: Indonesia, Propinsi Sulawesi Tengah, Gimpu (01°36′S, 119°53′E), 400 m (locality 35 in gazetteer and the map in fig. 22).

Rattus rallus, the second species to be named in the same publication as nigellus, was diagnosed by Miller and Hollister (1921a: 73–74) as:

Miller and Hollister assigned eight specimens to rallus: two from Gimpu, four from the valley of Danau Lindu, and two from Gunung Lehio. They overlooked an additional example collected by H.C. Raven from Gimpu that is represented by only a skull (see the gazetteer).

The holotype of rallus along with two additional specimens from Gimpu, the type locality, form one of the 10 population samples used in my multivariate analysis (table 2). In the scatter plots defined by first and second principal components and first and second canonical variates (upper and and lower graphs in figs. 26 and 27), scores representing the three specimens of rallus fall within or near the large cloud of points for specimens in the two population samples from along my transect in the west-central mountain block (Sungai Oha Kecil + Sungai Sadaunta and Danau Lindu + Gunung Kanino) and the animal from Bakubakulu just north of my transect. Scores for the seven specimens from Bumbarujaba, the type locality of nigellus, lay at the edge and to the left of the large west-central constellation. Among the variables influencing the position of the seven nigellus along the first canonical axis is their slightly higher braincase and larger bullae compared with the specimens of rallus from Gimpu (see Geographic Variation) and highlights two of the traits Miller and Hollister used to distinguish rallus from nigellus: “less arched braincase” and “smaller auditory bullae” (higher braincase and larger bullae in nigellus). Scores for nigellus from Bumbarujaba are more closely positioned near those for samples from the northern peninsula, Gunung Tambusisi at the western margin of the eastern peninsula, and Pegunungan Mekongga on the southeastern peninsula than to the points representing rallus from Gimpu, which is also reflected by the cluster configuration in the diagram of Mahalanobis distance as a phenetic measure of resemblance (fig. 28).

These multivariate analytical results described above pertain only to cranial and dental variables. The range of variation in fur coloration, color and pattern of the tail, ears, and feet, along with dimensions of the combined head and body, tail, and hind feet typical of the series of nigellus fall within that range of variation seen in the large sample obtained from my transect, which also embraces the range of variation in these external traits present among the three specimens of rallus. Miller and Hollister thought the smaller foot and more sharply bicolored tail of rallus distinguished it from nigellus, but neither trait is diagnostic. Length of hind foot varies within any large sample (table 19), and the extremes of a sharply bicolored tail and a monocolored tail connected by intermediate patterns is also usual in large samples (see the range of patterns enumerated in the description of B. chrysocomus).

There appears to be detectable geographic variation in cranial and dental variables among population samples of B. chrysocomus, which is reflected in the different spatial distribution of scores for the samples of nigellus and rallus in the discriminant-function ordinations, and the observations recorded by Miller and Hollister. The population samples defined here form two clusters, one from the west-central region, and the other from peninsulas east of there. Should analyses of DNA sequences and morphometric data from future samples demonstrate the populations living in the valleys and mountains in the west-central region to be genetically isolated from populations occurring elsewhere on Sulawesi, rallus would be the name to apply to the west-central form.

Rattus brevimolaris Tate and Archbold, 1935a: 7. HOLOTYPE: AMNH 101055 (skin and skull; measurements are listed in table 18), an adult female collected January 6, 1932, by G. Heinrich (original number 891). TYPE LOCALITY: Indonesia, Propinsi Sulawesi Tenggara (southeastern peninsula of Sulawesi), Lalolei (03°57′S, 122°03′E), 300 m (locality 38 in gazetteer and the map in fig. 22).

Tate and Archbold proposed the two other scientific names that turn out to be synonyms of B. chrysocomus, one as a species of Rattus, the other as a subspecies of Bunomys coelestis. Rattus brevimolaris was characterized by Tate and Archbold (1935a: 7) as “A rather small member of the chrysocomus group with somewhat thin pelage, a skull with small palatal foramina, narrowly pointed anteriorly and quite small molars.” The holotype was described as follows:

Tate and Archbold had never examined the holotype of Mus chrysocomus, but they correctly assessed the taxonomic affinities of brevimolaris (which Tate [1936: 554] repeated in his survey of “Some Muridae of the Indo-Australian Region”: brevimolaris “is intermediate in size and locality between inferior of the Mengkoka Mts. and andrewsi of Buton Island, southeast of Celebes. Its nearest relatives, however, on account of its small skull and teeth, should be sought in nigellus and rallus of Middle Celebes.”). Sody (1941: 317), who had actually examined the holotype of chrysocomus, noted that tail coloration was the only difference he could find between brevimolaris (known to Sody by the specimen listed in the gazetteer from locality 39 [Pulau Buton], the original description by Tate and Archbold, and two AMNH specimens from Lalolei that had been sent to Bogor [MZB 4074 and 4075, both with incomplete skulls]) and the holotype of chrysocomus. The tail of the latter is monocolor, those of brevimolaris bicolored; these extremes, however, are found within any large sample of B. chrysocomus collected from a single locality. The slightly higher braincase possessed by the holotype of brevimolaris, and the other two specimens from Lalolei (where the type was also collected), is one of several cranial variables that are responsible for clustering the scores representing the Lalolei specimens closely with those for the sample from Pegunungan Mekongga and more broadly with scores for the samples from the northeastern end of the northern peninsula, Bumbarujaba at the base of the northern peninsula, and Gunung Tambusisi at the western margin of the eastern peninsula as reflected in the ordination bounded by first and second canonical variates (fig. 27; see Geographic Variation).

Bunomys caelestis koka Tate and Archbold, 1935b: 1. HOLOTYPE: AMNH 101236 (skin and skull; measurements are listed in table 18), an adult female collected January 11, 1932, by G. Heinrich (original number 753). TYPE LOCALITY: Indonesia, Propinsi Sulawesi Tenggara (southeastern peninsula of Sulawesi), Pegunungan Mekongga (03°35′S, 121°15′E), Tanke Salokko, 1500 m (locality 37 in gazetteer and the map in fig. 22).

Tate and Archbold (1935b: 1) characterized “Bunomys caelestis koka” as “Smaller than true caelistis and with smaller hind foot, shorter claws, and shorter nasal bones … ,” and provided the following description:

The authors described and provided measurements for only the holotype; that specimen is one from a series of 21 collected by G. Heinrich from Pegunungan Mekongga (see locality 37 in the gazetteer).

The holotype and other specimens of koka do contrast with examples of Bunomys coelestis, which is known only by voucher samples from Gunung Lompobatang on the southwestern peninsula of Sulawesi (fig. 22), in the way that Tate and Archbold characterized koka. Those differences are part of the suite of phenetic external and and morphometric traits that distinguish examples of B. chrysocomus from specimens of B. coelestis (see Comparisons in the account of B. coelestis).

Coloration of the tail is an example of a chromatic trait linking koka with B. chrysocomus and not B. coelestis. Typically, specimens of B. coelestis have a sharply bicolored tail: from base to tip, the dorsal surface is dark brown and the ventral surface white (unpigmented). Dorsal surfaces of the tails are dark brown in the sample of koka, but the ventral surfaces range from all white (tail bicolored) to all brown (tail monocolored), and a range of brown speckling between those extremes, variation that is typical of the ventral tail pigmentation found in any large sample of B. chrysocomus.

Results of multivariate analyses of cranial and dental variables cement the identity of koka with B. chrysocomus rather than B. coelestis. In the discriminant-function analysis of population samples for B. chrysocomus, the points representing specimens of koka overlap those of the three scores for brevimolaris from the lowlands adjacent to the Mekongga highlands and nigellus from the southern tip of the northern peninsula (fig. 27). Furthermore, in a canonical variate ordination where the sample of B. coelestis from Gunung Lompobatang is compared with all 10 population samples of B. chrysocomus, the specimen scores for koka fall within the cluster of scores representing B. chrysocomus and well outside the cloud of points for B. coelestis (fig. 42). Clustering based on Mahalinobis distance (squared) also aligns the sample of koka (from Pegunungan Mekongga) with the rest of the population samples of B. chrysocomus, not with the sample of B. coelestis (figs. 21, 49).

Although originally described as a subspecies of B. coelestis, the specimens identified as koka from Pegunungan Mekongga are actually examples of B. chrysocomus and are phenetically more similar in their cranial and dental dimensions to brevimolaris of the nearby lowlands than to other geographic samples of B. chrysocomus.

Subfossils

Two right dentary fragments (fig. 33) and an isolated right lower incisor (tables 27, 28) were found in sediments excavated from Ulu Leang I, a cave in the Maros region on the coastal plain of the southwestern peninsula (locality 42 in the gazetteer and map in fig. 22; also mapped by Simons and Bulbeck, 2004: 168).

Fig. 33.

Subfossil right mandibular fragments of Bunomys chrysocomus from Ulu Leang I, a cave about 40 km northeast of Ujung Pandang in the Maros region near the tip of Sulawesi's southwestern peninsula (see gazetteer and the map in fig. 22). Upper set: partial dentary (×4) and accompanying molar row (×10) of AMNH 269954, an old adult. Lower set: comparable elements (×4) representing AMNH 266975, a young adult. Additional information is presented in the text and tables 27 and 28.

Excavations in the cave were described by Glover (1976), who provided me with 10,000–3500 years b.p. as the age of the dated sediments (Glover, in litt., 1989; Bulbeck, 2004, reported 9500–3470 years b.p.). More precise dates associated with the particular site (“Trench J”) at which the pieces were uncovered are unavailable.

Two other species of Bunomys occur on the southwestern peninsula: B. coelestis inhabits mountain forest on Gunung Lompobatang and B. andrewsi has been collected at lower elevations on the flank of the volcano and is represented in the lowlands by subfossils (see accounts of those species).

I compared the two jaw fragments with dentaries in samples of the three species. No modern samples of B. chrysocomus exist from the southwestern peninsula, so I first compared the subfossils with specimens of B. chrysocomus from the west-central region. Shape of the dentary fragments and sizes of the molars remaining in those pieces qualitatively and quantitatively closely resemble dentaries and molars in the sample of modern B. chrysocomus (table 28).

Bunomys coelestis is a close montane relative of B. chrysocomus, so my second set of comparisons set the subfossils against the sample of B. coelestis from Gunung Lompobatang to test the possibility that the subfossils actually represent a lowland sample of B. coelestis. In side-by-side comparisons of specimens of comparable age (judged by degree of molar wear), the fragmentary ramus of each subfossil is qualitatively more robust and the portion anterior to the first molar is shorter than the gracile B. coelistis with its more delicate ramus and elongate incisor sheath; the ramal remnants fit better with the morphology characteristic of B. chrysocomus.

Sizes of the molars associated with the fragments are more typical of the range of variation seen in B. chrysocomus than in B. coelestis (table 28). These qualitative observations of molar size were quantitatively verified by results from principal-components analyses that associate the subfossils with the sample of B. chrysosomus and not B. coelestis (fig. 34). In both ordinations containing specimen scores projected onto first and second principal components, size of molars is primarily responsible for the separation of scores for B. chrysocomus (right side of each graph) from the constellation representing B. coelestis with smaller molars (table 29).

Fig. 34.

Specimen scores representing Bunomys chrysocomus from Sungai Sadaunta (filled triangles; N  =  20), B. coelestis from Gunung Lompobatang (empty diamonds; N  =  20), and two subfossils from Ulu Leang I projected onto first and second principal components extracted from principal-components analysis of four dental log-transformed variables. Upper graph: AMNH 266975 is the subfossil (asterisk). Lower graph: AMNH 269954 is the subfossil (cross). Factor scores that denote subfossils fall within the huddle of specimen scores for B. chrysocomus and not those designating B. coelestis. See table 29 for correlations (loadings) of variables with extracted components and for percent variance explained.

The curvature of the subfossil incisor, the third subfossil fragment from Ulu Liang I, along with its width and shape of wear facet, matches examples of B. chrysocomus.

The two dentary fragments and lone incisor are not lowland samples of the montane B. coelestis.

Finally, I contrasted the two dentary fragments from Ulu Leang I with dentaries of B. andrewsi from Lombasang on the flanks of Gunung Lompobatang, and included the subfossil fragment of that species found in Batu Ejaya II. Compared with B. chrysocomus, examples of B. andrewsi are physically larger (see external measurements seen in tables 19 and 41, and cranial and dental measurements in table 42), and this size distinction is reflected in the dentaries. Bunomys andrewsi typically has more robust dentaries, a longer toothrow, and wider molars (tables 28, 42). Inspected side by side, the dentary fragments and molars from Ulu Liang I are smaller than those elements in the series of specimens from Lombasang, and this difference is quantitatively reinforced by results of principal-components analyses. Specimen scores projected on first and second axes (fig. 35) form two clusters along the first component, those for B. chrysocomus on the left and B. andrewsi on the right, a function of the larger molars in the latter (table 30).

Fig. 35.

Specimen scores representing Bunomys chrysocomus from Sungai Sadaunta (filled triangles; N  =  20), B. andrewsi from Lombasang (empty circles; N  =  18), two subfossils from Ulu Leang I, and one subfossil from Batu Ejaya II projected onto first and second principal components extracted from principal-components analysis of four dental log-transformed variables. Upper graph: AMNH 266975 is the subfossil (asterisk) from Ulu Leang I. Lower graph: AMNH 269954 is the other subfossil (cross) from Ulu Leang I. The subfossil from Batu Ejaya II (AMNH 265013) is represented in both scatter plots (hollow stars). Scores symbolizing the two subfossils from Ulu Leang I fall within the group of scores signifying B. chrysocomus and not B.andrewsi; the score for the subfossil from Batu Ejaya II is closely associated with the aggregation denoting B. andrewsi. See table 30 for correlations (loadings) of variables with extracted components and for percent variance explained.

The subfossil from Batu Ejaya II is associated with the aggregation of points representing the sample from Lombasang (B. andrewsi), and the two subfossils from Ulu Leang I nest with the cluster of scores denoting B. chrysocomus.

The three subfossil fragments from Ulu Liang I are the only representatives of B. chrysocomus found to date in lowlands of the southwestern peninsula. I would like to see more complete specimens but until any are encountered, either as fossils or members of living populations, my identification is a hypothesis, and one that is reasonable considering the morphology of the fragmentary remains and the known altitudinal distribution of B. chrysocomus elsewhere in Sulawesi. The species does occur in high mountain forests but has been more commonly encountered at intermediate and moderately low elevations. The montane forests on Gunung Lompobatang are inhabited by B. coelestis, which has not been collected below 1830 m (see gazetteer for B. coelestis). Bunomys andrewsi is the only other member of the genus recorded from lower altitudes in the southwestern peninsula, where it is represented by modern specimens at 1100 m on the flank of Gunung Lompobatang, and subfossils excavated from cave deposits in the lowlands (see account of that species).

The next account describes a strictly montane member of the Bunomys chrysocomus group, one found only on the high volcano Gunung Lompobatang at the southern end of the southwestern peninsula of Sulawesi.

Bunomys coelestis (Thomas, 1896)

Mus coelestis Thomas, 1896: 248.

Fourteen years after naming and describing Mus coelestis, Thomas (1910) used it as the type species for the genus Bunomys. In the years to follow, coelestis was shuttled between Bunomys and Rattus (table 4): it was retained in Bunomys by Tate (1936), later transfered to subgenus Rattus of Rattus (Ellerman, 1941, 1949; Laurie and Hill, 1954), placed in subgenus Bullimus of Rattus (Misonne, 1969), returned to Bunomys in the early 1980's (Musser, 1981b; Musser and Newcomb, 1983), and eventually renewed as a distinct species of Bunomys endemic to Gunung Lompobatang on the southwest peninsula of Sulawesi (Corbet and Hill, 1992; Musser, 1991; Musser and Holden, 1991; Musser and Carleton, 1993, 2005).

Holotype

BMNH 97.1.3.12, the skin and skull of an old adult female collected sometime during October, 1895, by A.H. Everett. Measurements (external, cranial, and dental) and other relevant data are listed in table 18. The skin, a conventional museum preparation, is intact and the pelage coloration is not noticeably altered. The cranium and mandible are whole, all incisors and molars are present.

Type Locality

“Piek van Bonthain” (the volcano, Gunung Lompobatang [see fig. 1], 05°20′S, 119°55′E), 6000 ft (1830 m; locality 1 in the gazetteer and map in fig. 22), southwestern arm of the island, Propinsi Sulawesi Selatan, Indonesia (cælestis means “belonging to heaven or of the sky/skies,” and presumably Thomas was referring to the high collection site on the flank of Gunung Lompobatang).

Emended Diagnosis

A montane member of Bunomys with long, dark brown fur that among species of Bunomys is morphologically most similar to B. chrysocomus, but is distinguished from it by the following traits: (1) longer head and body, tail, and hind feet, longer claws on the front feet; (2) darker brown upperparts, brownish gray underparts; (3) dorsal coat averages longer (18–22 mm; lowland samples of B. chrysocomus have a shorter coat [12–15 mm], those from middle elevations and mountains have slightly longer coats [15–20 mm]) with more of a woolly texture (smooth and silky in B. chrysocomus); (4) most specimens with a bicolor tail, brown over the dorsal surface and unpigmented ventral surface from base to tip (the range extends from monocolor brown through various degrees of ventral speckling and mottling to bicolored in B. chrysocomus), and all specimens in the sample lack white tail tips (of the 393 B. chrysocomus surveyed, 77 [20%] have a white tip); (5) average larger cranium with an appreciably longer rostrum, longer and narrower incisive foramen, longer diastema, wider zygomatic plate, and higher braincase; (6) more elongate dentary and longer, more slender lower incisors; (7) cranial and dental proportional distinctions that are mirrored in the scatter plots derived from multivariate analyses; (8) cusp t3 present on second upper molar in 89% of sample (only in 17% of sample of B. chrysocomus); (9) anterior labial cusplets absent from first lower molar of all specimens examined (present in half the sample of B. chrysocomus); and (10) anterior labial cusp typically present on second lower molar but infrequent on third lower molar (present in 25% of the sample; found in the third molars in 65% of the sample of B. chrysocomus).

Geographic and Elevational Distributions

All material of B. coelestis preserved in collections of museums was obtained at sites between 1800 and 2500 m on Gunung Lompobatang, and the species is likely restricted to montane rainforest formations there. Support for this supposition comes from collections made on the volcano in 1931 by G. Heinrich. He obtained 28 of the 30 documented specimens of B. coelestis in montane evergreen forest between 2000 and 2500 m. Heinrich also had a lower camp at Lombasang (05°16′S, 119°55′E), 1100 m, in the northwestern foothills of Gunung Lompobatang (see the maps in Heinrich, 1932, and Stresemann, 1940) where he trapped a large sample of B. andrewsi but no B. coelestis; Biror, which is near Lombasang, is the site of a more recent survey that yielded one example of B. andrewsi. Lowland tropical evergreen rainforest usually occurs at that elevation and constitutes the formation from which nearly all samples of B. andrewsi have been collected. Bunomys coelestis seems to be a montane species endemic to Gunung Lompobatang, the only highland massif with appreciable height on the southwestern peninsula of the island, but how low it once occurred will probably never be known. Except for steep slopes at 1000 m, former forest cover has been converted to farms and tree plantations below about 1700 m (Fraser and Henson, 1996), and the upper forested slopes of the volcano form an island “in a sea of densely-populated agricultural land east of Ujung Pandang” (Whitten et al., 1987: 519). The only lowland records of Bunomys from the southwestern peninsula consist of subfossil fragments I identify as B. andrewsi and B. chrysocomus (see those accounts) found in cave sediments near sea level. Except for the sites at Lombasang and Biror, no extant specimens of any species of Bunomys are known from altitudes between 1100 m and sea level, a zone now mostly deforested. Unless archaeological or fossil remains are discovered within this interval, the upper altitudinal limits of B. chrysocomus and the actual lower boundary of its close montane relative, B. coelestis will remain unclear.

Sympatry with Other Bunomys

No other species of Bunomys has ever been collected within the elevational range on Gunung Lompobatang in which B. coelestis is documented by specimens (table 4). Samples of B. chrysocomus and B. andrewsi come from lower elevations either on the volcano or elsewhere on the southwestern peninsula (see those two accounts of species).

Description

Here is Thomas's (1896: 248) original description of Mus coelestis:

Thomas aptly captured the essence of B. coelestis. It has a compact body, long muzzle, dark and thick fur, tail slightly shorter than the combined length of head and body, long front claws, and is one of the physically smaller species of Bunomys (LHB  =  147–179 mm, LT  =  136–165 mm, LHF  =  35–39 mm, LE  =  21–25 mm, ONL  =  37.6–41.8 mm), more similar in size to B. chrysocomus rather than the larger B. prolatus or B. torajae, n. sp. (table 19). The dorsal coat is very long (18–25 over the back), soft to the touch, and woolly in appearance. It is a rich dark brown highlighted by buffy speckling (produced by the combination of dark brown and buffy bands of the overhairs) over most of the head and body; sides of the body are slightly paler. Because guard hairs and overhairs are about the same length, the surface of the coat is smooth.

Fur covering the underparts of the head and body is also long (8–15) and soft. Dark grayish white pelage predominates in the sample, which characterizes 17 of the 27 adults in AMNH. Four have dark grayish-white coats tinged with buff (tips of the hairs are unpigmented or pale buff), and six express a rich buffy dark gray or ochraceous-gray ventral fur; the contrast between upperparts and underparts is evident but not sharply marked.

The ears (external pinnae) appear naked, but are scantily covered by short hairs. The dried ears on the stuffed museum skins are dark brown (I have not seen freshly caught animals).

Typically, the tail is slightly shorter than the combined length of head and body (LT/LHB  =  95%). Of the 30 specimens (adults and juveniles) stored in AMNH, 28 have sharply bicolored tails (as does the holotype): dorsal surface of the tail, from its base to its tip, is dark brown; the ventral surface, from base to tip, is unpigmented (white). In two specimens, the ventral surface is speckled brown (both scales and hairs are brown). None of the specimens exhibit a white tail tip.

Tarsal and metatarsal surfaces are typically brown and covered by unpigmented (silvery) hairs, all digits are white. The front claws are long and sharp, their lengths relative to lengths of the front digits exceeded only by the elongate claws of B. prolatus (fig. 36), and are not concealed by the short ungual tufts; comparable tufts of silvery hairs sparsely cover the hind claws. Palmar and plantar surfaces are typically unpigmented except for gray near the heel.

Fig. 36.

Views of right front foot in three species of Bunomys showing relative lengths of claws in adults. Upper: B. prolatus (MZB 12187, Gunung Tambusisi), longest claw  =  6.5 mm. Middle: B. coelestis (AMNH 101141, Gunung Lompobatang), longest claw  =  5.1 mm. Lower: B. chrysocomus (AMNH 265077, Gunung Tambusisi), longest claw  =  3.2 mm. Claw length in B. torajae, n. sp., is similar to that of B. chrysocomus.

Females exhibit the number of teats usual for all species of Bunomys (four, arranged in two inguinal pairs). Testes are likely large relative to body size, as in the close relative B. chrysocomus (table 9), but I have not seen fluid-preserved material to verify this possible proportion in B. coelestis.

Juveniles have soft and woolly dorsal pelage that is darker brown than the adult coat and slightly shorter (overhairs reach 18 mm). Underparts are dark grayish white. Coloration of the ears and feet match those of adults, and the tail is bicolored (dark brown on the dorsal surface, white along the ventral surface) and without a white tip.

The gracile skull is marked by a long rostrum, moderately wide interorbit, and deep braincase; each dentary is elongate, particularly that part of the ramus between incisor and first molar (figs. 37–Fig. 38.39). Molars are smaller relative to size of cranium and mandible than is typical of B. chrysocomus, but the basic occlusal patterns formed by cusp rows are similar in the two species (compare the occlusal views of molar rows from B. chrysocomus in fig. 12 with those of B. coelestis in fig. 40); the primary distinction between the two species lies in different frequencies of certain cusps and cusplets, as I describe below.

Fig. 37.

Dorsal views of adult skulls from four species of Bunomys. Upper pair, left to right: B. chrysocomus (AMNH 224719, Sungai Sadaunta) and B. coelestis (AMNH 101132, Gunung Lompobatang). Lower pair, left to right: B. prolatus (MZB 12190, holotype, Gunung Tambusisi) and B. torajae, n. sp. (MZB 34730, holotype). ×2.

Fig. 38.

Ventral views of the same skulls shown in figure 37. Upper pair, left to right: B. chrysocomus and B. coelestis. Lower pair, left to right: B. prolatus and B. torajae, n. sp. ×2.

Fig. 39.

Lateral views of the cranium and dentary from the same specimens presented in figures 37 and 38. Upper pair, left to right: B. chrysocomus and B. coelestis. Lower pair, left to right: B. prolatus and B. torajae, n. sp. ×2.

Fig. 40.

Occlusal views of right molar rows. Left pair: maxillary (left image; CLM1–3  =  5.9 mm) and mandibular (right image; clm1–3  =  6.1 mm) rows of Bunomys coelestis (AMNH 101151). Right pair: maxillary (left image; CLM1–3  =  6.6 mm) and mandibular (right image; clm1–3  =  6.7 mm) rows of Bunomys prolatus (AMNH 265075).

Karyotype

Not yet determined.

Comparisons

Among species of Bunomys, the montane B. coelestis is phenetically most similar to B. chrysocomus in traits associated with skins, skulls, and dentitions. While the two species bear a general resemblance to each other in body size and coat color, there are conspicuous differences between them. Compared with all samples of B. chrysocomus I examined, B. coelestis typically has a longer head and body, tail, and hind foot (table 19), and darker and longer fur (mean  =  20.1 mm, range  =  18–23 mm, for 23 adult B. coelestis; mean  =  15.5, range  =  13–18 mm in 41 adult B. chrysocomus from Sungai Sadaunta, 675 m). Bunomys coelestis has a darker brown dorsal coat that appears somewhat woolly in texture (dark brown with buff and gray highlights in B. chrysocomus, and sleek, silky fur), underparts are dark grayish brown (the range is grayish white to gray tinged or washed with pale or rich buff in most examples of B. chrysocomus). All individuals of B. coelestis lack a white tail tip (20% of the 396 B. chrysocomus surveyed exhibit a white tip; table 8); most have bicolored tails, brown along the dorsal surface, white ventrally from base to tip (in B. chrysocomus, tails range from bicolor to monocolor brown with intermediate patterns consisting of brown above and white below patterned by a range of mottling or speckling); and have appreciably longer claws on the four digits of each front foot than do specimens of B. chrysocomus (fig. 36).

Differences in absolute size and proportions of cranial and dental dimensions provide noticeable contrasts between B. coelestis and B. chrysocomus, which is evidenced by illustrations of skulls (figs 37–Fig. 38.39), univariate summary statistics (table 31), and results of multivariate analyses. Specimen scores projected on first and second principal components form two parallel elliptical clouds, one identifying specimens of B. chrysocomus, the other representing B. coelestis (fig. 42, upper graph). Axes of these clusters are phenetically distinct: their Y-intercepts are significantly different between the two species (−0.189 versus +2.746; F  =  10.94, P  =  0.001), but not their slopes (−0.279 versus −0.255; F  =  0.47, P  =  0.384). The spread of scores along the first axis is influenced by the positive and moderate to high loadings for cranial variables that highlight the overall larger skull of B. coelestis (indexed by occipitonasal length and zygomatic breadth); its longer facial skeleton (lengths of rostrum, diastema, incisive foramina, and bony palate) and postpalatal region; wider zygomatic plate, rostrum, bony palate, and incisive foramina; wider and deeper braincase, and larger bulla (r  =  0.24–0.86; table 32) compared with the bulk of specimens forming the sample of B. chrysocomus.

Dispersion of scores along the second axis and the moderate to high positive and negative correlations (table 32) point to the relatively higher braincase, longer diastema and incisive foramina, but more slender anterior cranial region of B. coelestis (indexed by breadths of rostrum, bony palate, mesopterygoid fossa, and incisive foramina), and weaker molars (shorter molar rows and narrower molars) compared to those variables in most examples of B. chrysocomus.

Specimen scores for samples of the two species projected on first and second canonical variates segregate into two discrete clusters along the first axis, a large one formed by combined population samples of B. chrysocomus, and a smaller group representing specimens of B. coelestis (fig. 42, lower graph). The dispersal is influenced by moderate to high negative correlations (r  =  −0.25 to −0.76; table 32) reflecting the generally larger skull and greater internal dimensions of B. coelestis (revealed also in univariate means; table 31) as compared with B. chrysocomus; covariation in lengths of diastema and incisive foramina, along with height of braincase, exerts the most force (table 32). In contrast, B. coelestis has a narrower incisive foramina and mesopterygoid fossa compared to B. chrysocomus.

The high positive loading on the second axis for breadth of zygomatic plate (r  =  0.74) and lesser negative values for lengths of bulla and molar row, and molar breadth (r  =  −0.43, −0.27, and −0.14, respectively) reflect the relatively wider plate of B. coelestis and its relatively smaller bullae and weaker molars compared to most specimens in the sample of B. chrysocomus.

In summary, B. coelestis has an overall larger cranium than B. chrysocomus, in which the rostrum is especially longer and thinner, the incisive foramina longer and narrower, the zygomatic plate wider, and the braincase higher. The mesopterygoid fossa and first upper molar are narrower, and bulla and molar row shorter relative to overall cranial size as compared with B. chrysocomus.

Results of UPGMA cluster analysis derived from Mahalanobis distances among centroids as a phenetic measure of resemblance also highlights the separation of B. coelestis from all population samples of B. chrysocomus (fig. 49).

Cranial contrasts between the two species are mirrored by mandibular distinctions (fig. 39). Compared with B. chrysocomus, the region between anterior margin of first molar and the incisor alveolus (diastema) is longer in B. coelestis and body of the ramus is not as high, resulting in a lower and more elongate structure. Bunomys coelestis also has appreciably longer and more slender lower incisors.

Occlusal patterns of molars are similar in B. chrysocomus and B. coelestis except for frequency of small cusps and cusplets found on certain molars. Nearly all specimens (25 of 28) in the sample of B. coelestis have a small cusp t3 on the second upper molar, but t3 is lost in most examples (164 of 197) of B. chrysocomus (table 10). Anterior labial cusplets could not be identified on first lower molars of any of the 24 specimens of B. coelestis surveyed, and occurred on the third lower molars only in 8 of the 24 examples. By contrast, first lower molars in about half of the sampled B. chrysocomus (62 of 120 specimens) exhibit anterior labial cusplets, and third lower molars in appreciably more than half of the sample (78 of 120) have such cusplets (table 11).

The morphological external, cranial, and dental configuration of B. coelestis is basically a slight but distinguishable modification of the anatomy seen in B. chrysocomus. Samples of the latter collected in montane forest habitats come from Gunung Kanino (1189–1555), Gunung Lehio (1880–2185 m), and Pegunungan Latimojong (2200 m) in the west-central mountain block; Gunung Tambusisi (1372–1830 m) at the western margin of the eastern peninsula; and Pegunungan Mekongga (2000 m) on the southeastern peninsula. Except for their long fur, none of these specimens exhibit the traits diagnostic of B. coelestis, and closely resemble the external, cranial, and dental features in samples of B. chrysocomus collected from lower elevations in the west-central region and southeastern peninsula (see account of B. chrysocomus).

Geographic Variation

There is no evidence that B. coelestis occurs anywhere else than above 1800 m on the forested slopes of Gunung Lompobatang, the high volcano that looms over the tip of the southwest peninsula (fig. 1). The specimens listed here constitute a single population sample of the species, and is large enough to be composed of age categories ranging from young to old adults. What intrasample variation I detected is expressed as differences in external, cranial and dental measurements reflecting age composition as well as individual differences among specimens of comparable ages. The extent of morphometric variation, for example, is indicated in summary statistics (table 31) and the generally tight cluster of specimen scores in the ordinations derived from principal-components and discriminant-function analyses (fig. 42).

Natural History

I lack firsthand experience with B. coelestis in its natural habitat, and field journals of collectors are devoid of useful ecological information. Long, thick, and dark fur, long claws on the forefeet, elongate rostrum and mandible, and protracted lower incisors, which are characteristic of B. coelestis, are traits associated with murine species living in cool and wet habitats of montane evergreen rain forests, at least in Sulawesi. Because in its morphology, B. coelestis appears to be a montane relative of B. chrysocomus, I suspect it to be terrestrial and have a similar diet—primarily earthworms, snails, arthropods, small vertebrates, along with some fruit. Its reproductive traits are also probably similar to those of B. chrysocomus. Results of extended fieldwork in patches of montane forest remaining on the volcano would test these suppositions.

Ectoparasites

Bunomys coelestis is parasitized by the tiny fur mite Listrophoroides (Marquesania) cucullatus (table 14), which is also found on Sulawesian Rattus hoffmanni and R. xanthurus as well as a variety of murines from the Indoaustralian region and Philippines (Bochkov and Fain, 2003: 577).

Synonyms

None.

A species so far known only from montane habitats on Gunung Tambusisi at the western end of the eastern peninsula is the subject of the following account.

Bunomys prolatus Musser, 1991

Bunomys prolatus Musser, 1991: 4.

Holotype

MZB 12190, the skin and skull of an adult male (original number 25) collected March 9, 1980, by C.H.S. Watts. External, cranial, and dental measurements, along with other data, are listed in table 18. Pieces are missing from both skin and skull; I have already described the extent of this damage (Musser, 1991: 4).

Type Locality

Gunung Tambusisi (“Tambusisi Ridge”) (01°38′S, 121°23′E), 6000 ft (1830 m; locality 1 in gazetteer and the map in fig. 22), near the western end of the eastern peninsula of the island, Propinsi Sulawesi Tengah, Indonesia (see fig. 1).

Emended Diagnosis

One of the largest in physical size among members of the Bunomys chrysocomus group (LHB  =  156–179 mm, ONL  =  40.4–43.2 mm) and further distinguished from members in that assemblage by the following combination of traits: (1) long, dense, and very soft fur; (2) tail that is much shorter than combined lengths of head and body (LT/LHB  =  79%), dorsal surface brown, ventral surface grayish brown, white, or white speckled with brown; (3) white tail tip typically absent (a 2 mm white tip present on one of seven specimens); (4) short hind foot relative to body size; (5) large, darkly pigmented epidermal scales on dorsal surfaces of fore- and hind feet as well as digits; (6) large and strong elongate claws with curved and sharp tips; (7) elongate cranium and mandible, long and tapered rostrum (with an associated long diastema and incisive foramina), wide interorbital region, and large braincase and auditory bulla; (8) narrow across zygomatic arches and narrow zygomatic plates; (9) long molar rows and wide molars; (10) cusp t3 absent from second and third upper molars; and (11) no anterolabial cusp on first lower molar and most specimens with anterolabial cusp on third molar.

Geographic and Elevational Distributions

The sample of B. prolatus was collected at 1830 m, an elevation that Whitten et al. (1987: 521) surmise is in the zone of upper montane forest on Gunung Tambusisi (“between 1700 and 2500 m”). Trapping efforts by members of the expedition did not extend higher. Presumably the species occurs in suitable habitat elsewhere on the mountain, possibly up to the summit (which is at 2422 m according to Whitten et al., 1987: 521). I suspect B. prolatus to be confined to montane evergreen rainforest formations—its actual altitudinal limits can be determined only by future survey.

Maryanto and Yani (2003) and Maryanto et al. (2009) have recorded B. prolatus from Lore Lindu National Park in central Sulawesi, which is certainly based on a misidentification (DNA has recently been extracted from a voucher specimen in Maryanto's Lore Lindu collection that was labeled “Bunomys prolatus,” but the DNA sequence identifies it as B. chrysocomus; Ken Aplin, personal commun., 2011). My transect was in what is now Lore Lindu National Park, and I never encountered the species, even during the months camped in montane forests on Gunung Kanino and Gunung Nokilalaki. Highland regions surveyed by other collectors outside but adjacent to the Park boundaries, and those sampled farther south in the west-central mountain block have never yielded B. prolatus; the species is recorded only from Gunung Tambusisi, which is at the western part of the eastern peninsula (fig. 1). Outside of Gunung Tambusisi, the places to expect B. prolatus are in the other highland regions of the eastern arm: Pegunungan Tokala to the east of Gunung Tambusisi; Gunung Katopasa to the north; and Pegunungan Balinggara (containing Gunung Bulutumpu) farther out on the peninsula (see the map in Whitten et al., 1987: 498). These mountains and stretches of highlands connecting them are high enough to support montane forest, and all, including Gunung Tambusis, are isolated from the expansive west-central mountain block in the central core of the island. Except on Gunung Lompobatang in the southwestern peninsula, and on the northern peninsula, B. penitus is the common Bunomys occurring in all montane forests surveyed outside of the eastern peninsular highlands. Bunomys prolatus may represent its ecological replacement on Gunung Tambusisi, as well as the other nearby mountain expanses; those highlands have yet to be surveyed for their small mammal faunas.

Sympatry with Other Bunomys

Bunomys prolatus and B. chrysocomus have been collected on the slopes of Gunung Tambusisi (see Musser, 1991, and tables 6, 20). The eight known specimens of B. prolatus were trapped on a ridge at 1830 m in upper montane forest. One B. chrysocomus was taken “just below the same ridge, at about the same altitude (6000 ft [1830 m]) but a few meters downslope, and on the same day (March 9) as were four examples of B. prolatus. Six specimens of B. chrysocomus were collected at 4500 [1372 m] and 4700 ft [1433 m] during the same period, March 6–27, 1980” (Musser, 1991: 6). C.H.S. Watts, the collector, wrote me (Musser, 1991: 40) that he “recalls catching the B. prolatus in traps set in short and very mossy forest along a ridgetop and the example of B. chrysocomus about 10 m below the ridge itself. He clearly remembers being impressed by the sharp and sudden vegetative transition between the ridgetop and just below it, and the concordant change in species of Bunomys.” Watts' samples of both species are small and whether the altitudinal ranges of each narrowly overlap or the two are truely altitudinally parapatric can only be determined by careful trapping efforts during future surveys.

TABLE 20

Summary of Elevational Relationships between Bunomys chrysocomus and Other Species of Bunomys Derived from Voucher Specimens

TABLE 21

Descriptive Statistics for Cranial and Dental Measurements (mm) Derived from Population Samples of Bunomys chrysocomus Mean ± 1 SD and observed range (in parentheses) are listed. Compare with statistics summarized in table 22.

TABLE 22

Descriptive Statistics for Cranial and Dental Measurements (mm) Derived from Population Samples of Bunomys chrysocomus from the West-Central Region^a Mean ± 1 SD and observed range (in parentheses) are listed. Compare with statistics summarized in table 21.

TABLE 23

Results of Principal Components Analysis of All Population Samples of B. chrysocomus Upper graph: correlations (loadings) of 16 cranial and two dental log-transformed variables are based on 232 specimens; includes all holotypes (Rattus nigellus, R. rallus, R. brevimolaris, and Bunomys coelestis koka) except Mus chrysocomus. Lower graph: correlations (loadings) of 12 cranial and two dental log-transformed variables are based on 233 specimens; includes the holotype of Mus chrysocomus (its skull is incomplete); see figure 26.

TABLE 24

Results of Discriminant-Function Analysis of All Population Samples of B. chrysocomus Upper graph: correlations (loadings) of 16 cranial and two dental log-transformed variables are based on 232 specimens; includes all holotypes (Rattus nigellus, R. rallus, R. brevimolaris, and Bunomys coelestis koka) except Mus chrysocomus. Lower graph: correlations (loadings) of 12 cranial and two dental log-transformed variables are based on 233 specimens; includes the holotype of Mus chrysocomus (its skull is incomplete); see figure 27.

TABLE 25

Selected Examples of Microhabitats at Trap Sites in Which Some of the Specimens of Bunomys chryscomus Were Collected on My Transect in Central Sulawesi, 1973–1974 Descriptions of the collection sites are summarized from my field journals (in Mammalogy Archives at AMNH). See habitats in figures 29–Fig. 30.Fig. 31.32.

TABLE 25

(Continued)

TABLE 25

(Continued)

Description

Bunomys prolatus is the largest in physical size among species in the B. chrysocomus group (LHB  =  156–179 mm, LT  =  125–142 mm, LHF  =  33–35 mm. LE  =  24–26 mm, ONL  =  40.4–43.2 mm), has a protracted face between eyes and nose, short tail and hind feet relative to combined lengths of head and body (LT/LHB  =  79%, LHF/LHB  =  20%), and brownish-gray fur that is long, soft, and dense. The elongate skull and mandible are portrayed in figures 37–Fig. 38.39, and occlusal patterns of the molars in figure 40. I have elsewhere provided a full description of the skin, skull, and dentition of the species (Musser, 1991).

The Latin prolatus means “elongate” and is an appropriate name for this species of Bunomys characterized by its elongate face, skull, and front claws.

Karyotype

No information.

Comparisons

Among species of Bunomys, B. prolatus is morphologically (and phenetically) most similar to B. chrysocomus, B. coelestis, and B. torajae, n. sp. Here I compare B. prolatus with the first two species; contrasts between B. prolatus and B. torajae, n. sp., will be presented in the following account where that new species is described. Bunomys prolatus will be compared with certain population samples of B. andrewsi and B. penitus—members of the B. fratrorum group—in each of those respective accounts.

Bunomys prolatus and B. chrysocomus: Elsewhere I detailed contrasts and similarities between the two species (Musser, 1991), and here will only summarize major differences. Compared with samples of B. chrysocomus from throughout its documented geographic range (see the map in fig. 22), the sample of B. prolatus averages larger in body size (indicated by combined length of head and body), has shorter hind feet and tail (absolutely and relative to length of head and body; table 19), longer pelage, strikingly more robust and longer claws on the forefeet (fig. 36), and more extensive brown epidermal scutellation on dorsal surfaces of feet and digits.

Differences in absolute size and proportions summarize the primary morphometric cranial and dental contrasts between the two species: B. prolatus has a larger skull and molars and differs in proportions of internal cranial dimensions. The contrast is evident in the cranial illustrations of B. prolatus and B. chrysocomus (figs. 37–Fig. 38.39), univariate descriptive statistics (table 31), and the ordination of specimen scores for samples of B. prolatus and B. chrysocomus projected on first and second principal components (fig. 43). Size is the primary factor dispersing the spread of scores along the first axis with scores for B. prolatus and the larger specimens of B. chrysocomus falling in the right half of the scatter plot; positive and moderate to high loadings for nearly all variables are responsible for this distribution (r  =  0.19–0.81; table 33). Univariate means of most measurements are greater in the sample of B. prolatus than in samples of B. chrysocomus (table 31). The isolation of the B. prolatus cluster along the second axis (shape factor) underscores its relatively wider interorbit; larger braincase; and longer rostrum, diastema, bony palate, incisive foramina, bullar capsule, and molar row compared with B. chrysocomus (table 33). Also predominant in isolating the scores for B. prolatus at the top of the scatter plot is its relatively narrower skull (breadth across the zygomatic arches) and rostrum compared with the conformation in B. chrysocomus, its relatively much narrower zygomatic plate, and relatively slightly narrower bony palate, mesopterygoid fossa, and incisive foramina; univariate mean values for these measurements are similar in the two species, indicating that the dimensions are relatively smaller in B. prolatus compared with B. chrysocomus. This quantification reinforces the visual contrast between the two species when skulls are compared side by side: B. prolatus has larger molars than B. chrysocomus, a cranium that is about as wide (except for interorbit and braincase) but significantly longer—protracted by comparison with the skull of B. chrysocomus—with a relatively narrower zygomatic plate, rostrum, and bony palate (figs. 37–Fig. 38.39).

The primary mandibular difference between the two species mirrors the cranial contrasts. Bunomys prolatus has longer dentaries, particularly in the more elongate bony stretch between incisor alveolus and anterior margin of the molar row (fig. 39).

Frequency of some cusps and cusplets differ. A cusp t3 is not present on any example of Bunomys prolatus, but is part of the occlusal surface on the second molar in 17% of the B. chrysocomus sample, and on the third molar in 5% of the sample (table 10). All specimens of B. prolatus lack an anterior labial cuspet on the first lower molar; such a cusp occurs in 52% of the sample of B. chrysocomus (table 11).

Bunomys prolatus and B. coelestis: These two species have been collected only from montane forest habitats. Both have dark, soft, and long fur, long front claws (fig. 36), a large cranium with an elongate rostrum, and long and gracile mandible (figs. 37–Fig. 38.39). Bunomys prolatus is larger than B. coelestis, as indexed by its average longer head and body, hind foot, and ears, but has a shorter tail (absolutely relative to length of head and body; LT/LHB  =  79% for B. prolatus, 95% for B. coelestis). The Tambusisi rat has larger, longer, and more robust claws on digits of the front feet (fig. 36) as well as more extensive brown epidermal scutellation on dorsal surfaces of the feet and digits.

Bunomys prolatus has a larger skull than B. coelestis, as indicated by the greater size of most of its cranial and dental dimensions; however, a few other cranial variables are of lesser magnitude than comparable dimensions in B. coelestis (table 31). These two sets of contrasts are quantitatively summarized through principal-components analysis. Specimen scores for B. coelestis and B. prolatus projected onto first and second principal components form two widely separated clusters along the first axis (fig. 43). Their positions are determined primarily by the large and positive loadings for skull length; breadths of interorbit and braincase; lengths of rostrum, bony palate, bullar capsule; and size of molars (r  =  0.57–0.77; table 33). Compared with B. coelestis, the Tambusisi species has a longer skull, wider interorbital region and braincase, longer rostrum and bony palate, larger bullar capsule, and heavier molars. The negative loadings associated with the first principal component points to the less-flared zygomatic arches (narrower zygomatic breadth) of B. prolatus compared with B. coelestis, along with its shallower braincase, much narrower zygomatic plate, and shorter diastema (the counterpoint to the longer bony palate and molar rows in B. prolatus). These dimensional contrasts between the two species are reflected in univariate means for the variables (table 31) and can be visually appreciated in the illustrations of skulls (figs. 37–Fig. 38.39).

Frequency of particular cusps and cusplets differ. Cusp t3 is absent from second and third upper molars of all examples of B. prolatus, but in B. coelestis is present on the second upper in 89% of the sample and on the third molar in 5% (table 10). An anterolabial cusp is present on the third lower molar in 75% of the B. prolatus sample but only in 25% of the sample of B. coelestis (table 11).

Geographic Variation

Because all the specimens of B. prolatus were taken in one trapline at a single locality, I cannot assess variation associated with geography. The differences in coat color among the specimens I have already described (Musser, 1991) and the range in measurements for each variable reflect individual variation and variation attributable to age among the adult specimens. Age-related size differences among crania, ranging from old adult (the largest) to adult and finally young adult (the smallest) individuals, is illustrated elsewhere (Musser, 1991: 20).

Natural History

All information concerning B. prolatus comes from the collector, C.H.S. Watts (in litt., 1980). The specimens were trapped on a ridgetop at 1830 m in forest where the trees were short (4 m) and gnarled, and on exposed areas the vegetation was heathlike. Pitcher plants (Nepheris) abounded and the ground was deeply covered in moss. On Gunung Tambusisi, 1830 m is in the zone of upper montane forest (Whitten et al., 1987: 521). One individual was caught in deep moss during the day between 10 and 11 a.m.; all the others were taken during the night.

A female had one recent placental scar.

The external morphology of B. prolatus is that of a terrestrial rat. Its long muzzle, very long and strong claws, and overall skull conformation suggests a diet consisting primarily of invertebrates, likely containing a range of items similar to those eaten by B. chrysocomus (see that account and table 13).

Ectoparasites

Bunomys prolatus is host to the flea Sigmactenus alticola pilosus (table 14), and that ectoparasite has also been recorded from 14 other species of endemic Sulawesi murine rodents (Bunomys penitus, B. chrysocomus, and B. karokophilus, n. sp.; Margaretamys elegans; Maxomys hellwaldii, M. wattsi, and Maxomys sp.; Melasmothrix naso and Tateomys rhinogradoides; Paruromys dominator; Taeromys celebensis and Taeromys sp.; Rattus hoffmanni and R. facetus [recorded as R. marmosurus]) and the nonnative Rattus exulans (Durden and Beaucournu, 2000).

The nematode, Syphacia rifaii (Oxyuroidea, Oxyuridae), was extracted from host specimens identified as B. prolatus that were collected in Lore Lindu (Dewi and Hasegawa, 2010), but the host rats are likely examples of B. chrysocomus and not B. prolatus.

Synonyms

None.

The next account also deals with another montane isolate, one phenetically closely allied with Bunomys prolatus but occurring far to the south of Gunung Tambusisi in the high mountainous landscape of the Quarles Range in the southern part of the west-central mountain block. The species is named and described here by the four authors listed and they should be cited as the authorities for the name.

Bunomys torajae, new species, G.G. Musser, A.S. Achmadi, J.A. Esslestyn, and K.C. Rowe

Holotype

MZB 34730, the skin, skull, fluid-preserved carcass, and tissue for extraction of DNA of an adult male (original number KCR 1294) collected October 26, 2011, by A.S. Achmadi and K.C. Rowe. Standard external measurements, weight, and other data, and measurements of the skull and dentition are listed in table 18. The stuffed skin is complete, the cranium and mandible are intact (figs. 37–Fig. 38.39).

Type Locality

Tropical lower montane rain forest at 2600 m (trapline GD01, −2.84467° S, 119.38295° E) near Gunung Gandangdewata (−2.748253° S, 119.368536° E for the peak, Rano Rano, Kampung Rantepangko, desai Tondok Bakaru, Kabatuan Mamasa), which is the highest peak in Pegunungan Quarles in the southern portion of the west-central mountain block of the island's core, Kabupaten Mamasa, Propinsi Sulawesi Barat, Indonesia. The trapping area is on a large plateau and some distance from the peak.

Diagnosis

On average, in physical size the largest member of the B. chrysocomus group (LHB  =  156–210 mm, W  =  98–128 g, ONL  =  41.2–41.8 mm) and further characterized by the following combination of traits: (1) a protracted muzzle and large external pinnae; (2) dorsal fur luxuriant, soft, long, somewhat woolly in appearance, and dark brown speckled with buff, ventral fur also soft and thick and buffy dark gray; (3) dorsal carpal and metacarpal surfaces brown, digits and claws unpigmented, front claws slender but short and delicate relative to body size, hind foot short in relation to head and body length; (4) tail averages slightly shorter than length of head and body (LT/LHB  =  93%), dark brownish gray on dorsal surface, white or lightly mottled grayish brown over ventral surface; (5) white tail tip characterizing half the specimens in sample, short to moderately long relative to length of tail (mean  =  7.0%, range  =  2%–11%); (6) testes moderately small in relation to length of head and body; (7) moderately large cranium with a long, wide, and tapered rostrum (with an associated long diastema); (8) wide and smooth interorbital region; (9) gracile and weakly flaring zygomatic arches; (10) large braincase, moderately small auditory bulla, narrow zygomatic plates, long and wide bony palate, short and wide incisive foramina; (11) an elongate dentary, especially that section of the ramus between molar row and edge of incisor alveolus; (12) long molar rows and wide molars; and (13) cusp t3 absent from second molar in half the sample, absent from third upper molars in entire sample.

Referred Specimens

Total 7 with the holotype; MZB 34730–35, 34904. All were collected during the interval, October 26 to November 3, 2011.

Geographic and Elevational Distributions

The only known sample of Bunomys torajae consists of the specimens collected in tropical lower montane forest at 2500 and 2600 m on Gunung Gandangdewata in the Quarles Range, part of the southern highlands of the west-central mountain block (see gazetteer and the map in fig. 22). No specimens exist in older collections stored in the world's museums.

No present evidence indicates the range of B. torajae to extend beyond the western mountainous region of central Sulawesi and outside the high elevations in the Mamasa area. None of the collections of Bunomys from other west-central mountains sampled (Gunung Nokilalaki, Gunung Lehio, Rano Rano, Gunung Latimojong, Gunung Balease) contain examples of B. torajae. Whether the new species is endemic to Pegunungan Quarles or occurs at high elevations elsewhere in the west-central mountain block will have to be determined by results of additional surveys of the many currently unexplored montane habitats in the core of Sulawesi.

Sympatry with Other Bunomys

Bunomys torajae is regionally sympatric with three other species of Bunomys in the Mamasa highlands. A single specimen (BMNH 21.2.9.12) documents the presence of B. chrysocomus. It was obtained by the Dutch “Controleur” on May 19, 1916, with the provenance noted as “Mamasa, Toradjalander.” On the back of the tag attached to the skin is written “Rattus chrysocomus Hoffm.” in Oldfield Thomas's handwriting. The skin is misshapen and the fur discolored; only an anterior segment of the rostrum and a piece of the mandible remains of the skull. Breadth across both upper incisor tips is 1.9 mm, which is within the range of measurements from a sample of 22 B. chrysocomus that Musser collected along the Sungai Sadaunta (mean  =  1.8 mm, range  = 1.7–2.1 mm); each of the three skulls of B. torajae measure 2.0 mm. Ranges for the six specimens of B. andrewsi (2.0–2.5 mm) and four examples of B. penitus (2.2–2.3 mm) collected by Achmadi and Rowe from Gunung Gandangdewata are typical for those two species, which have larger skulls and teeth (for example, the range is 2.0–2.3 mm for 27 B. andrewsi from Kuala Navusu and Pinedapa and 2.1–2.6 mm for B. penitus from several places in the west-central mountain block). There are no recent records of B. chrysocomus from the Mamasa area and its distribution there remains unknown.

Of the other two Bunomys from the Mamasa district, B. andrewsi has been obtained near Sumarorong, south of Mamasa at 970 m, near Lambanan and Mambulillin at about 1500 m, northeast of Mamasa, and Gunung Gandangdewata at 1600 m, north of Mamasa (see gazetteer). Samples of B. penitus come from near Lambanan and at 2000 m on Gunung Gandangdewata. On the latter highland, Achmadi and Rowe collected B. torajae (2500–2600 m), B. penitus (about 2000 m), and B. andrewsi (1600 m) during the period, October 26-November 11, 2011; the distribution of the three species as indicated by samples at hand reflects local sympatry but not syntopy.

Etymology

Gunung Gandangdewata is part of the southern mountains in central Sulawesi known in Bahassa Indonesia as Tana Toraja, land of the indigenous Toraja people. “Belonging to” is one of the meanings of the Latin feminine genitive case ending -ae and by combining it with Toraja we signify that Bunomys torajae belongs to Tana Toraja. The scientific name will always identify Tana Toraja as the place where B. torajae was first discovered should future surveys find the species elsewhere in the west-central mountain block.

Description

(based primarily on four adult skins and three skulls) in body size, Bunomys torajae is the largest of the species in the B. chrysocomus group (LHB  =  156–175 mm, LT  =  160–170 mm, LHF  =  36–39 mm, LE  =  26–28 mm, W  =  98–128 g, ONL  =  41.2–41.8 mm), with dark-brown upperparts, buffy dark-gray underparts, and a moderately long tail. Soft, dense, and long (coat 20–25 mm) to the touch, and somewhat woolly to the eye, fur covering the upperparts is dark brown from muzzle to rump with buff and black speckling (produced by the combination of dark gray underfur, overhairs that are dark gray for most of their lengths with subterminal and terminal buffy or black bands, all intermixed with black guard hairs); sides of the body are slightly paler, brown rather than dark brown. Because the guard hairs are only slightly longer than the overhairs, the surface of the coat is smooth. Fur over the forearms and legs is the same color as the sides of the body, and the muzzle, cheeks, and around the eyes match the dark brown of the back.

Fur covering the underparts of the head and body is also soft and thick, but shorter (10–15 mm thick) than the dorsal fur, which is usual in murids. Underparts of three of the four skins at hand are covered with buffy dark gray fur from the chest to inguinal region (hairs are dark gray for most of their lengths and end in long bright buffy tips); throats are dark gray. One specimen is paler, the background is dark gray, but the wash is pale buff. The contrast between dorsal and ventral coats is inconspicuous.

The large dark brown ears (pinnae) appear to be naked, but are scantily covered by short hairs.

The tail is nearly equal to or shorter than the combined length of head and body (LT/LHB  =  93%). Tail patterning is individually variable: dorsal surface and sides are dark brownish gray in all four rats; the ventral surface is white from base to tip in three specimens and white mottled with grayish brown in the fourth. Two specimens show a distal white segment (unpigmented on all surfaces) ranging from 2% to 11% of the tail length (mean  =  7.0%; table 8). The rat with the longer white tip also has a sharply bicolored tail throughout its length, the overall pattern similar to that common to B. penitus (see that account).

Metacarpal and metatarsal surfaces range from gray to brownish gray (the integument is white but densely covered with unpigmented and brown hairs), with silvery highlights in some specimens. Palmar pads are gray, the rest of the palmar surface ranges from pale gray to unpigmented; all the plantar surface ranges from gray to dark gray. Digits of front and hind feet are typically unpigmented. All claws are unpigmented, those on the front digits are moderately long and sharp and not concealed by ungual tufts, but comparable tufts of silvery hairs cover and extend beyond the hind claws. Size of the claws in relation to body size is closely similar to the proportion seen in B. chrysocomus (see fig. 36).

Females exhibit the number of teats usual for all species of Bunomys (four, arranged in two inguinal pairs). Testes are relatively small in relation to length of head and body (table 9).

The specimens available are in adult pelage; the juvenile coat will have to be described after examples of that age group are collected. However, the fur is probably similar to that in juveniles of other species of Bunomys: dense, woolly, and very dark gray upperparts with a flat tone (lacking the glossy sheen of the adult fur); dark grayish white or buffy gray underparts.

In size and shape, the skull of B. torajae is similar to that of B. prolatus (figs. 37–Fig. 38.39; table 31). Smooth sides of the long and tapered rostrum are interrupted by slight bulges of the nasolacrimal capsules. Frontal bones forming the dorsal surface of the broad interorbit are slightly inflated into two low mounds. Dorsolateral margins of the interorbit are smooth, without ridging, but postorbital edges are outlined by slight ridges that extend back along dorsolateral margins of the domed braincase but not all the way to the lamboidal ridges. The occiput, as in other species of Bunomys, is moderately deep and mostly roofed by the interparietal. The short and wide incisive foramina end well anterior to front surfaces of the first molars (with a correspondingly long bony palate), and each zygomatic plate is narrow with its concave anterior margin projecting beyond the dorsal zygomatic root. The ectotympanic bullae are small relative to skull size.

Configuration of each dentary resembles the shape of this element in other members of the B. chrysocomus group, particularly B. prolatus (fig. 39). Elongate and gracile describe the configuration. Musser's (1991: 15) original description of the dentary of B. prolatus could stand in for that element in B. torajae.

Enamel layers of the narrow upper and lower incisors are pigmented orange, the lowers paler than the uppers. Uppers emerge from the rostrum at either a 90° angle to the ventral surface of the rostrum (orthodont configuration) or curve back (opisthodont). The lower incisors have narrow sharp tips and elongate wear facets.

Size and occlusal topography of maxillary and mandibular molars are similar in B. torajae and B. prolatus (figs. 40, 41; table 31). Long molar rows and wide molars characterize both species. Cusp patterns forming the occlusal surfaces are unelaborate and after even moderate use the cusp rows wear to irregular basins surrounded by dentine. The lack of occlusal complexity and the cusp morphology that contributes to it as is portrayed in the original description of B. prolatus (Musser, 1991: 17) also fits the cusp patterns possessed by B. torajae. Presence or absence of most accessory cusps cannot be determined for B. torajae, especially on the mandibular molars, because the teeth are too worn in the three specimens at hand. Of the two rats in which the uppers are not excessively worn, cusp t3 is present on the second molar in one individual but absent in the other, and the comparable cusp is absent from the third molar in both specimens (table 10).

Fig. 41.

Occlusal views of right maxillary (left image; CLM1–3  =  6.5 mm) and mandibular (right image; clm1–3  =  6.7 mm) molar rows of Bunomys torajae, n. sp. (MZB 34733).

Karyotype

No information.

Comparisons

Bunomys torajae requires comparison with two sets of species. The first comprises B. prolatus, B. coelestis, and B. chrysocomus, the three phenetically (but not necessarily genetically) most closely allied to the Gandangdewata rat (see cluster diagrams in figs. 21 and 49). Bunomys andrewsi and B. penitus constitute the second set; both are sympatric with B. torajae on Gunung Gandangdewata and all three appear superficially similar in their external characteristics. The sample of B. torajae used in the analyses is small (three adults) so outcome of the following comparisons should be tested in the future with more examples of that species.

Bunomys torajae and B. prolatus: Of all the described species of Bunomys, B. torajae is phenetically most similar to B. prolatus. Both occupy isolated montane habitats and resemble one another in physical body size, most cranial and dental dimensions, and overall conformation of skulls and dentitions. Both species have luxuriant, soft, and thick brown fur covering the upperparts and dark gray underparts washed with buff, except that the buffy suffusion is more intense in B. torajae.

Although similar in some external traits, they do differ in others. Bunomys torajae averages greater in lengths of head and body, tail, hind feet, and ears, but the most spectacular difference is relative length of tail. Not only does B. torajae have an absolutely much longer tail than B. prolatus (see below) but it is also longer relative to length of head and body (LT/LHB  =  93% in B. torajae versus 79% for B. prolatus). Relative to length of head and body, lengths of feet and ears are not dissimilar in the two species—those dimensions scale to body size, averaging larger in B. torajae, which also averages greater in head and body length (table 19). The front claws of B. torajae are moderately long with slender tips and their size relative to body size is similar to the proportions seen in B. chrysocomus (see fig. 36); they diverge sharply from the strikingly more robust and appreciably longer claws on the forefeet of B. prolatus (fig. 36) that are huge in relation to body size as compared with the shorter and gracile configuration in B. torajae. The Gandangdewata species also lacks the extensive brown epidermal scutellation on dorsal surfaces of feet and digits that is so characteristic of B. prolatus (Musser, 1991).

Size differences of appendages is graphically portrayed in the ordination of specimen scores for samples of B. torajae and B. prolatus projected onto first and second principal components where the scores form two discrete clumps along the first axis, those on the right signal the larger B. torajae, those on the left B. prolatus (fig. 44, upper graph). Correlations for lengths of tail and hind foot (r  =  0.97 and 0.91, respectively; table 34) are the most influential in spreading the scores along the first component and these variables show the greatest univariate mean differences between the two species (LT  =  165.3 mm, LHF  =  37.6 mm for B. torajae; 132.4 mm and 33.9 mm, respectively, for B. prolatus).

Both species are generally similar in overall conformation of their skulls along with the magnitude of many cranial and dental measurements (figs. 37–Fig. 38.39; table 31). The notable morphometric distinctions are displayed in a scatter plot where specimen scores for B. torajae and B. prolatus are projected onto first and second principal components (fig. 44, lower graph). The spread of scores along the first axis is primarily influenced by the positive and large loadings for several cranial variables that distinguish the two species (r  =  0.67–0.98; table 34). Compared with B. prolatus, the Gandangdewata species has more flaring zygomatic arches and a wider rostrum, bony palate, mesopterygoid fossa, and incisive foramina; B. torajae also has a shallower braincase (r  =  −0.69). These contrasts are reflected in univariate descriptive statistics (table 31) and images of skulls (figs. 37–Fig. 38.39).

Noteworthy among the loadings on the second component is that for bullar length (r  =  0.82; table 34), reflecting B. torajae's much smaller bullae compared with B. prolatus.

Coronal patterns of the primary cusps on molars are closely similar in the two species (figs. 41, 42) as is length of the molar row (mean is 6.5 mm for each sample). Similarities or differences between the two species in presence or absence of accessory cusps and cusplets cannot be reliably assessed because the sample of B. torajae is small and the molars too worn.

Fig. 42.

Upper graph: Specimen scores representing the sample of Bunomys coelestis (empty diamonds; N  =  18) and all population samples of B. chrysocomus (filled triangles; N  =  232) projected onto first and second principal components extracted from principal-components analysis of 16 cranial and two dental log-transformed variables. Arrows point to scores for holotypes of Bunomys coelestis (empty diamond) and Bunomys caelestis koka (empty triangle). Ellipses outline 95% confidence limits for cluster centroids. Equations for the regression lines are: B. chrysocomus, Y  =  −0.279× −0.189 (F  =  24.10, P  =  < 0.000); B. coelestis, Y  =  −0.479× +2.746 (F  =  4.74, P  =  0.045). Lower graph: Scores for the same samples of B. coelestis (empty diamonds) and B. chrysocomus (empty triangles) projected onto first and second canonical variates extracted from discriminant-function analysis of the 16 cranial and two dental log-transformed variables. Included are scores for the holotype of Bunomys coelestis (filled diamond marked by arrow) and sample of Bunomys caelestis koka (filled triangle, arrow identifies holotype). Scores for the specimens of koka, including the holotype, mostly nest within the polygon bounding scores for B. chrysocomus and nowhere near the cluster marking B. coelestis. See table 32 for correlations (loadings) of variables with extracted components or canonical variates and for percent variance explained for both ordinations.

Fig. 43.

Specimen scores representing Bunomys prolatus (asterisks; N  =  8), all population samples of B. chrysocomus (filled triangles; N  =  232), and B. coelestis (empty diamonds; N  =  18) projected onto first and second principal components extracted from principal-components analysis of 16 cranial and two dental log-transformed variables. Upper graph: B. prolatus compared with B. chrysocomus. Lower graph: B. prolatus contrasted with B. coelestis. Correlations (loadings) of variables with extracted components and percent variance explained for both scatter plots are listed in table 33.

Fig. 44.

Specimen scores representing samples of Bunomys torajae (empty squares) and B. prolatus (asterisks) projected onto first and second principal components extracted from principal-components analysis. Upper graph: derived from log-transformed values for lengths of head and body, tail, hind foot, and ear (N  =  3 B. torajae, 6 B. prolatus). Lower graph: based on log-transformed values for 14 cranial and 2 dental variables (N  =  3 B. torajae, 8 B. prolatus). See table 34 for correlations (loadings) of variables with extracted components and for percent variance explained for both scatter plots.

Bunomys torajae and B. coelestis: These two species need to be compared because both have been collected only from southern montane forest habitats, their dorsal coat is dark brown, soft, and thick, and both have a large cranium with a long and narrow rostrum and an elongate and gracile mandible (figs. 37–Fig. 38.39) with slender and sharp lower incisors.

Bunomys torajae is physically larger than B. coelestis, as indexed by its average longer head and body, tail, hind feet, and ears (table 19). However, tail length relative to length of head and body is similar (LT/LHB  =  93% for B. torajae, 95% for B. coelestis) as is pelage length (up to 25 mm long for the dorsal coat, 10–15 mm for the ventral fur). While color of the dorsal fur is similar in the two species, there is a difference in the range of chromatic expression of the ventral coat. Most specimens of B. coelestis have dark grayish-white underparts, a few show a pale or dense buffy wash (see that account); all four skins of B. torajae have buffy dark gray ventral coats (whether these four skins represent the usual coloration or the range is similar to that seen in B. coelestis will have to be determined from a larger sample of B. torajae). Finally the front claws of B. torajae are shorter than the elongate claws typical of B. coelestis, their shape and bulk relative to body size similar to the proportion in B. chrysocomus rather than B. coelestis (see fig. 36).

The ordination of specimen scores for samples of B. torajae and B. coelestis projected onto first and second principal components (fig. 45, upper graph) summarizes difference in size of external variables between the two species. Positive moderate to high loadings for all four variables sort the scores into two marginally overlapping clumps along the first axis, the larger-bodied B. torajae on the right, and the physically smaller B. coelestis to the left, with loadings for lengths of head and body, tail and ear (r  =  0.88, 0.80, and 0.65, respectively; table 35) the most forceful in scattering the scores. These three variables show the greatest univariate mean differences between the two species (table 19).

Fig. 45.

Specimen scores representing samples of Bunomys torajae (empty squares) and B. coelestis (filled diamonds) projected onto first and second principal components extracted from principal-components analysis. Upper graph: derived from log-transformed values for lengths of head and body, tail, hind foot, and ear (N  =  3 B. torajae, 20 B. coelestis). Lower graph: based on log-transformed values for 14 cranial and 2 dental variables (N  =  3 B. torajae, 18 B. coelestis). See table 35 for correlations (loadings) of variables with extracted components and for percent variance explained for both ordinations.

Bunomys torajae has a larger skull and much heavier molars than B. coelestis, along with some greater internal measurements (table 31); a few other cranial variables are of lesser magnitude than comparable dimensions in B. coelestis, and there is essentially no significant difference between the two samples in postpalatal length and length of bulla. These sets of dimensional contrasts and similarities are summarized by specimen scores for B. torajae and B. coelestis projected onto first and second principal components where they form two widely separated clusters along the first axis (fig. 45, lower graph), the scatter determined primarily by the large and positive correlations (r  =  0.49–0.90; table 35) for most cranial and dental dimensions. Compared with B. coelestis, the Gandangdewata species has a wider interorbital region and braincase, longer and wider rostrum, longer and wider bony palate, wider mesopterygoid fossa and incisive foramina, and heavier molars. The high negative loadings associated with the first principal component (r  =  −0.57, −0.61, and −0.72) points to B. torajae's shallower braincase, much narrower zygomatic plate, and notably shorter incisive foramina compared with these variables in B. coelestis. These differences between the two species are reflected by univariate means (table 31) and in the images of skulls (figs. 37–Fig. 38.39).

Occlusal patterns of primary molar cusps are similar in the two species (figs. 41, 42). The sample of B. torajae is too small and the molars too worn to detect potential similarities or differences in presence or absence of accessory cusps and cusplets.

Bunomys torajae and B. chrysocomus: With its long muzzle and fur color, B. torajae conveys the physical impression of a high-mountain population of B. chrysocomus, which it is not, and the reason behind documenting here the specific integrity of the Gandangdewata rat relative to the more widespread B. chrysocomus. Compared with samples of B. chrysocomus from throughout its documented geographic range (see the map in fig. 22), the sample of B. torajae contains much larger rats that have greater average lengths of head and body size, tail, hind feet, and ears as well as mass (table 19); length of tail relative to length of head and body in B. torajae (LT/LHB  =  93%) falls wihin the range derived from the samples of B. chrysocomus (84%–98%). The size disparity in external variables is visualized in the ordination of specimen scores for samples of B. torajae and B. chrysocomus projected onto first and second principal components (fig. 46, upper graph; here the scores for B. chrysocomus are represented by a sample collected and measured by Musser from Sungai Sadaunta, Tomado, and Sungai Tokararu—univariate statistics are tabulated in table 68). The larger external variables in B. torajae as indicated by the moderate to large and positive loadings (r  =  0.37–0.94; table 36) separate the three scores for that species to the right of the cluster signifying B. chrysocomus along the first component.

Fig. 46.

Specimen scores representing samples of Bunomys torajae (empty squares) and B. chrysocomus (filled triangles) projected onto first and second principal components extracted from principal-components analysis. Upper graph: derived from log-transformed values for lengths of head and body, tail, hind foot, and ear (N  =  3 for B. torajae; N  =  71 for B. chrysocomus from Sungai Sadaunta, Tomado, and Sungai Tokararu). Lower graph: based on log-transformed values for 14 cranial and 2 dental variables (N  =  3 B. torajae; N  =  232 for all 10 population samples of B. chrysocomus). See table 36 for correlations (loadings) of variables with extracted components and for percent variance explained for both ordinations.

In addition to the dimensional dissimilarities noted above, B. torajae has a thicker coat than specimens in samples of B. chrysocomus, even those from high elevations (see that account), and smaller testes relative to length of head and body (table 9). Range of size of the front claws is similar in the two species, but because B. torajae is physically larger its claws are relatively smaller.

Absolute size and proportions summarize the primary morphometric cranial and dental contrasts between the two species: B. torajae has a larger skull and molars and differs in proportions of internal cranial dimensions. The contrast is evident in the cranial illustrations of B. torajae and B. chrysocomus (figs. 37–Fig. 38.39), univariate descriptive statistics (table 31), and the ordination of specimen scores for samples of B. torajae and all 10 population samples of B. chrysocomus projected onto first and second principal components (fig. 46, lower graph; all population samples of B. chrysocomus are employed—the pattern of scores is similar when B. torajae is compared with only samples of B. chrysocomus from the west-central mountain block, which is not illustrated here). Size is the primary factor affecting the spread of scores along the first axis with those indicating B. torajae and the larger specimens of B. chrysocomus falling in the right half of the scatter plot. Significant covariation among all variables, as indicated by the moderate to large positive loadings (r  =  0.25–0.73), influences the spread of points—especially forceful is zygomatic breadth, length and breadth of rostrum, length of diastema, and breadths of bony palate and mesopterygoid fossa (table 36); univariate means of most cranial and dental measurements are greater in the smaller sample of B. torajae than in the much larger sample of B. chrysocomus (table 31). The isolation of scores denoting B. torajae from those signifying B. chrysocomus along the second axis underscores the relatively wider interorbit of B. torajae, its longer rostrum, larger braincase, narrower zygomatic plate, longer diastema and bony palate, more spacious incisive foramina, and heavier molars compared with B. chrysocomus (see the correlations in table 36). The relatively narrower zygomatic plate of B. torajae is most forceful (r  =  −0.80) in isolating the scores for B. torajae at the top of the scatter plot. These results from the principal-components analysis reinforce the visual contrast between the two species when skulls are compared side by side: B. torajae typically has larger molars than B. chrysocomus, and a larger skull with a relatively much narrower zygomatic plate (figs. 37–Fig. 38.39).

The primary mandibular difference between the two species mirrors the cranial contrasts. Bunomys torajae has longer dentaries, particularly in the more elongate stretch between incisor alveolus and anterior margin of the molar row (fig. 39).

Occlusal patterns of primary molar cusps are similar in the two species (figs. 41, 42), but the molars too worn in the sample of B. torajae to detect potential similarities or differences between B. torajae and B. chrysocomus in presence or absence of accessory cusps and cusplets.

Bunomys torajae, B. andrewsi, and B. penitus: Comparisons here are between the few examples of B. torajae and samples of B. andrewsi and B. penitus from localities in the west-central mountain block, which include specimens from Gunung Gandangdewata where B. torajae and the other two species are sympatric but elevationally discrete (specimens of B. torajae comes from 2500 and 2600 m, those of B. penitus from 2000 m, and the sample of B. andrewsi from 1600 m).

In snare or trap, in hand, and as study skins, examples of the three species from Gunung Gandangdewata appear to the collector nearly indistinguishable from one another in external traits—adults of B. torajae and B. andrewsi are especially difficult to separate. Bunomys torajae is larger but not heavier; it typically has a longer head and body, tail, hind foot, and ear than B. andrewsi (tables 19, 41), but length of tail relative to length of head and body is similar (93% versus 92%) and mass is not so different (116.8 g versus 111.7 g). Both species have soft and long, dark brown dorsal coats and buffy dark gray underparts, but the coat appears woolly in texture and is slightly longer in B. torajae (dorsal coat up to 25 mm in B. torajae, up to 20 mm in B. andrewsi). The dorsal coat of B. andrewsi has stronger yellow and buff highlights because the speckling appears more intense due to the longer buffy tips; B. torajae shows a denser dark brown—a subtle but noticeable difference. Finally, patterning of the tail differs. Tails of B. andrewsi are typically monocolor brown with some specimens showing a mottled underside but usually so intensely mottled that it appears monocolored. Tails of B. torajae are bicolored: brown on the upper surface and either white or only slightly mottled with gray or pale brown along the underside.

Bunomys torajae is similar to B. penitus in length of head and body (comparing adults of comparable age), but B. torajae has, on average, a shorter tail and hind foot than B. penitus, and lesser mass (tables 19, 41). Mean length of ear is about the same (26.8 mm versus 26.0 mm), which indicates the ears to be larger relative to body size in B. torajae. Tail length in relation to length of head and body also differs with B. torajae possessing a relatively shorter tail (LT/LHB  =  93% versus 102%). Both species have soft and dense fur, but compared with B. torajae the dorsal coat of B. penitus is more intensely flecked with buff (the pigmented hair tips are longer), the guard hairs extend farther beyond the overhair layer (inconspicuous in B. torajae), and the underparts are grayish white (buffy dark gray in B. torajae). Bunomys penitus typically has a bicolored tail, brownish gray along the dorsal surface and white along the entire ventral surface; a white tip is usual (table 8). Tail pattern in three of the B. torajae is similar to that seen in B. penitus, but the fourth specimen is lightly mottled with gray along the underside of the tail; a white tail tip occurs less frequently than in B. penitus.

Differences in magnitudes of cranial and dental dimensions between B. torajae and B. andrewsi and between the former and B. penitus are documented by univariate means (table 37) and images of skulls (fig. 48).

Bunomys torajae has a longer but narrower skull (as indexed by occipitonasal length and zygomatic breadth) than B. andrewsi; overall it is less robust and more gracile in conformation, but some of its internal dimensions are greater, others lesser. For example, B. torajae has a wider interorbit, longer but narrower rostrum, shallower braincase, longer diastema, and longer and wider bony palate, but notably narrower zygomatic plates and mesopterygoid fossa, much shorter incisive foramina, smaller bullae, and shorter molar rows. Proportional (shape) distinctions between B. torajae and B. andrewsi are summarized by specimen scores designating each species projected onto first and second principal components (fig. 47, upper graph). Along the second component, the scores form two discrete clusters, the spread influenced by several cranial variables (table 38): Bunomys torajae has a relatively wider interorbital region, longer rostrum and diastema, more expansive bony palate (r  =  0.33–0.84), and appreciably shorter incisive foramina (r  =  −0.55) compared with B. andrewsi.

Fig. 47.

Specimen scores representing samples of Bunomys torajae (empty squares) compared with samples of B. andrewsi (empty circles) and B. penitus (filled inverted triangles) from the west-central mountain block projected onto first and second principal components extracted from principal-components analysis of log-transformed values for 14 cranial and 2 dental variables. Upper graph: B. torajae (N  =  3) contrasted with B. andrewsi (N  =  40; filled circles  =  scores for six specimens from Gunung Gandangdewata). Lower graph: the same specimens of B. torajae compared with B. penitus (N  =  170; empty inverted triangles  =  scores of four specimens from Gunung Gandangdewata). See table 38 for correlations (loadings) of variables with extracted components and for percent variance explained for both ordinations.

Bunomys torajae has a smaller skull than B. penitus, and nearly all of its cranial and dental dimensions are less (as indicated by univariate means). The exceptions are breadths of the interorbit and bony palate, which exceed, on average, those dimensions in the sample of B. penitus. This size disparity among the variables is reflected by the specimen scores representing each species projected onto first and second principal components (fig. 47, lower graph). The distribution of scores along the first axis, signifying variation in size, is influenced by nearly all variables as denoted by the moderate to high positive loadings listed in table 37 (r  =  0.25–0.75), and explains the position of the three scores for B. torajae that lay to the left (smaller) of most scores representing the larger B. penitus (and without overlapping the scores signifying the four Gandangdewata B. penitus). Along the second axis, scores for B. torajae and B. penitus form two separate clusters, revealing noteworthy proportional contrasts. Compared with B. penitus, the Gandangdewata species has a relatively wider interorbit, shallower braincase, longer diastema, wider bony palate, narrower mesopterygoid fossa, shorter incisive foramina, smaller bullae, and smaller molars (see the positive and negative loadings in table 38).

Assuming that specimens of comparable age are compared, the gracile skull of B. torajae with its small molars is at once distinguished from the robust skull of B. andrewsi and larger skull of B. penitus with its heavier molars, whether specimens of the latter two species are from Gunung Gandangdewata or elsewhere in the west-central mountain block (fig. 48).

Fig. 48.

Dorsal (top) and ventral (bottom) views of adult skulls representing three species of Bunomys collected on Gunung Gandangdewata. Left to right: B. andrewsi (MZB 34917, 1600 m), B. torajae (MZB 34730, holotype, 2600 m), and B. penitus (MZB 34850, 2000 m). ×2.

Geographic Variation

Because all the samples of B.torajae come from a single locality, color and morphometric variation associated with geography will have to wait for additional material if the species proves to occur in montane forests beyond the Mamasa region.

Natural History

Examples of Bunomys torajae were caught on the ground and during the night in montane forest at 2500 and 2600 m. Fourteen other murids were collected at those elevations during the same survey: Tateomys rhinogradoides and T. macrocercus, Melasmothrix naso, Sommeromys macrorhinos, Margaretamys elegans and M. parvus, Haeromys sp., Taeromys sp., Paruromys dominator, Eropeplus canus, Eropeplus-like new genus and species, Maxomys musschenbroekii, and Rattus hoffmanni and R. facetus.

Litter size is unknown, but one or two young is usual for the species of Bunomys for which that kind of information is available—B. torajae is probably no different.

Like B. prolatus, the external morphology of B. torajae is that of a terrestrial rat. Its long muzzle, sharp lower incisors, and overall skull conformation suggests a diet consisting primarily of invertebrates, likely containing a range of items similar to those eaten by B. chrysocomus and even B. andrewsi; also, a partially mycophagous diet cannot be ruled out (see those accounts and table 13).

Ectoparasites, Pseudoscorpions, and Endoparasites

No records.

Synonyms

None.

Holotype

BMNH 97.1.2.28, the skin and skull of a young adult female collected October 8, 1895, by C. Hose and E. Hose. Measurements (external, cranial, and dental), along with other information, are listed in table 40. The skin is stuffed in the conventional museum fashion and shows no significant alteration in color of fur. The cranium and mandible are intact, and all incisors and molars are present.

Type Locality

Rurukan (01°21′N, 124 52′E), 3500 ft (1068 m; locality 7 in gazetteer and on the map in fig. 50), northeastern tip of the northern peninsula of Sulawesi, Propinsi Sulawesi Utara, Indonesia.

Emended Diagnosis

One of the larger-bodied members of the B. fratrorum group (LHB  =  157–190 mm, WT  =  175 g, ONL  =  41.5–46.5 mm) and further set apart by the following combination of traits: (1) dorsal fur brownish gray speckled with buff, ventral coat grayish white tinged with pale buff; (2) tail typically equal to combined length of head and body (99%–101%), brown on dorsal surface, white or mottled brown on ventral surface, most with a white or speckled tip (86% of the 99 specimens surveyed) that is moderately long relative to tail length (mean  =  18.0%, range  =  4%–75%); (3) testes small relative to body size (8%); (4) sperm head short, asymmetrical and gently curved in outline, with a short tail attached near the middle of its concave surface; (5) cranium and mandible robust (6) rostrum and zygomatic plate wide, interorbit narrow, braincase deep, postpalatal region (basicranium) short, and ectotympanic bulla small relative to size of cranium; (7) molar row relatively long; (8) cusp t3 absent from second and third upper molars in most of sample (89% and 91%, respectively); (9) anterolabial cusp rare on second lower molars (12%) and absent from third lower molars; and (10) posterior labial cusplet present on first lower molar in about half of sample and on third lower molar in three-fourths of sample.

Geographic and Elevational Distributions

Bunomys fratrorum is endemic to the northeastern section of the northern peninsula where it is documented by voucher specimens collected at localities scattered from Teteamoet, near the tip of the peninsula, west to near Gunung Mogogonipa (see the map in fig. 50). This region is on the peninsular mainland east of Gorontalo (00°31′N, 123°03′E) where the distribution of B. fratrorum is concordant with that of several other mammals: the macaques Macaca nigra and M. nigrescens (Fooden, 1969; Groves, 1980, 2005); and the murids, Echiothrix leucurus, Taeromys taerae, Rattus xanthurus, and R. marmosurus (Musser and Carleton, 2005; also see table 81). Bunomys fratrorum has not been collected from islands adjacent to the Sulawesi mainland.

Known elevational range extends from lowlands near sea level (Teteamoet, for example) to about 2000 m on Gunung Klabat (table 5).

Sympatry with Other Bunomys

Bunomys fratrorum is the only member of the B. fratrorum group found on the northern arm east of the Gorontalo region. There it is sympatric with B. chrysocomus, which also occurs elsewhere on Sulawesi (see that account and table 6). C.H.S. Watts collected examples of both species 1 km north of Gunung Mogogonipa at 250 m during August 2–8, 1985 (table 20). Bunomys fratrorum and B. chrysocomus are the only species in the genus recorded from the northeastern tip of the northern peninsula east of the Gorontalo region.

Description

As is usual in his descriptions of new taxa, Thomas (1896: 246) captured the essence of Mus fratrorum:

After providing measurements, Thomas noted (1896: 247) that besides “the type, there are several other specimens from Rurukan, two from Menado, and one from Mount Masarang. This species is apparently most closely allied to M. chrysocomus, Hoffm., also a native of Celebes, but differs from it by its larger size, beaded supraorbital edges, and much heavier molars.” Apparently Thomas's perception of the close morphological relationship between fratrorum and chrysocomus prompted him to propose “fratrorum,” which is derived from the Latin frater meaning “brother.”

Thomas knew the characteristics of chrysocomus, at least as reflected in the type specimen, because during a tour of several European museums in the late 1800s, he examined the holotype of chrysocomus at Dresden during October, 1887, and recorded his observations and measurements in a journal, which is in the library of the mammal section at BMNH (a photographic copy was made by G.H.H. Tate in 1937 and is stored in the Mammalogy Archives at AMNH). It was clear to Thomas that fratrorum was a species distinct from chrysocomus and that both occurred on the northeastern region of the northern peninsula of Sulawesi.

The large-bodied B. fratrorum (LHB  =  157–190 mm, LT  =  150–200 mm, LHF  =  36–44 mm; ONL  =  41.5–46.5 mm) has soft, long (12–15 mm long), and glistening brownish-gray dorsal fur brightly speckled with buff (“finely sprinkled with dull yellowish,” as Thomas wrote). In a large sample, the tonal range extends from brownish gray to a dark brownish gray with blackish highlights. Fur covering the underparts is dark gray and either speckled with buff (Thomas's “dirty greyish yellow”), which is usual, or heavily washed with buffy tones. Ears are brownish gray, rubbery in texture (noted in a fluid-preserved example), their inner and outer surfaces covered with short, fine hairs.

Dark brown above, white or speckled below, and around the tip is the basic coloration of the relatively long tail, which is typically as long as the head and body in most samples (LT/LHB  =  99%–101%). Most specimens (86% of the 99 specimens surveyed) exhibit a white or speckled tip that is moderately long (mean  =  18.0%, range  =  4%–75% of tail length in 85 specimens; table 8). Color pattern varies in any large sample. The dorsal surface and sides of the tail are brown in all specimens, the ventral surface is either glistening white the entire tail length or lightly to heavily speckled with tan; the tail tip is either white or speckled to some degree. Thirty-three males and females from Temboan (locality 17) illustrate the variation. The dorsal surface and sides of the tail range from brown to dark brown, the ventral surface is white in 16 specimens and lightly to heavily speckled in the other 17; 31 have a whitish tip that is entirely white in 25 rats, but speckled in six.

Dorsal surfaces of front and hind feet are white and covered with short, fine silvery hairs (some specimens are brown from grease stains). Claws are short and unpigmented, and not concealed by the meager silvery ungual tufts. Palmar and plantar surfaces are naked and gray.

Females possess four teats configured in two inguinal pairs. Males have small testes relative to body size (8%; see table 9). Gross morphology and ultrastructural anatomy of the spermatozoa are described by Breed (2004).

Bunomys fratrorum has a large skull, its overall dimensions matched only by B. penitus, with a moderately long and narrow rostrum and a wide zygomatic plate (figs. 52–Fig. 53.54; tables 42, 45). The interorbit is narrow and its dorsolateral margins framed by moderately high ridges, the braincase wide and deep, the incisive foramina short and wide, and the bullae small. Each dentary is robust and similar in shape to those of the other species in the B. fratrorum group.

Fig. 52.

Dorsal views of adult skulls from species of Bunomys. Left to right: B. fratrorum (USNM 217650, Temboan, northeastern peninsula); B. andrewsi (AMNH 225652, Kuala Navusu, central Sulawesi), and B. penitus (AMNH 225275, Gunung Kanino, west-central mountain block). ×2.

Fig. 53.

Ventral views of the same skulls shown in figure 52. From left to right: B. fratrorum, B. andrewsi, and B. penitus. ×2.

Fig. 54.

Lateral views of the cranium and dentary of the same specimens presented in figures 52 and 53. Upper pair: B. fratrorum and B. andrewsi. Lower image: B. penitus. ×2.

Large molars with simple occlusal patterns are typical of B. fratrorum (fig. 12). Contributing to this simplicity is the absence of cusp t3 from the second and third upper molars in 89%–91% of the sample (table 10). As in most other species of Bunomys, an anterior labial cusplet is absent from the first lower molar, but a posterior labial cusplet typically forms part of the chewing surface on the first lower molar in about half of the sample and on the third lower molar in 78% of the sample (fig. 12; table 11). An anterolabial cusp is absent from the second lower molar in most specimens (present on only 12 of 58 individuals) and was not detected on any third lower molar.

Karyotype

No information.

Comparisons

Bunomys fratrorum first requires comparison with B. chrysocomus. The two species occur sympatrically on the northern peninsula east of Gorontalo, and fratrorum for a while was regarded as a synonym of B. chrysocomus (Ellerman, 1949; Laurie and Hill, 1954; table 4).

Demonstrating that B. fratrorum is not just a geographic population of one of the members of the large-bodied B. fratrorum group found on Sulawesi south of the northern peninsula demands its contrast with B. penitus, B. andrewsi, and B. karokophilus, n. sp. Here I will contrast the characteristics of B. fratrorum first with B. chrysocomus, then with B. andrewsi followed by B. penitus. Comparisons between B. fratrorum and B. karokophilus, n. sp., will be entertained in the account in which the new species is described.

Bunomys fratrorum and B. chrysocomus: In the years between 1896 and 1941, fratrorum was recorded in the scientific literature by most taxonomists as a distinct species and first placed in Mus (Trouessart, 1897: 485; Matschie, 1900: 286), then either Rattus (Tate, 1936: 551; Ellerman, 1941: 190) or Frateromys (Sody, 1941: 316).

Two reports during this period provided different allocations of fratrorum. Meyer (1899: 24) listed Mus fratrorum, as well as Mus chrysocomus, as synonyms of Mus callitrichus, and Miller and Hollister (1921a: 72) “included” fratrorum in “Rattus chrysocomus.” The reasoning behind Meyer's action is explained in the first paragraph of his account of “Mus callitrichus” (Meyer, 1899: 24; translated from the German by E.M. Brothers; the German text is reproduced in appendix 2):

I borrowed eight specimens that Meyer had identified as “Mus callitrichus,” which are stored in the Staatliches Naturhistorische Sammlungen Dresden, Museum für Tierkunde. Two are from Rurukan (locality 7 in the gazetteer) and were part of Thomas's original series of fratrorum; the rest were collected at Lota (locality 4 in the gazetteer). All are examples of Bunomys fratrorum. Meyer was able to contrast the holotype of chrysocomus with specimens that Thomas had identified as fratrorum, but the distinctive size differences in cranial and dental dimensions between specimens in the two samples that had stimulated Thomas to name the larger animal as a new species (remember that Thomas had also studied the holotype of chrysocomus) were interpreted by Meyer as the kind of differences related to age and sex found in a sample of a single species. Furthermore, Meyer considered chrysocomus and fratrorum to be synonyms of Jentink's (1879) Mus callitrichus.

Meyer had accepted Jentink's identification of the four specimens sent to him (presumably four of the examples identified here as fratrorum). Jentink compared Meyer's material with the type series of Mus callitrichus, which was stored in the museum at Leiden, and found no noteworthy differences. This is not surprising. The original types associated with M. callitrichus consisted of 12 specimens and represented not one species but five: three specimens of Taeromys callitrichus, one example of Paruromys dominator, three specimens of Bunomys chrysocomus, four Bunomys fratrorum, and a single example of Rattus hoffmanni (Musser, 1970). To Jentink, the characteristics of Meyer's specimens fit within the range of variation exhibited by the type material of M. callitrichus.

In 1921, Thomas (1921: 111) rebutted Meyer's (1899) synonymy: “In his large paper on the mammals of Celebes … Dr. A.B. Meyer has placed both chrysocomus and fratrorum as synonyms of R. callitrichus, Jent., but all these are perfectly distinct differing considerably in size and having quite appreciable diagnostic skull characters.” The statement was quoted 20 years later by Sody (1941: 316), who also noted that “This certainly is correct (as I was able to control when studying the type of Mus chrysocomus at the Dresden Museum).” In addition to Thomas (1896) and Meyer (1899), Sody was the only other researcher who had actually studied the holotype of Mus chrysocomus, contrasted it with examples of fratrorum, and published their observations.

In the same year that Thomas (1921) reasserted the distinctness of fratrorum as compared with chrysocomus, Miller and Hollister (1921a) “included” (their word) fratrorum within chrysocomus, but did not explain why. I suspect their view derived from study of the mammals collected in northeastern Sulawesi by H.C. Raven during the early 1900s. Raven obtained large samples of a species from Teteamoet, Kuala Prang, Gunung Klabat, and Temboan (localities 1, 5, 6, and 14 in the gazetteer and on the map in fig. 50) that were idenfitifed by Miller and Hollister as “Rattus chrysocomus.” These are the only examples of a species in what has been called the Rattus chrysocomus group (see Tate, 1936, for example, and table 4), now recognized as Bunomys, that were collected by Raven during his survey in northeastern Sulawesi. Neither Miller nor Hollister had ever seen an actual chrysocomus from the northeastern end of the northern peninsula. At the time none were present in collections of museums in the United States, and the species was represented only by specimens collected during the late 1800s in institutions outside that country: the holotype in Dresden (Hoffmann, 1887) and three of the 12 specimens at Leiden that had been designated cotypes of Mus callitrichus by Jentink in 1879 (Musser, 1970). It would not be until 1985 that chrysocomus would again be encountered by collectors from northeastern Sulawesi (at two sites in Bogani Nani Wartabone National Park, localities 3 and 4 in gazetteer for Bunomys chrysocomus and on the map in fig. 22). Because Raven obtained only one kind of Bunomys in the northeastern peninsula, a species which seemed to be common, Miller and Hollister apparently assumed it was chrysocomus (the older name) and the same animal that Thomas had described as Mus fratrorum. Thomas's description of fratrorum does match all of Raven's specimens, and most external, cranial, and dental dimensions of the holotype of fratrorum, but not the holotype of chrysocomus, fall within the range of variation shown by Raven's samples (tables 19, 40–TABLE 4142). Raven had collected examples of the large-bodied fratrorum and surprisingly had not encountered the smaller-bodied chrysocomus.

Influential checklists published after 1941, and originating primarily from the Natural History Museum in London, treated fratrorum as a synonym of Rattus chrysocomus (Ellerman, 1947: 265, 1949: 52; Laurie and Hill, 1954: 118). But by 1970 its separate status as a distinct species, and reaffirmation of Thomas's observations, was promulgated by Musser (1970, 1981b, 1991), Musser and Newcomb (1983: 393), Musser and Holden (1991: 406), and accepted by Corbet and Hill (1991, 1992) in their world list of mammalian species and systematic review of Indomalayan mammals, and cemented in place by Musser and Carleton (1993: 582; 2005: 1300).

Bunomys fratrorum and B. chrysocomus are easily distinguished by body size alone and that this dimensional contrast could be interpreted as variation within a single species as Meyer did is remarkable. Bunomys fratrorum is physically larger than B. chrysocomus with longer head and body, tail, and hind foot (values for B. chrysocomus in table 19 and those for B. fratrorum in table 41). The tail in B. fratrorum is about equal to length of head and body (LT/LHB  =  99%–101%), while B. chrysocomus has a relatively shorter tail (LT/LHB  =  84%–98%). Color pattern of the tails also differ. In both species, tails are brown or brownish gray over their dorsal surfaces. Tails end in a moderately long white tip relative to tail length (mean  =  18.0%, range  =  4%–75%) in most specimens of B. fratrorum (86% of total specimens surveyed), and the ventral surface of the tail is white or mottled with brown (the pigment is contained in the scales and tail hairs). By contrast, a short white tail tip occurs in only 20% of all specimens of B. chrysocomus surveyed and is short relative to tail length (mean  =  5.5%, range  =  1%–25%). The undersurface of the tail ranges from brown to heavily mottled brown in most samples—a white ventral surface is uncommon.

Testes size provides a strong contrast between the species (table 9). Relative to length of head and body, the testes of B. chrysocomus are longer (22%), those of B. fratrorum much shorter (8%), a difference also indicated by relative testes mass. Testes mass relative to body mass was measured by Breed and Taylor (2000) and reported as 3.02% in B. chrysocomus (N  =  2) and 0.28% in B. fratrorum (N  =  2).

The two species also differ in spermatozoan morphology. In B. chrysocomus, the falciform sperm head is long and thin with a long tail attaching near the end of the head, but in B. fratrorum, the sperm head is shorter and gently curved, with the tail (which is much shorter than in B. chrysocomus) attached near the middle of its concave surface (Breed and Musser, 1991; Breed and Taylor, 2000).

With the exception of three variables, all cranial and dental dimensions measured are absolutely much greater in B. fratrorum than in B. chrysocomus, a distinction qualitatively marked in illustrations of skulls (figs. 16, 17) and quantitatively expressed by univariate means for 232 B. chrysocomus and 100 B. fratrorum (table 42). Among the three dimensional exceptions, the interorbit is absolutely wider in B. chrysocomus (M  =  6.4 mm) than in B. fratrorum (M  =  6.2 mm), and breadth of the bony palate (M  =  3.8 mm in both species) and length of bulla (M  =  6.4 mm for B. chrysocomus, 6.5 mm for B. fratrorum) are statistically identical in the two species. Set against the absolute size contrast between the two, B. chrysocomus has a conspicuously wider interobital region and bony palate, and a longer bulla relative to all other cranial and dental dimensions measured, proportional distinctions diagrammed previously (fig. 19).

Lower molars of B. fratrorum have a somewhat simpler occlusal topography than do those of B. chrysocomus judged by frequencies of certain cusps and cusplets (table 11). An anterolabial cusp is present on the second molar in only 12% of the sample and all the specimens lack the cusp on the third molar; this cusp is part of the occlusal surface of the second molar in 90% of the sample of B. chrysocomus and occurs on the third molar in 65% of the sample. An anterior labial cusplet is not found on the first molar of all examples of B. fratrorum surveyed, but is usual in about half the sample of B. chrysocomus. The posterior labial cusplet of the first molar occurs in about half the sample of B. fratrorum, but is present in 97% of the series of B. chrysocomus.

Thomas was impressed by the prominent (“beaded”) supraorbital ridges in B. fratrorum compared to B. chrysocomus. Interorbital and postorbital margins are delimited by low ridges on the skulls of both species, and those in B. chrysocomus are not as prominent as in B. fratrorum (figs. 16, 17). The absolute difference is related to size, the much larger skull of B. fratrorum carries with it heavier ridging than does the smaller skull of B. chrysocomus; relative to size of skull, however, prominence of the interorbital and postorbital borders is similar.

The conspicuous contrasts between B. fratrorum and B. chrysocomus in body size, relative length of tail, length of the white tail tip and its frequency in populations, cranial and dental dimensions in absolute and proportional terms, frequencies of cusp and cusplets on lower molars, structure of spermatozoa, relative testes size, and sympatry should dispel any notion that the samples of each represent a single species.

Bunomys fratrorum and B. andrewsi: B. andrewsi has never been collected on the northern peninsula of Sulawesi. It ranges from the southern end of the northern peninsula over the lowlands and highlands of Sulawesi's core, through the southeastern peninsula and on Pulau Peleng at the end of that arm, and into the southwestern peninsula (see the map in fig. 50). Bunomys andrewsi and B. fratrorum are similar in some phenetic characteristics. Both have brownish-gray upperparts lightly speckled with buff and black and grayish-white underparts tinted or washed with a range of buffy tones. Bunomys fratrorum is comparable in lengths of head and body and hind foot to B. andrewsi (table 41). The most conspicuous external difference is expressed in length of tail and its color pattern. The tail is long (means  =  167.5–179.0 mm in six population samples), coequal to length of head and body in samples of B. fratrorum (LT/LHB  =  99%–101%), and most individuals (86% of the sample) show a long and white terminal portion (mean  =  18.0%, range  =  4%–75% of tail length). By contrast, the tail is absolutely shorter in B. andrewsi (mean  =  111.5–156.8 for all population samples; table 41), much shorter relative to length of head and body (LT/LHB  =  75%–92%), a white tip occurs infrequently in the samples (20% of 133 specimens), and when present is short relative to length of tail (mean  =  7.7%, range  =  1%–13%; table 8).

Relative testes size and spermatozoal morphology differ (table 9). Size of testes relative to body size is less in B. fratrorum (8%) compared with the range in B. andrewsi (8%–15%). Spermatozoa of B. fratrorum have a short and gently curved sperm head to which a short tail is attached near the middle of its concave surface (Breed and Taylor, 2000) while B. andrewsi resembles B. chrysocomusis in having a falciform sperm head that is long and thin with a moderately long tail attaching near the base of the head (Breed and Musser, 1991).

Most of the cranial and dental measurements derived from the samples of B. fratrorum average greater than in the combined population samples of B. andrewsi (table 42). Interorbital breadth and expanse of the incisive foramina are exceptions. Bunomys fratrorum has a narrower interorbit (mean  =  6.2 mm) compared with B. andrewsi (mean  =  6.7 mm) and shorter incisive foramina (mean  =  7.3 mm for B. fratrorum, 8.0 mm for B. andrewsi), contrasts evident when skulls of comparable adult age classes are compared (figs. 52–Fig. 53.54).

A scatter plot of specimen scores representing B. fratrorum and B. andrewsi projected on first and second principal components summarizes the morphometric distinctions between the two species (fig. 55, upper graph). The major axes of the two elliptical clouds of scores are phenetically discrete: the regression lines of the second principal component on the first are parallel, their Y-intercepts are significantly different between the two species (+0.951 versus −0.951; F  =  73.62, P  =  0.000), but their slopes are statistically equivalent (−0.406 versus −0.407; F  =  0.00, P  =  0.998). Although there is marginal overlap between the two ellipsoidal clusters of scores along the second axis, there is enough separation to indicate that B. andrewsi has a relatively wider interorbit, narrower rostrum, narrower braincase, shorter but wider bony palate, narrower mesopterydoid fossa, markedly longer and wider incisive foramina, larger bulla and smaller molars compared with B. fratrorum (see the correlations in table 43). The ratio diagram in figure 56 presents most of these same proportional contrasts in graphic form but also shows the braincase of B. andrewsi to be wider relative to its height compared with B. fratrorum, and the molars smaller relative to expanse of the palatal bridge.

Fig. 55.

Specimen scores representing all population samples of Bunomys fratrorum (filled circles; N  =  100), B. andrewsi (empty circles; N  =  98), and B. penitus (filled inverted triangles; N  =  181) projected onto first and second principal components extracted from principal-components analysis of 16 cranial and two dental log-transformed variables. Upper graph: Samples of B. fratrorum are contrasted with all population samples of B. andrewsi. Ellipses outline 95% confidence limits for the cluster centroids. Equations for the regression lines are: B. fratrorum, Y  =  −0.406× 0.951 (F  =  34.30, P  =  0.000); B. andrewsi, Y  =  −0.407× −0.951 (F  =  60.46, P  =  0.000). Lower graph: samples of B. fratrorum are contrasted with all population samples of B. penitus. See table 43 for correlations (loadings) of variables with extracted components and for percent variance explained for both ordinations.

Fig. 56.

Ratio diagrams illustrating some proportional relationships in cranial and dental dimensions between Bunomys fratrorum (the standard, N  =  100) and B. andrewsi (N  =  98), and between B. fratorum and B. penitus (N  =  185). Data were derived from values for mean, standard deviation, and sample size of variables listed in table 42. How the diagram was constructed and how to read it is explained in Materials and Methods.

Frequencies of two structures on the mandibular molars differs betwen samples of B. fratrorum and those representing B. andrewsi (table 11). An anterolabial cusp is present on the second molar in only 12% of the sample of B. fratrorum, but occurs in 88%–100% of the combined samples of B. andrewsi. About half of the sample of B. fratrorum has a posterior labial cusplet on the first molar, but nearly all specimens of B. andrewsi bear this structure (97%–100% of all specimens surveyed).

The morphometric distinctiveness of B. fratrorum relative to B. andrewsi is reinforced by a phenogram based on squared Mahalanobis distances among centroids for all population samples representing Bunomys (fig. 21). The cluster of samples identifying B. fratrorum unites with that of B. karokophilus, n. sp., and those samples link with the clusters of population samples for B. andrewsi and B. penitus. There is no evidence from morphology of skin and skull suggesting that B. fratrorum is a fragment of B. andrewsi isolated in the northeastern segment of the northern peninsula.

Bunomys fratrorum and Bunomys penitus: Within the forests mantling the northeastern end of the northern peninsula, the altitudinal distribution of B. fratrorum stretches from lowlands into mountains. Bunomys penitus inhabits only mountain forests clothing highlands in the west-central mountain block of the island and on the southeastern peninsula. The two species are smililar in body size, but the tail averages slightly longer and is generally longer relative to head and body length in B. fratrorum compared with B. penitus (table 41).

The dorsal pelage of B. penitus is dense and long (up to 25 mm), soft to the touch, silky in appearance, and brownish gray tending toward grayish tones (coat is not as long in B. fratrorum, not longer than 12 mm in most specimens, somewhat courser in texture and not silky, and brownish gray tending toward darker tones). Underparts are dark grayish white (underparts are also grayish white in B. fratrorum but tinged or washed with buffy tones in many specimens). The tail ends in a long white segment, behind it the dorsal surface is glossy grayish brown or brownish gray, and the ventral surface is pure white (dorsal surface is brown in B. fratrorum except for a white terminal segment, the ventral surface ranges from pure white to white speckled with brown to mottled white and brown). Although a white-tipped tail is characteristic of both species (table 8), the white segment is longer relative to tail length in B. penitus (means  =  12.3%–30.7% for six samples of B. penitus; 15.0%–22.0% for four samples of B. fratrorum) and never speckled—some portion of specimens in most samples of B. fratrorum exhibit a speckled distal tail segment. Dorsal surfaces of the feet are white or white suffused with gray; the claws are delicate and nearly concealed by long, dense, and silvery ungual tufts (metatarsal and metacarpal surfaces range from white to brownish white in B. fratrorum, the claws are sturdy and not concealed by ungual tufts.

Testes size relative to head and body is similar in the two species (table 9). Sperm morphology is different. Spermatozoa of B. fratrorum have a short and gently curved sperm head to which a short tail is attached near the middle of its concave surface (Breed and Taylor, 2000) while B. penitus has a falciform sperm head that is long and thin with a moderately long tail attaching near the base of the head (Breed and Musser, 1991).

The skull in the sample of Bunomys penitus averages overall somewhat smaller (indicated by means for occipitonasal length and zygomatic breadth) than that of B. fratrorum, the braincase is not as deep, the zygomatic plate startlingly narrower, the bony palate narrower, and the postpalatal region (basicranium) shorter, as reflected by absolute differences in univariate means (table 42). Means for three internal dimensions are not significantly different between the two species (breadths of rostrum and braincase, and length of diastema), but the interorbit of B. penitus is wider, the rostrum and bony palate longer, the mesopterygoid fossa more spacious, the incisive foramina longer and broader, the ectotympanic bulla larger, and the molars heavier (longer molar row, wider molars).

Separate clouds of specimen scores for B. penitus and B. fratrorum projected on first and second principal components provide a multivariate summary of the contrast between the two species in cranial and dental variables (fig. 55, lower graph). Covariation in interorbital breadth, along with lengths of rostrum, bony palate, incisive foramina, bullar capsule, and molar size (large positive loadings for these variables, r  =  0.33–0.65; table 43) strongly influence the spread and separation of scores along the first axis, and highlights the greater magnitude of these dimensions in B. penitus as compared to B. fratrorum, measurement contrasts reflected by univariate means (table 42).

There are striking proportional differences between B. penitus and B. fratrorum in cranial and dental variables, which are revealed in a ratio diagram (fig. 56). The most conspicuous contrasts involve magnitudes of certain cranial dimensions relative to size of skull (indexed by occipitonasal length): B. penitus is relatively narrower across the zygomatic arches but has a much broader interorbit, the facial region is relatively longer (longer rostrum, incisive foramina, and diastema), the zygomatic plate strikingly narrower, the bony palate longer, the mesopterygoid fossa wider, the bullar capsule larger, and the molars more massive. The elongate facial region is also proportioned differently in that B. penitus has a narrower rostrum, incisive foramina, and bony palate relative to their respective lengths.

Frequencies of certain cusps and cusplets forming parts of the coronal surfaces of molars differ between the two species. No specimen of B. fratrorum I examined shows a large labial cusplet adjacent to or merging with cusp t6 on the first upper molar (such a cusplet is present in 30% of the sample of B. penitus; fig. 75). Cusp t3 is absent from the third upper molar on most examples of both species, is part of the second molar in only 11% of the sample of B. fratrorum, but is present in 62% of the sample of B. penitus (table 10). A posterior labial cusplet is present on the first lower molar in nearly half of the sample of B. fratrorum but in every specimen of B. penitus, and an anterolabial cusp occurs infrequently on the second lower molar in the sample of B. fratrorum (12%) but is present in about half of the sample of B. penitus (55%); see table 11.

Summary of contrasts between population samples of Bunomys fratrorum and those of B. andrewsi and B. penitus: Bunomys fratrorum is found only on the northern peninsula east of the Gorontalo region and inhabits tropical lowland evergreen and montane rain forests; B. andrewsi occurs primarily in tropical lowland evergreen rain forest in Sulawesi's core and the southeastern and southwestern peninsulas; B. penitus is strictly montane, found so far only in the west-central mountain block and Pegunungan Mekongga on the southeastern peninsula. Body size is similar among the species.

Bunomys andrewsi has a shorter tail (both absolutely and relative to combined length of head and body), and a short, white tail tip is present in only a small portion of the sample; tails are longer and often coequal with length of head and body in B. fratrorum and B. penitus, and a long, white tip is usual in both species (tables 8, 41). Bunomys penitus has a longer dorsal coat and grayer underparts; dorsal surfaces of the front and hind feet are typically white rather than white- to brownish gray, the range in the other species; front claws are more robust and ungual tufts are sparse at the bases of front and hind claws in B. andrewsi as well as B. fratrorum compared with the smaller, gracile front claws of B. penitus and its longer ungual tufts.

Absolute and proportional similarities and contrasts in cranial and dental variables between B. fratrorum and the other two species have been presented in the images of skulls (figs 52–Fig. 53.54), univariate summary statistics (table 42) results from principal-components analyses (fig. 55, table 43) and ratio diagrams (fig. 56) previously described. A graphic summary of the morphometric distinctions among the species is portrayed by individual specimen scores projected onto first and second canonical variates (fig. 57). Scores for the three species fall into three discrete clusters. Along the first axis, the group of points representing B. fratrorum is isolated from the other two aggregations by covariation in several cranial and dental variables (moderate to high loadings; table 44) that, compared with B. andrewsi and B. penitus, reflect its more greatly flared zygomatic arches, narrower interorbit, shorter rostrum (compared with B. penitus), higher braincase, much wider zygomatic plate, longer basicranium (measured by postpalatal length) shorter bony palate and incisive foramina, smaller bulla, and smaller molars (compared with B. penitus).

Fig. 57.

Specimen scores representing all population samples of Bunomys fratrorum (filled circles; N  =  100), B. andrewsi (empty circles; N  =  98), and B. penitus (inverted filled triangles; N  =  185) projected onto first and second canonical variates extracted from discriminant-function analysis of 16 cranial and two dental log-transformed variables. See table 44 for correlations (loadings) of variables with extracted canonical variates and for percent variance explained.

Along the first canonical axis, scores for B. penitus form a cluster opposite the clump representing B. fratrorum, which emphasizes the wider interorbit of B. penitus compared with B. fratrorum, its longer rostrum, wider but shallower braincase, much narrower zygomatic plate (which is diagnostic for B. penitus), longer bony palate and incisive foramina, larger bulla, and heavier molars (see the loadings in table 44). The separation of scores denoting B. andrewsi from the aggregations for B. fratrorum and B. penitus along the second axis reflects proportional contrasts and is influenced primarily by the relatively smaller skull of B. andrewsi compared with the other two species, its relatively shorter and narrower rostrum, smaller braincase, wider zygomatic plate, shorter diastema, shorter but wider bony palate, narrower mesopterygoid fossae, and less robust molars (table 44).

The isolation of B. fratrorum from B. andrewsi and B. penitus by morphometric attributes is reinforced by a phenogram derived from squared Mahalanobis distances among centroids for population samples (fig. 21). Population samples for B. andrewsi and B. penitus join in a monophyletic group before linking with those representing B. fratrorum. This picture, along with the phenetic distinctions among the sets of samples evident from inspection of skins and skulls, absolute and proportional contrasts in dimensions, results of other multivariate analyses, and different geographic and altitudinal relationships support the hypothesis that B. fratrorum is a distinct entity with a different genetic history (species) from B. andrewsi and B. penitus. Neither the montane B. penitus nor the lowland and middle-elevation B. andrewsi can be viewed as simply geographic or altitudinal variants (subspecies) of the northern peninsular B. fratrorum. Its closest phenetic relative, judged by the pattern seen in the Mahalanobis distance cluster, may be the central Sulawesian B. karokophilus, n. sp. (see that account).

Geographic Variation

Variation in external traits among samples of B. fratrorum does not conform to any obvious geographic pattern. The range of variation of coat color and thickness, tail pattern, and external dimensions within any one of the three largest samples of B. fratrorum I studied (those from Teteamoet, Kuala Prang, and Temboan; see table 41) matches the extent of variation in these variables present among all the population samples except one. The three specimens collected above 1800 m in montane forest on Gunung Klabat have slightly longer and darker fur covering the upperparts of head and body.

Morphometric variation in cranial and dental variables does exist among population samples as results of principal-components and discriminant-function analyses illustratrate. A scatter plot defined by first and second principal components encloses specimen scores scattered along the two axes generally without forming perceptible patterns (fig. 58). Scores for the Teteamoet and Temboan samples fill the multivariate space, overlapping points for nearly all the other samples. The spread along the first component is influenced primarily by size, as signified by the moderate to high positive correlation coefficients (r  =  0.32–0.78) of most cranial variables (table 46) and likely mostly reflects age and individual variation within the range of adult cohorts from young to old. The filled square at the top of the scatter plot along the second axis denotes an adult from Gunung Mogogonipa with an exceptionally long bony palate and short incisive foramina (r  =  0.72 and −0.53, respectively; table 46).

Fig. 58.

Specimen scores representing six population samples of Bunomys fratrorum projected onto first and second principal components extracted from principal-components analysis of 16 cranial and two dental log-transformed variables. Symbols: filled circles  =  Teteamoet (N  =  33); empty circles  =  Kuala Prang (N  =  27); filled triangles  =  Gunung Klabat (N  =  2); asterisk  =  Rurukan (N  =  1; holotype of Mus fratrorum); empty triangles  =  Temboan (N  =  33); filled squares  =  Gunung Maujat + Gunung Mogogonipa (N  =  4). Correlations (loadings) of variables with extracted components and percent variance explained are listed in table 46.

A different view of covariation in cranial and dental variables among population samples is provided by individual specimen scores projected on first and second canonical variates in which scores for the larger samples form a pattern related to geographic provenance (fig. 59; table 46). Points identifying specimens from Teteamoet and Kuala Prang, located at the northeastern tip of the northern peninsula (localities 1 and 5 on the map in fig. 50), form a cluster in the right half of the ordination along the first axis that marginally overlaps the cloud of scores in the left half of the scatter plot designating specimens from Temboan (locality 17 on the map in fig. 50), which lies far to the southwest of Kuala Prang and Teteamoet, and Maujat + Mogogonipa, highlands west of Temboan (localities 18 and 19 on the map in fig. 50). Scores for the holotype from Rurukan clusters with the Teteamoet sample, the two representing Gunung Klabat are contained in the Temboan cluster. Pattern of the scores reflects the slightly larger skulls (indexed by occipitonasal length and zygomatic breadth) in the Kuala Prang and Teteamoet samples, their deeper braincase, longer postpalatal region and incisive foramina but shorter bony palate compared with the Temboan and Maujat + Mogogonipa samples as signified by the larger positive and negative loadings for these variables on the first axis listed in table 46 (and reflected by univariate means in table 45). Intersample variation summarized in the canonical variates ordination suggests a gradient in skull size from east to west within the range of B. fratrorum.

Fig. 59.

Upper graph: Individual specimen scores projected onto first and second canonical variates extracted from discriminant-function analysis of of 16 cranial and two dental log-transformed variables derived from six population samples of B. fratrorum. Symbols: filled circles  =  Teteamoet (N  =  33); empty circles  =  Kuala Prang (N  =  27); filled triangles  =  Gunung Klabat (N  =  2); asterisk  =  Rurukan (N  =  1; holotype of Mus fratrorum); empty triangles  =  Temboan (N  =  33); filled squares  =  Gunung Maujat + Gunung Mogogonipa (N  =  4). See table 46 for correlations (loadings) of variables with extracted canonical variates and for percent variance explained. Lower diagram: Pattern of phenetic relationships among six population samples of Bunomys fratrorum derived from UPGMA clustering of squared Mahalanobis distances among group centroids that was derived from discriminant-function analysis.

Cluster analysis derived from average Mahalanobis distances (squared) among centroids for population samples also illustrate a close relationship between samples from Teteamoet and Kuala Prang, the localities close to one another, and these link to Temboan. Samples from Gunung Klabat and Rurukan cluster, and these places are geographically near one another (see the map in fig. 50). The westernmost sample from Gunung Maujat and Gunung Mogogonipa is distant from the other five population samples in the cluster diagram, an arrangement suggested by the position of scores in the canonical variate scatter plot where scores identifying the four specimens from Maujat and Mogogonipa lay at the far left margin of the total scatter of scores.

The population samples for B. fratrorum come from two regions of the northern peninsula that are deemed areas of endemism as illustrated by macaques (Fooden, 1969), toads (Evans et al., 2003a), and fanged frogs (Evans et al., 2003a, 2003b). The northeastern end of the peninsula from the tip west to approximately the drainages of the Sungai Onggak Mongondaw and Sungai Onggak Dumoga describes one endemic region (“northeast”) and it is where the specimens of B. fratrorum from Teteamoet, Kuala Prang, Gunung Klabat, Rurukan, and Temboan were obtained. Those samples are closely linked (in Mahalanobis distance units) compared with the distant position of the samples from Gunung Maujat and Gunung Mogogonipa, which were collected to the west in the “north central” endemic region, approximately between Sungai Onggak Dumoga and the Gorontalo area (see fig. 1). But the Maujat and Mogogonipa samples are small, consisting of two adults, a young adult, and very young adult. Study of larger samples from the “north central” segment along with collections from the region between Gunung Maujat-Gunung Mogogonipa and the eastern site of Temboan will be required to determine whether the populations living between Sungai Onggak Dumoga and the Gorontalo area are a separate species, a morphometrically definable geographic variant of B. fratrorum inferring some degree of genetic isolation, or simply another geographic sample of that species genetically connected to populations occurring to the east. In the context of such an inquiry the use of DNA sequences would be most welcome.

Most examples of B. fratrorum come from altitudes below 1000 m in tropical lowland evergreen rainforest habitats. A few were collected at higher elevations in lower montane forest on Gunung Maujat (at 1780 m) and Gunung Klabat (at 1829 and 1982 m). It is significant that study of skin and skulls along with results of multivariate analyses place these specimens with other population samples of B. fratrorum and not with any other species of Bunomys (see particularly the cluster diagram in fig. 21, showing phenetic relationships among all species of Bunomys based on squared Mahalanobis distances among centroids for population samples). Within its range, B. fratrorum is not replaced in montane forest formations by another species of Bunomys. This elevational distribution contrasts with the pattern demonstrated by other species in the B. fratrorum group occurring elsewhere on Sulawesi. In the northern part of the west-central region of Sulawesi's core, for example, tropical lowland evergreen rainforest habitats are occupied by B. andrewsi and B. karokophilus, n. sp., and these two species are replaced by B. penitus at higher elevations in lower and upper montane forests. Bunomys andrewsi also inhabits lowland habitats on the southeastern peninsula and is replaced by B. penitus at higher elevations there in montane forest habitats. That B. fratrorum is the only large-bodied species of Bunomys found in both lowland and montane evergreen rain forests on the northern peninsula of Sulawesi may be related to past periodic fluctuations in sea level and tectonic activity that isolated the region east of Gorontalo as one or more islands (Fooden, 1969). One of those islands may have supported a population of ancestral Bunomys from which B. fratrorum evolved in isolation from populations on mainland Sulawesi. Modern samples of B. chrysocomus represent the only other species of Bunomys currently recorded from the northeastern tip east of Gorontalo and may be a relatively recent immigrant to that region.

Natural History

I have no first-hand experience with B. fratrorum and no information from the collector's field journals. The species occupies habitats in tropical lowland evergreen and montane rain forests and, as is usual with the other species of Bunomys, is likely terrestrial and nocturnal.

I can provide a bit of data about diet. Fortunately, H.C. Raven preserved an adult male in fluid (USNM 217084) that he caught at Teteamoet on the coastal plain (locality 1 in the gazetteer and on the map in fig. 50). The stomach contains remains of up to five small earthworms, fragments of a small adult beetle, head of a termite, and pieces of a small unidentified fruit. The composition of items is similar to that constituting the diet of B. chrysocomus and B. andrewsi (see those accounts and table 13).

Spermatozoa of B. fratrorum have been used in several inquiries. Body and testes weights (mass) along with sperm size was derived from two B. fratrorum by Breed and Taylor (2000) and employed in an investigation of murines designed “to test the hypothesis that differences in relative testes mass, and perhaps sperm size, relate to interspecific differences in the amount of intermale sperm competition and in breeding systems.” Related studies in which spermatozoa of B. fratrorum was included investigate morphometry, competition, cooperation, and sociality in rodent sperm (Immler et al., 2007; Pizzari and Foster, 2008).

Ectoparasites

Bunomys fratrorum is parasitized by sucking lice, fleas, ticks, and chiggers (table 14). Of the sucking lice, Hoplopleura sembeli has also been recorded from the endemic Sulawesi rats Maxomys hellwaldii and Rattus hoffmanni (Durden, 1990; Durden and Musser, 1991), and Polyplax wallacei also parasitizes Bunomys chrysocomus and a species of Taeromys (Durden, 1990; Durden and Musser, 1991).

Of the species in the four genera of fleas (Siphonaptera) that parasitize B. fratrorum, Sigmactenus sulawesiensis (Leptopsyllidae) also parasitizes four other endemic Sulawesi murines (Bunomys fratrorum, Eropeplus canus, Maxomys musschenbroekii, and Paruromys dominator) and the endemic tree squirrel Prosciurillus topapuensis (Durden and Beaucournu, 2000). Sigmactenus alticola crassinavis also infests a native shrew (Crocidura sp.) and the endemic murines, Maxomys musschenbroekii, Paruromys dominator, Rattus hoffmanni, and R. xanthurus (Durden and Beaucournu, 2000). Musserella, n. gen. and species #4 (Pygiopsyllidae), infests not only Bunomys fratrorum, but also five other Sulawesi endemic murids (Bunomys chrysocomus, Rattus hoffmanni, Paruromys dominator, Maxomys hellwaldii, and M. musschenbroekii) and the nonnative Rattus tanezumi (Durden, in litt., 2008). Nestivalius sulawesiensis (Pygiopsyllidae) is recorded from Bunomys fratrorum and B. chrysocomus; Maxomys hellwaldii and M. musschenbroekii; and Rattus facetus (recorded as R. marmosurus) and R. hoffmanni (Mardon and Durden, 2003). Finally, Macrostylophora theresae also infests Paruromys dominator and Rattus xanthurus (Durden and Beaucournu, 2006).

Bunomys fratrorum is host to the immature stages of species in three genera of ticks (Acari: Ixodoidea): Amblyomma sp., Dermacentor sp., Haemaphysalis hystricis, and Haemaphysalis sp. (Durden et al., 2008). In addition to Bunomys fratrorum, immatures of members of these three tick genera have been collected from a suite of other mammal hosts living in Sulawesi: shrews (the endemic Crocidura sp. and Crocidura elongata, and the commensal Suncus murinus), pigs (Sus celebensis, endemic, and the domestic Sus scrofa), rusa (Rusa timorensis, nonnative), water buffalo (Bubalus bubalis, nonnative), domestic dog (nonnative), three endemic squirrels (Rubrisciurus rubriventer, Hyosciurus heinrichi and H. ileile), 12 species of endemic murid rodents (Bunomys chrysocomus and B. andrewsi; Margaretamys beccarii; Echiothrix centrosa; Maxomys hellwaldii, M. musschenbroekii, and M. wattsi; Paruromys dominator; Taeromys sp.; Rattus hoffmanni, R. xanthurus, and R. facetus [recorded as R. marmosurus]), and four nonnative murines (Mus musculus; Rattus tanezumi [recorded as R. rattus], R. argentiventer, and R. exulans); whereas adults have been recorded from pigs (Sus celebensis, Sus scrofa), rusa (Rusa timorensis), water buffalo (Bubalus bubalis), and domestic dog (Durden et al., 2008).

Four species of chiggers (Acari: Trombiculidae) are known to parasitize Bunomys fratrorum (Goff et al., 1986; Goff and Durden, 1987; Whitaker and Durden, 1987). Schoengastia sulawesiensis is also found on Maxomys musschenbroekii and Rattus hoffmanni. Walchiella oudemansi also parasitizes Bunomys chrysocomus and the nonnative Rattus exulans). Leptotrombidium deliense has also been recorded from the endemic rats Bunomys chrysocomus, Maxomys musschenbroekii, Paruromys dominator, Rattus hoffmanni, and Rattus xanthurus. Finally, Gahrliepia lupella infests Maxomys musschenbroekii in addition to Bunomys fratrorum.

Synonyms

No other scientific names have been proposed that apply to B. fratrorum.

Bunomys andrewsi, the next species to be discussed, is not all that different from B. fratrorum in fur color and physical size, but judged by dimensions of the skull and molars is phenetically more like the montane B. penitus than B. fratrorum (see fig. 21), and has been recorded only from the southern half of Sulawesi where it occurs primarily in tropical lowland evergreen rain forest.

Bunomys andrewsi (Allen, 1911)

Mus andrewsi Allen, 1911: 336.

Rattus adspersus Miller and Hollister, 1921a: 71.

Rattus penitus inferior Tate and Archbold, 1935a: 6.

Rattus penitus heinrichi Tate and Archbold, 1935a: 6.

Holotype

USNM 175899, the skin and skull of an old adult male (original number 25) collected December 13, 1909, by R.C. Andrews. In the original description, Allen (1911: 336) referred to the holotype as 32193. That is a misprint for 31293, which is the number given to the specimen by staff at the American Museum of Natural History, where it was initially deposited and cataloged. Standard external measurements, other relevant data, and measurements of the skull and dentition are listed in table 40. The skin is overstuffed but intact, the cranium and mandible are complete except for missing hamular processes in the pterygoid region, all incisors and molars are present (fig. 60).

Fig. 60.

The holotype of Bunomys andrewsi (USNM 175899), an old adult male from Pulau Buton, off the southern coast of the southeastern peninsula. ×2.

Type Locality

Pulau Buton (05°00′S, 122°55′E; locality 23 in the gazetteer and on the map in fig. 50) southeastern region of Sulawesi, Propinsi Sulawesi Tenggara, Indonesia.

Emended Diagnosis

A member of the B. fratrorum group resembling the other species in that assemblage in body size (LHB  =  137–195 mm, WT  =  95–222 g, ONL  =  37.1–45.5 mm) and further characterized by the following combination of traits: (1) a relatively long muzzle and broad face, and stocky body; (2) dorsal fur dense, lustrous, dark brown speckled with buff and black, ventral fur grayish white to buffy gray or ochraceous gray, digits white, dorsal surfaces of carpal and metacarpal regions typically white, range from grayish white to grayish buff in some samples; (3) claws on front feet short but not as short and delicate as in B. penitus, scanty ungual tufts at bases of front and hind claws; (4) tail shorter than length of head plus body (LT/LHB  =  75%–92%), dark brown on dorsal surface, white through mottled brown to solid brown on ventral surface (5) white tail tip uncommon (characterizes 20% of 127 specimens) and when present is short relative to tail length (mean  =  7.7%, range  =  1%–13%); (6) testes moderately small relative to body size (8%–15%); (7) shape of sperm head similar to that of B. chrysocomus but shorter and slightly wider; (8) robust skull with a moderately long and narrow rostrum, wide upright zygomatic plate, long incisive foramina (actually and relative to length of skull), and moderately large ectotympanic bulla relative to skull size; (9) molars moderately large relative to size of skull and mandible; (10) cusp t3 occurs frequently on second upper molar (78%) in sample from southwestern peninsula but infrequently (17%) elsewhere; (11) anterolabial cusp characteristically present on second lower molar (94% of sample) but occurs infrequently on third lower molar (18%); (12) anterior labial cusplets typically absent from first lower molars, posterior labial cusplets typically present on first and second molars; and (13) karyotype, 2N  =  42, FNa  =  56, FNt  =  58.

Geographic and Elevational Distributions

Labuan Sore (00°37′S, 120°03′E) at the southern terminus of the northern peninsula is the northernmost record of B. andrewsi. South of there voucher specimens indicate the species occurs in lowlands and mountains of Sulawesi's core, on the eastern peninsula, the two southern peninsulas, and on Pulau Buton off the coast of the southern margin of the southeastern peninsula (see the map in fig. 50).

Reliable elevations associated with each specimen document 30 m to 1600 m as the range in which most collections have been made. The upper limit is anchored by animals recently collected by Kevin Rowe (Museum Victoria) and Anang Achmadi (Museum Zoologicum Bogoriense) from the Mamasa area on Gunung Gandangdewata (see the gazetteer and table 6). Most of the specimens reported from there are from tropical lowland evergreen rain forest, but some were taken in the transition between lowland evergreen and montane forest habitats.

Collections of small mammals from the northern peninsula north of Labuan Sore (at the base of the peninsula) do not contain examples of Bunomys andrewsi. The narrow stretch of coastal lowlands and mountains between Labuan Sore and the northwest curve of the peninsula has not been adequately (if at all) surveyed for small mammals; whether B. andrewsi occurs there is unknown. The remainder of the northern peninsula, however, has been surveyed periodically by different collectors dating from the late 19th century and into the 20th century (the Sarasins, G. Heinrich, H.C. Raven, and J.J. Menden, for example), but no collections made then, some of which are large in number of specimens and diversity of taxa, include B. andrewsi. The northeastern section of the northern peninsula, that stretches east of the Gorontalo region, has been the focus of relatively intense collecting efforts by Dutch, English, German, Indonesian, and North American naturalists, and only B. fratrorum and B. chrysocomus have been documented from this region (see the gazetteers and distribution maps for these species).

The peninsular neck between Palu and Parigi, where Labuan Sore is located, may approximate the natural northern range boundary for B. andrewsi. That region is the southern limit for the geographic distribution of the tree squirrel, Prosciurillus leucomus (at Bumbarujaba, 00°43′S, 120°04′E; Musser et al., 2010) and confluence of the ranges for the northern peninsular Macaca hecki and southern Sulawesi Macaca tonkeana (Fooden, 1969; Watanabe et al., 1991; Bynum et al., 1997; Groves, 2001). Results of future surveys for small mammals in this southern region of the northern peninsula would be most revealing.

Sympatry with Other Bunomys

Except for B. fratrorum, which is restricted to the northeastern end of the northern peninsula and is sympatric only with B. chrysocomus (see that account), the ranges of all other species of Bunomys fall within the broad geographic distribution for B. andrewsi (table 6). But little or no overlap (syntopy) characterizes the ranges of B. andrewsi and the other species. The usual pattern has populations of B. andrewsi occurring in lowlands and those of other species existing at higher elevations (elevationally parapatric). Three pairs of distributions form examples. At the western margin of the eastern peninsula, B. andrewsi has been collected in the lowlands (Sungai Ranu, 50–100 m) and B. chrysocomus and B. prolatus only much higher on the adjacent Gunung Tambusisi (1372–1830 m). On the western side of the southeastern peninsula, B. andrewsi is documented from Wawo and Masembo in lowlands (50–550 m) adjacent to Pegunungan Mekongga, and B. penitus and B. chrysocomus are found in montane forest on that mountain (1500–2000 m). Bunomys andrewsi and B. coelestis are found on Gunung Lompobatang at the southern end of the southwestern peninsula where B. andrewsi was collected on the lower flanks up to 1100 m and B. coelestis higher on the volcano between 1830 and 2500 m.

Certain collections of B. andrewsi and B. chrysocomus provide the only reliable syntopic distributional records between the former and any other species of Bunomys (table 20). Both species were collected in the northern part of the west-central mountain block at Bakubakulu, 600 m, in the Puro Valley. Along my transect between 290 and 675 m I collected examples of each in the same trapline. I did not encounter B. andrewsi at higher elevations where B. chrysocomus was common. Subfossil remains of both species have been excavated from Ulu Leang I, a cave on the coastal plain at the southern end of the southwestern peninsula (see the account of B. chrysocomus for additional information covering distributional sympatry or overlap between that species and B. andrewsi).

Bunomys andrewsi and B. penitus are regionally sympatric in the west-central mountain block but generally occur at contrasting elevations and forest formations. Most samples of B. andrewsi were obtained through an elevation range extending from about 100 to 1000 m and were caught in habitats associated with tropical lowland evergreen rain forest. Bunomys penitus is tied to montane forests: 1285–2287 m brackets the elevations at which samples were collected. There are no reliable records that document collection of the two species at the same place (syntopic).

Bunomys andrewsi is locally sympatric with B. penitus and B. torajae on Gunung Gandangdewata in the Quarles Range in the southern part of the west-central mountain block. Bunomys penitus and B. torajae were encountered in montane habitats between 2000 m and 2600 m, B. andrewsi was collected at 1600 m in tropical lowland rain forest.

Description

The original description of Mus andrewsi, obviously named after the collector, is based on two specimens, an old adult and a young adult. The older one is the holotype and Allen (1911: 336) described it as follows:

Allen then provided some measurements, noted a few features of the younger specimen and remarked that

Adult Bunomys andrewsi has a broad head, unpigmented rhinarium and lips, a stocky body, and in physical size (LHB  =  137–195 mm, LT  =  110–167 mm, LHF  =  35–44 mm, LE  =  22–30 mm, W  =  95–222 g, ONL  =  37.1–45.5 mm) resembles the other members of the B. fratrorum group (see the portrait of B. andrewsi in fig. 6). The dorsal coat is soft and moderately long (12–15 mm long on specimens taken in lowlands, up to 20 mm on rats from higher elevations). Guard hairs barely project beyond the overhair layer so the surface of the coat appears smooth; the texture is similar to that in B. chrysocomus. Overall color is a rich dark brown or brownish gray speckled with buff and black (underfur is gray and tipped with pale buff, overhairs are gray basally and tipped with buff, guard hairs provide the black peppering). Sides of the body are slightly paler but show more rusty and buffy highlights. Forearms are the same color as sides of body, except for a grayish brown to dark brown area 8–10 mm behind the wrist that contrasts with the metacarpal surfaces and grayish underparts.

The demarcation between coloration of dorsal and ventral coats is subtle in some animals where the underparts are dark buffy or ochraceous gray, but conspicuous in others where the ventral coat is primarily grayish white. Coloration of underparts is individually variable, but a similar chromatic range can be found in all large samples. At one end of the range is the darkest, dark grayish white (hairs are dark gray for most of their lengths, unpigmented at their tips) or dark grayish buff (hairs have buffy tips), which occurs most frequently in highland samples. The other extreme is pale grayish white or pale grayish-buff underparts (hairs are pale gray with either unpigmented or buffy tips), and predominates in lowland samples. In any large lowland series, the venter coloration is broken by white or buff strips on the chest, along the midventral region in some specimens, at the inguinal area in others. Two specimens from Lombasang are brighter than any of the total specimens I have studied, one has bright buffy gray underparts, the other bright ochraceous-gray ventral fur. On many specimens in samples from low elevations (Pinedapa, Kuala Nausu, Sungai Ranu, Masembo, and Wawo) there are dense orange or rusty patches or strips on the throat and chest, or the inguinal region, or scattered over the abdomen. One adult from Kuala Navusu has a cream venter slightly suffused with pale gray and is rusty around the chin and throat and pale rusty over the neck and chest.

Two samples from about 1000–1500 m deserve additional attention. Except for two specimens, underparts in the sample from Lombasang on the southwestern peninsula show the range in coloration typically seen in series from other places and lower elevations, but just darker: dark grayish white to grayish buff. Two rats have brighter coats, one is buffy gray everywhere, the other ochraceous gray. No specimen in the sample has rusty patches. Specimens in the sample from the Mamasa region (locality 19 in the gazetteer and on the map in fig. 50) have a thicker dorsal coat (15–20 mm) that is darker than lowland samples (the overhairs and their gray segments are longer, imparting a darker tone to the pelage) and darker than the Lombasang series. Underparts are also dark, ranging from dark grayish white to dark grayish buff, and two rats exhibit rusty patches on the neck and chest, similar to the pattern in lowland samples; otherwise, the only difference between this series and those from lower altitudes is the longer, darker pelage.

Ears (external pinnae) are moderately large and appear naked but are covered in short, fine, and unpigmented hairs. In life, the ears have a rubbery texture and are pigmented with gray and brown hues—the range extends from dark gray through brownish gray to dark brownish gray. The dried ears of stuffed museum skins have lost the rubbery texture of the live animal and dried to dark brown with no hint of the actual range in hue and tone.

A tail shorter than the combined length of head and body (LT/LHB  =  75%–92%) is typical for B. andrewsi, and the tail is relatively shorter than in samples of the other three species in the B. fratrorum group (table 41). Grayish brown to very dark brown is the range over the dorsal surface of the tail. The ventral surface exhibits the range from all white (from base to tip, and the tail appears conspicuously dorsoventrally bicolored) to monocolored brown or brownish gray. Intermediate variations range from tails that are gray or tan along the ventral surface to surfaces that are mottled pale grayish brown (all of each scale with brown pigment) or speckled with brown (pigment in center of scale). In most samples, the brown on the dorsal surface extends to the tail tip and individuals showing a white tip are uncommon (20% of 133 specimens), and when present the white tip is short relative to length of tail (mean  =  7.7%, range  =  1%–13%; see table 8). The gray cast to the dorsal surface of the tail is evident in freshly caught rats, but is lost in the dry study skins where the dorsal surfaces appear brown.

Front and hind feet are long and slender. Front and hind digits are white, dorsal carpal and metacarpal surfaces are white, white lightly speckled with brown (hairs are brown at tips), or white speckled with brownish orange. The naked palmar and plantar surfaces are either unpigmented or show gray or pale brown tones. Claws are unpigmented, those on the front digits are, relative to lengths of the digits, about the same size as in B. fratrorum and larger than the delicate claws of B. penitus; a sparse ungual tuft springs from the base of each front and hind claw.

Females have four teats, arranged in two inguinal pairs, the number of teats common to all species of Bunomys. The scrotal sac of males is gray and sparsely haired (appears naked), and the testes are small relative to body size (8%–15%; see table 9). Description of gross spermatozoal morphology is provided by Breed and Musser (1991).

The dorsal coat of juveniles is shorter (up to 10 mm long) than that of adults, the hairs are finer, and the overall color is darker, without the buffy highlights of the adult coat. Underparts are grayish white. The range in coloration of the feet and tail matches that seen in samples of adults.

Bunomys andrewsi typically has a large skull with a long and narrow rostrum and a wide zygomatic plate (figs. 52–Fig. 53.54, 60; tables 42, 51). The interorbit and braincase is moderately wide, the incisive foramina very long (but their posterior rims remain anterior to front surfaces of the first molars), as is the wide bony palate. Each dentary is robust and similar in shape to those of the other species in the B. fratrorum group.

Moderately large molars with simple occlusal patterns are typical of B. andrewsi (fig. 61). The frequencies of cusp t3 are geographically variable. It is present on the second upper molar in only 17% of 70 specimens from the central core and rarely occurs on the third molar in that sample (4%). By contrast, cusp t3 is present on the second molar in 78% of 18 specimens from Lombasang on the southeastern peninsula and exists on the third molar in 22% of that sample (table 10). As in most other species of Bunomys, an anterior labial cusplet is absent from the first lower molar, but a posterior labial cusplet typically forms part of the chewing surfaces of both the first and second lower molars (fig. 57; table 11). An anterolabial cusp is present on the second lower molar in most specimens (94% of 71 individuals) but is less prevalent on the third molar (18% of 66 specimens).

Fig. 61.

Occlusal views of right maxillary (left pair) and mandibular (right pair) molar rows from two specimens of Bunomys andrewsi collected at Kuala Navusu. A, very young adult showing slight wear (AMNH 225660; CLM1–3  =  7.1 mm, clm1–3  =  7.5 mm). B, typical degree of wear in an adult (AMNH 225659; CLM1–3  =  7.1 mm; clm1–3  =  7.4 mm). Note the absence of cusp t3 from the second upper molar, a configuration present in 83% of the specimens from Sulawesi's core (where Kuala Navusu is located) and southeastern peninsula, but not for the sample from the southwestern peninsula where cusp t3 occurs in 78% of the sample; cusp t3 typically occurs at a low frequency on the third upper molar in all samples (table 10).

Karyotype

2N  =  42, FNa  =  56 and FNt  =  58, comprised of seven pairs of metacentric chromosomes, one pair of subtelocentrics, and 12 pairs of acrocentrics; the sex chromosomes are acrocentrics (table 12).

Comparisons

Bunomys andrewsi resembles the northeastern peninsular B. fratrorum in color of body fur, but the dissimilarities in the two species, as described in the account of B. fratrorum, are otherwise trenchant and no data suggests that samples of B. andrewsi are simply southern Sulawesi variants of B. fratrorum. In the Mamasa region, B. andrewsi and B. torajae are sympatric but elevationally separated, and morphologies of the two were contrasted in the account of B. torajae.

Outside of B. fratrorum and B. torajae, B. andrewsi requires comparison with three members of the B. chrysocomus group, and with B. penitus and B. karokophilus, n. sp., in the B. fratrorum group. Contrasts between B. andrewsi and B. karokophilus, n. sp., will take place in the account of the new species. Here I compare B. andrewsi first with B. penitus, then with B.chrysocomus, B. coelestis, and B. prolatus.

Bunomys andrewsi and B. penitus: The distribution of B. penitus takes in Pegunungan Mekongga on the southeastern peninsula and the montane forests in the west-central mountain block in Sulawesi's core (see the map in fig. 51). Samples of B. andrewsi describe a more expansive range: lowlands on the southeastern peninsula and Pulau Buton, lowlands at the western end of the eastern peninsula, low and middle elevations in the mountains of Sulawesi's core, and middle elevations at the southern end of the southwestern peninsula (see the map in fig. 50). I compare all these samples with those of B. penitus. Of the four taxa associated with B. andrewsi, two were described as subspecies of “Rattus penitus.” On the southeastern peninsula, the samples of B. andrewsi from Wawo and Masembo in lowlands immediately adjacent to Pegunungan Mekongga are geographically closest to the Mekongga population of B. penitus. This sample of B. andrewsi was described as “Rattus penitus inferior” by Tate and Archbold (1935a), “inferior” referring to what they viewed to be a lowland population of the montane B. penitus. “Rattus penitus heinrichi” was applied by Tate and Archbold (1935a) to the sample of B. andrewsi from the flanks of Gunung Lompobatang at the southern end of the southwestern peninsula. Bunomys penitus does not occur in montane habitats on that arm of Sulawesi; presumably, Tate and Archbold thought of “heinrichi” as a geographic form of the central Sulawesi penitus. Miller and Hollister's (1921a) “Rattus adspersus” is based on a sample of B. andrewsi from the northern lowlands of Sulawesi's core; B. penitus is common in montane habitats of that region. The two specimens on which “Mus andrewsi” (Allen, 1911) is based were collected on Pulau Buton where B. penitus does not occur.

Bunomys penitus is physically similar to B. andrewsi, averaging slightly longer in lengths of head and body and hind foot, but broadly overlapping in length of ear and mass (table 41). The greatest dimensional contrast between the two species involves tail length, which is absolutely longer in B. penitus (M  =  159.8–171.8 mm) compared with B. andrewsi (mean  =  111.5–156.8 mm) and longer relative to length of head and body (LT/LHB  =  88%–102% for B. penitus, 75%–92% for B. andrewsi). The montane species clashes with the lowland form in its soft, long (up to 25 mm) and silky brownish-gray to grayish-brown dorsal pelage (dorsal coat up to 12 mm thick in most examples of B. andrewsi, soft but not silky, dark brownish gray tinged with bright buff); grayish white ventral coat (underparts in B. andrewsi are dark grayish white, grayish buff, or gray washed with brighter ochraceous hues); its tail that is grayish brown to brownish gray on the dorsal surface behind a white tip, and pure white over the ventral surface (brownish gray on top, ranges from white to brown below in B. andrewsi); and a white tail segment present in 98% of the sample that is long relative to tail length (mean  =  21%, range  =  3%–68%; a white tip is present in only 20% of the combined samples of B. andrewsi and when present is short relative to length of tail, mean  =  7.7%, range  =  1%–13%; table 8).

Size of testes relative to head and body (table 9) and gross spermatozoa morphology (Breed and Musser, 1991) differ between the two species. Bunomys andrewsi averages larger testes relative to body size (8%–15% for four samples) than does B. penitus (9%; the sample is from the west-central mountain block; I have not seen fluid-preserved material from Pegunungan Mekongga). Both have an asymmetrical sperm head falciform in outline and a tail; the head is slightly longer, the apical hook much shorter, and the tail shorter in B. penitus (specimens from Gunung Kanino) than in B. andrewsi (an example from Kuala Navusu).

Both species have a 2N of 42, but different fundamental numbers (FNa  =  56 and FNt  =  58 for B. andrewsi, FNa  =  58 and FNt  =  60–61 for B. penitus; table 12).

The skull averages longer in samples of Bunomys penitus compared with population samples of B. andrewsi, and univariate means for all but six cranial and dental dimensions are also greater in B. penitus (table 42). By contrast, breadth across the zygomatic arches is less in B. penitus than in B. andrewsi, and its zygomatic plate is appreciably narrower. Postpalatal length and length and breadth of the incisive foramina are the same in the two species. See the skull illustrations for visual appreciation of these dimensional similarities and differences (figs. 52–Fig. 53.54).

Specimen scores projected on first and second principal components provides a graphic quantitative summary of differences among the cranial and dental variables (fig. 62, upper graph). Covariation in nearly all variables, as expressed by their high and positive correlation coefficients (r  =  0.42–0.79; table 47), is responsible for the presence of two clusters with very narrow overlap situated along the first axis, scores for the larger skulls of B. penitus to the right, scores for the smaller B. andrewsi to the left. Particularly influential values reflect the appreciably longer and wider rostrum of B. penitus, its longer bony palate, wider mesopterygoid fossa, larger bullae, and heavier molars. Negative loadings for breadths of zygomatic plate and bony palate indicate how much narrower, absolutely and relative to skull size, are these dimensions in B. penitus compared with B. andrewsi.

Fig. 62.

Specimen scores representing all population samples of B. andrewsi (empty circles; N  =  98), Bunomys penitus (filled inverted triangles; N  =  185), and B. chrysocomus (filled triangles; N  =  232) projected onto first and second principal components extracted from principal-components analysis of 16 cranial and two dental log-transformed variables. Upper graph: B. andrewsi contrasted with B. penitus. Scores for holotypes associated with B. andrewsi: “Rattus adspersus” (filled square), “Mus andrewsi” (filled left-pointing triangle), “Rattus penitus heinrichi” (filled diamond), “Rattus penitus inferior” (filled circle). Scores for holotypes linked to B. penitus: “Rattus penitus” (hollow inverted triangle), “Rattus sericatus” (hollow square). Lower graph: B. andrewsi compared with B. chrysocomus. Equations for the regression lines are: B. chrysocomus, Y  =  1.140× 0.873 (F  =  107.32, P  =  0.000); B. andrewsi, Y  =  1.075× −1.984 (F  =  145.31, P  =  0.000). See table 47 for correlations (loadings) of variables with extracted components and for percent variance explained for both ordinations.

The distribution of scores in the ordination affirms identities of the holotypes (and by extension the sample of which each is a part) associated with each species. Scores for holotypes of “Rattus penitus inferior” and “Rattus penitus heinrichi” fall within the constellation representing all population samples of Bunomys andrewsi, as are the points for holotypes of “Rattus adspersus” and “Mus andrewsi.” Holotypes of “Rattus penitus” and “Rattus sericatus” are indicated by two scores in the center of the cloud of points defining B. penitus.

There are three qualitative dental distinctions between B. andrewsi and B. penitus. The first is the absence of a large labial cusplet adjacent to cusp t6 on the first upper molar in all examples of B. andrewsi I examined; such a cusp is found in 30% of the sample of B. penitus (fig. 75). Second is the frequency of occurrence of cusp t3 on the second upper molar (table 10), which is rare in most samples of B. andrewsi (17%; fig. 61) but relatively common in the sample of B. penitus (62%; fig. 75). Third is frequency of the anterolabial cusp on the second and third lower molars (table 11). That cusp forms part of the anterolabial margin of the second molar in most examples of B. andrewsi (94%) but is pesent in only about half the sample of B. penitus (55%); it is found infrequently on the third molar in the sample of B. andrewsi (18%) but is absent from all specimens surveyed of B. penitus.

Bunomys andrewsi and B. chrysocomus: As documented by modern samples, both species are regionally sympatric at the southern end of the northern peninsula, the western margin of the eastern peninsula, the southeastern peninsula and Pulau Buton, and Sulawesi's core (see tables 6 and 20). Each has been taken in the same trapline in three places: the PuroValley at Bakubakulu, 600 m, and the valley of the Sungai Miu along Sungai Oha Kecil at 290 m and Sungai Sadaunta at 675 (see the account of B. chrysocomus). Both species are also recorded from the southern end of the southwestern peninsula where the comparative material consists of subfossils and modern specimens representing B. andrewsi and subfossils only for B. chrysocomus; no modern examples of B. chrysocomus have been collected anywhere on the southwestern peninsula south of the Tempe Depression (identified in fig. 1). Identity of the subfossils and their comparisons with B. andrewsi and subfossil examples of B. chrysocomus are discussed in a later section (see Subfossils).

Bunomys chrysocomus is physically smaller than B. andrewsi, averaging less in lengths of head and body, hind foot, ear, and mass (tables 19, 41). The tail of B. chrysocomus is typically shorter than that of B. andrewsi (mean range of population samples  =  120.0–142.7 mm for B. chrysocomus, mean range  =  111.5–156.8 mm for B. andrewsi) but at the same time averages longer in relation to length of head and body (LT/LHB  =  84%–98% for B. chryscocomus, 75%–92% for B. andrewsi).

Bunomys chrysocomus and B. andrewsi are not easily separated by color of fur and appendages, particularly in those places where examples of each were taken in the same trapline. Texture and length of the fur covering upperparts of head and body is similar in the two species. The coat is dark brownish gray in most examples of B. chrysocomus and only lightly speckled (buffy bands of the hairs are dull and short) while the pelage of B. andrewsi is brighter with more intense buffy and yellowish speckling (buffy bands are bright and wide); ears and tops of the front and hind feet are similarly pigmented in both species. Some examples of B. chrysocomus—from Gunung Balease and Gunung Nokilalaki, for example—have very dark, brownish-black dorsal fur with muted speckling and are unlike nearly all examples of the brighter B. andrewsi (exceptions are the specimens from the Mamasa area that were trapped at 1500–1600 m and have much darker upperparts than is usual in most samples of B. andrewsi). Variation in color pattern of the tail is similar in the two species, a low percentage of specimens in samples of each have a white-tipped tail, and in both species that unpigmented segment is short relative to length of tail (table 8). Bunomys chrysocomus has longer, more gracile claws on the front feet.

While preserved specimens of each species can be difficult to distinguish, the living animals are easier: B. chrysocomus has a longer muzzle with an upturned snout in contrast to the broad face of B. andrewsi without an upturned rhinarium.

Sexually mature males can be separated by size of testes (table 9), which in B. chrysocomus are large relative to body size (mean length of testes/length of head and body  =  22%), but in B. andrewsi are relatively smaller (8%–15%). This relative size disparity is strikingly evident in freshly caught animals where sexually mature examples of each species are taken at the same place.

Configuration of spermatozoa is similar in the two species, but the sperm head is shorter and wider in B. andrewsi (Breed and Musser, 1991).

Bunomys chrysocomus has a small skull and weak molars compared with B. andrewsi. Univariate mean values for all cranial and dental variables in combined population samples of B. andrewsi exceed univariate means for those dimensions in all the combined samples of B. chrysocomus (table 42). Similar metric distinctions exist in samples of each species obtained from most places where the two are regionally sympatric (table 48). The dimensional contrasts can be appreciated in the images of skulls of B. chrysocomus arranged in figures 16 and 99–Fig. 100.101 with those of B. andrewsi portrayed in figures 52–Fig. 53.54 and 99–Fig. 100.101. Samples from the northern part of the west-central mountain block are an exception because the B. andrewsi from there are smaller in body size and the range of variation in some of the cranial variables overlaps in samples of the two species; this contrast will be amplified in a later section.

Morphometric distinctions between B. chrysocomus and samples of B. andrewsi are summarized by a scatter plot containing specimen scores projected onto first and second principal components where they form two oblique elliptical clouds, one representing B. chrysocomus, the other B. andrewsi (fig. 62, lower graph). Major axes of the elliptical spreads of scores are parallel, phenetically distinct: their Y-intercepts are significantly different between the two species (+0.873 versus −1.984; F  =  117.57, P  =  0.000), but their slopes are comparable (1.140 versus 1.075; F  =  0.20, P  =  0.652). Moderate to high positive loadings for nearly all variables (r  =  0.42–0.91; table 47) on the first component reflect size, scores representing B. andrewsi with the larger skulls and molars to the right, those for B. chrysocomus with the smaller skulls and molars to the left with overlap in the center of the scatter plot. Loadings for skull size (occipitonasal length and zygomatic breadth), length and breadth of the rostrum, size of braincase, breadth of zygomatic plate, lengths of diastema and the postpalatal region, expanse of the incisive foramina, and size of molars are especially influential in dispersing scores along the first axis. All these dimensions are less in B. chrysocomus (table 42), especially overall size of the skull, width of the zygomatic plate, size of the rostrum along with extent of the incisive foramina, and molar robustness, which form salient distinguishing landmarks readily appreciated in the images of skulls portrayed in the figures as well as in side-by-side comparisons of actual skulls.

Frequencies of a cusp and cusplet on lower molars differ between the two species (table 10). An anterior labial cusplet occurs on the first molar in half of the B. chrysocomus examined but is absent from all the specimens of B. andrewsi surveyed. The third molar bears an anterolabial cusp in 65% of the sample of B. chrysocomus but is present at a much lower frequency in the specimens of B. andrewsi (18% of the sample).

Bunomys andrewsi and B. coelestis: Bunomys coelestis inhabits montane forests on Gunung Lompobatang where samples were collected between 1800 and 2500 m; B. andrewsi is found in tropical lowland evergreen rainforest at lower elevations on the volcano with the only large sample coming from Lombasang at 1100 m; the species is also documented by subfossils excavated from deposits in caves on the western coastal plain. Bunomys andrewsi and B. coelestis are contrasted here because individuals in the peninsular population of B. andrewsi on average are smaller in body size than those in other geographic samples of the species, and many cranial dimensions, compared to samples of B. andrewsi from elsewhere on the island are more similar to B. coelestis (tables 49, 51).

Bunomys coelestis is physically larger than animals in the peninsular sample of B. andrewsi, a difference reflected in its greater univariate means for lengths of head and body, tail, hind foot, and ear (compare the values for B. coelestis listed in table 19 with those for the sample of B. andrewsi from Lombasang in table 41). Bunomys coelestis has darker upperparts, a longer muzzle, and appreciably longer claws at the ends of the front digits.

Compared with B. andrewsi from Lombasang, B. coelestis typically has a longer but narrower skull (indexed by occipitonasal length and zygomatic breadth); wider interorbit; longer but narrower rostrum (elongate compared with the relatively stocky rostrum of B. andrewsi); wider zygomatic plate; longer diastema, longer and wider bony palate, and longer basicranial region (measured by postpalatal length); less spacious incisive foramina (shorter and narrower than the expanded foramina in B. andrewsi); smaller auditory bulla; and smaller molars (table 49). Size of the braincase (breadth and height) is comparable in the two species.

These contrasts in cranial and dental dimensions indicated by univariate mean values are summarized in a scatter plot where individual specimen scores are projected onto first and second principal components (fig. 63, upper graph). Two widely separated groups of scores represent B. coelestis in the right half of the ordination and B. andrewsi from Lombasang in the left, positions influenced by the longer skull of B. coelestis along with its longer rostrum and diastema, and longer and wider bony palate (r  =  0.42–0.76; table 50). Moderate to high negative correlations (r  =  −0.40 to −0.88) point to the wider skull of B. andrewsi (indexed by zygomatic breadth) along with its broader rostrum and mesopterygoid fossa, longer and broader incisive foramina, larger bullae, and heavier molars as compared with B. coelestis, contrasts between the two species that are mirrored by univariate means (table 49).

Fig. 63.

Specimen scores representing two geographic samples of Bunomys andrewsi and samples of B. coelestis and B. prolatus projected onto first and second principal components extracted from principal-components analysis of 16 cranial and two dental log-transformed variables. Upper graph: the sample of B. andrewsi (empty circles; N  =  7) from Lombasang on the lower slopes of Gunung Lompobatang is contrasted with the sample of B. coelestis (filled diamonds; N  =  19) from montane forest higher on the same volcano. Lower graph: the lowland sample of B. andrewsi from Sungai Ranu (empty circles; N  =  5) at the western margin of the eastern peninsula is contrasted with the montane sample of B. prolatus from nearby Gunung Tambusisi (asterisks; N  =  8). See table 50 for correlations (loadings) of variables with extracted components and for percent variance explained for both ordinations.

Bunomys andrewsi and B. prolatus: Samples of three species of Bunomys come from Gunung Tambusisi and adjacent lowlands in the western region of the eastern peninsula of Sulawesi. Bunomys chrysocomus and B. prolatus were collected by C.H.S. Watts from slopes of the mountain (1372–1829 m), and he obtained B. andrewsi from adjacent lowland forest in the Sungai Ranu area (50 m). The large-bodied Bunomys prolatus could possibly be confused with B. andrewsi, which is also characterized by large body size in the Tambusisi region.

While B. prolatus and B. andrewsi are comparable in body size (estimated by length of head and body), B. prolatus has a much shorter tail (absolutely and relative to length of head and body), shorter hind feet, but relatively larger ears (compare the measurements of B. prolatus listed in table 18 with those of B. andrewsi from Kuala Navusu, Pinedapa, and Wawo + Masembo listed in table 41; I lack external measurements for the sample from Sungai Ranu). As is typical of the contrast between montane and lowland populations, the lush dorsal coat of B. prolatus is soft and dense, 20–25 mm long; that of most B. andrewsi, and especially the rats from Sungai Ranu, are harsher and 12–15 mm long. The robust and very long front claws of B. prolatus (fig. 36) are unlike the weaker and short front claws, a conformation typical of specimens in all population samples of B. andrewsi.

The skull of B. prolatus has a gracile aspect to it compared with the stocky conformation that is usual for B. andrewsi (compare the images of B. prolatus in figs. 37–Fig. 38.39 with those for B. andrewsi from Kuala Navusu portrayed in figs. 52–Fig. 53.54). The more delicate cranial conformation in B. prolatus, so visually apparent in the cranial illustrations, is reinforced qualitatively by univariate means for cranial and dental variables where most dimensions average less than those for the sample of B. andrewsi from Sungai Ranu; exceptions are interorbital breadth and length of bullar capsule, which average greater in B. prolatus (table 49).

Contrasts among the cranial and dental variables are summarized in multivariate space by the scatter plot of specimen scores projected onto first and second principal components (fig. 63, lower graph). Aggregations of scores identifying the specimens of B. prolatus and those for B. andrewsi from Sungai Ranu are widely separated along the first axis, reflecting the general disparity in size as indicated by the large and positive loadings (r  =  0.45–0.99; table 50) for all but two variables, which mirrors the contrasts in univariate means (table 49). The two high negative loadings are for interorbital breadth (−0.86) and length of bulla (−0.51), both absolutely and relatively greater in B. prolatus (table 49).

The long fur of B. prolatus, its robust and long front claws, elongate skull, wide interorbit, narrow zygomatic plate and mesopterygoid fossa, short and narrow incisive foramina, large bulla, and link to montane forest are strongly diagnostic compared with the larger-bodied B. andrewsi from the nearby lowlands.

Geographic Variation

There is conspicuous variation in body size among geographic samples of B. andrewsi. During 1974, I was trapping between 290 and 675 meters along the Sungai Oha Kecil, Sungai Miu, and Sungai Sadaunta in the northern part of the west-central region of Sulawesi and encountering mostly B. chrysocomus. Here and there another kind of rat showed up in the traps that in body size and fur color resembled B. chrysocomus but with a shorter muzzle. It was also similar to B. andrewsi but physically smaller than rats in samples of that species with which I was familiar. Later I worked in lowlands east of the west-central mountain block but not too distant from Pinedapa, the place where H.C. Raven collected a series of rats in 1918 that would subsequently be described by Miller and Hollister (1921a) as Rattus adspersus. Near my camp on Kuala Navusu, I caught what clearly looked to be adspersus. The rats resembled animals taken at the Sungai Oha Kecil, Sungai Miu, and Sungai Sadaunta (means for LHB  =  163.1 mm and weight  =  113.7 g for the Puro-Sungai Miu sample) but were larger in body size (LHB  =  177.4 mm and weight  =  154.6 for the sample from Kuala Navusu).

The difference registered by my two collections generally reflects the magnitude of variation in adult body size among all the samples of B. andrewsi I have studied (see table 41). Generally, large physical size characterizes specimens in the population samples from northeast–central core (Labuan Sore, Kuala Navusu, and Pinedapa), south–central core (Gunung Balease, Malili area, and Sukamaju), and the eastern + southeast peninsulas (Sungai Ranu, Wawo, and Masembo). Animals averaging smaller in body size form the population samples from lowlands and highlands in the west-central mountain block—northern west-central highlands (Puro-Sungai Miu, Tamalanti, and Tuare) and southern west-central highlands (Mamasa Area)—and the southwest peninsula (Lombasang).

To determine the geographic trends in body size, I relied on my measurements of cranial and dental dimensions (measurements for head and body and appendages were made by different collectors who may or may not have utilized the same endpoints). Morphometric relationships among the population samples are summarized in the univariate descriptive statistics listed in table 51, results of principal-components and discriminant-function analyses (figs. 64, 65), cluster diagram (fig. 66), and descriptive exposition in the text.

Fig. 64.

Specimen scores representing all seven population samples of Bunomys andrewsi projected onto first and second principal components extracted from principal-components analysis of 16 cranial and two dental log-transformed variables. Symbols: filled circles  =  northeast-central region (Labuan Sore, Kuala Navusu, and Pinedapa; N  =  32); empty circles  =  south-central region (Gunung Balease, Malili Area, and Sukamaju; N  =  16); empty triangles  =  eastern + southeast peninsula (Sungai Ranu, Wawo, and Masembo; N  =  9); filled inverted triangles  =  northern west-central region (Puro-Sungai Miu, Tamalanti, and Tuare; N  =  16); asterisks  =  southern west-central region (Mamasa Area; N  =  10); empty diamonds  =  southwest peninsula (Lombasang; N  =  7); stars  =  Pulau Buton (N  =  2). Polygons define limits of dispersion for scores in each population sample. Arrows point to scores for holotypes: andrewsi (star), adspersus (filled circle), heinrichi (empty diamond), and inferior (empty triangle). Correlations (loadings) of variables with extracted components and percent variance explained are listed in table 52.

Fig. 65.

Results of discriminant-function analysis of 16 cranial and two dental log-transformed variables derived from seven population samples of Bunomys andrewsi. Symbols: filled circles  =  northeast-central region (Labuan Sore, Kuala Navusu, and Pinedapa; N  =  32); empty circles  =  south-central region (Gunung Balease, Malili Area, and Sukamaju; N  =  16); empty triangles  =  eastern + southeast peninsula (Sungai Ranu, Wawo, and Masembo; N  =  9); filled inverted triangles  =  northern west-central region (Puro-Sungai Miu, Tamalanti, and Tuare; N  =  16); asterisks  =  southern west-central region (Mamasa Area; N  =  10); empty diamonds  =  southwest peninsula (Lombasang; N  =  7); stars  =  Pulau Buton (N  =  2). Arrows indicate scores for holotypes: andrewsi (star), adspersus (filled circle), heinrichi (empty diamond), and inferior (empty triangle). Upper graph: Specimen scores projected onto first and second canonical variates. Lower graph: Specimen scores projected onto second and fourth canonical variates. See table 53 for correlations (loadings) of variables with extracted canonical variates and for percent variance explained for both ordinations.

Fig. 66.

Pattern of phenetic relationships among population samples of Bunomys andrewsi based on UPGMA clustering of squared Mahalanobis distances among group centroids and derived from discriminant function-analysis using log-transformed values of 16 cranial and 2 dental variables.

Intersample variation in cranial and dental measurements is apparent in the ordination of specimen scores for all seven population samples of B. andrewsi projected on first and second principal components (fig. 64); embedded in the scatter plot are results concordant with geographic differences in body size I encountered in my trapping. Moderate to high positive loadings (r  =  0.46–0.95; table 52) among nearly all variables influence the dispersal of scores along the first axis; variation in size is stressed here with scores for the smallest skulls sprinkled to the left in the scatter plot, those for larger skulls to the right. Reflected in the spread of points along the first axis is individual variation and that attached to adults of different ages (young to old) but there is also a geographic pattern. Scores for specimens with the largest skulls are from eastern + southeast peninsulas (empty triangle; Sungai Ranu, Masembo, and Wawo) and cluster along the far right of the entire scatter. Northern west-central region (inverted filled triangle; Puro-Sungai Miu, Tamalanti, and Tuare) and southwest peninsula (empty diamond; Lombasang) are represented by scores filling the left half of the ordination, and these samples contain the smallest skulls (table 51). Straddling these outlying clumps are scores for specimens in northeast–central region (filled circle; Labuan Sore, Kuala Navusu, and Pinedapa), south–central region (empty circle; Gunung Balease, Malili area, and Sukamaju), and southern west-central region (asterisk; Mamasa Area). Of the two scores representing Pulau Buton, the very young adult aligns with the smaller specimens, the other—the old adult holotype—nests in the center of the cloud of scores for northeast–central region. Although there is a geographic trend in size of skulls, clusters representing the population samples greatly overlap and not one of them is isolated within the ordination.

Shape information can be extracted from the spread of scores along the second component (table 52). Most specimens from northeast-central region (filled circle in fig. 64) have a relatively narrower zygomatic plate, wider mesopterygoid fossa, larger bullae, and shorter molar row compared with animals represented by the points in the top half of the scatter plot, especially those from the west-central mountain block (northern west-central region and southern west-central region population samples).

A sharper picture of geographic trends in intersample variation of cranial and dental variables emerged from results of discriminant-function analysis. Among the first, second, and fourth canonical variates extracted, the spread of scores along the first variate (fig. 65, upper graph) is a response to the positive moderate to high correlations (or loadings; r  =  0.32–0.68; table 53) for the variabes. Size is reflected along this axis: the right half of the ordination contains samples from the west-central mountain block (northern west-central region and southern west-central region) and southwest peninsula, which are generally characterized by small skulls; the left half holds scores for larger-bodied animals from eastern + southeast peninsulas and northeast–central region (east of the west-central mountain block); scores for samples from south–central region overlap the groups of scores in the left and right halves of the scatter plot. Points representing the two specimens from Pulau Buton align with those representing animals with larger skulls. The high positive loadings for overall size of skull (occipitonasal length and zygomatic breadth), breadth of braincase and zygomatic plate, length of diastema, postpalatal length, breadth of bony palate, expanse of incisive foramina, and length of molar row indicate that these dimensions are not as great in samples from the west-central mountain block and Lombasang on the southwestern peninsula compared with series from elsewhere in Sulawesi, mainly those landscapes east of the west-central mountain block.

Shape differences are indicated by the spread of scores along the second variate in the upper graph in figure 65. High positive loadings for nearly all variables (r  =  0.27–0.69; table 53), along with isolation of the scores for eastern + southeast peninsulas (empty triangle) on the right margin of the ordination, and southwest peninsula (empty diamond) at the left extreme, point to the relatively overall larger cranial and dental dimensions in the former and relatively smaller dimensions in the latter compared to the other four samples clumped together in the center of the ordination, which includes the holotype of andrewsi (star).

The lower scatter plot in figure 65 reveals a pattern of covariation in cranial and dental measurements among the population samples similar to that in the upper scatter plot of figure 65. The large and positive loadings for breadth of rostrum (0.45) and length of bulla (0.69) on the fourth variate (see table 53) isolate scores for the two specimens from Pulau Buton from those points signifying specimens in all the other population samples. Compared with the six population samples, whether they contain small, large, or skulls of intermediate size, animals in the sample from Pulau Buton have a relatively wider rostrum and much larger tympanic bulla, particularly the holotype of andrewsi. A large bulla is characteristic of the small sample from Pulau Buton: 7.2 mm is the mean length of bulla for Pulau Buton, and 6.3–6.8 mm is the range of means for the other six population samples.

Cluster analysis based on squared Mahalanobis distances results in the pattern of phenetic relationships among the seven population samples portrayed in figure 66. Two primary groups of samples are apparent. The largest unites all samples from mainland Sulawesi except those at the most southern margins of the island, Pulau Buton off the south coast of the southeastern peninsula and Lombasang at the southern end of the southwestern peninsula, which form a group discrete from that containing the other five population samples.

Within the larger assemblage, the phenetic relationships among samples generally mirror geography. Specimens from lowlands at Labuan Sore, Kuala Navusu, and Pinedapa (northeast-central region) link with animals from Gunung Balease, the Malili area, and Sukamaju (south-central region), all localities east or at the margin of the west-central mountain block. Samples from the northern and southern parts of the west-central mountain block are united in the diagram and are linked (between 30 and 40 distance units) to the previous two samples from east of that mountainous region. These two sets join the sample of animals from the west end of the eastern peninsula at Sungai Ranu and Wawo and Masembo in the lowlands adjacent to Pengunungan Mekongga on the southeastern peninsula. All these samples describe a distribution covering the core of Sulawesi and the southeastern peninsula. The trend in skull size (and generally body size) extends from the west-central mountain block where populations are characterized by small skulls on average to east of the mountain block where larger-bodied animals predominate, with the largest skulls in the samples from Sungai Ranu and the southeastern peninsula. The names “Rattus adspersus” (Miller and Hollister, 1921a), based on the series collected at Pinedapa, and “Rattus penitus inferior” (Tate and Archbold, 1935a), applied to specimens from Masembo and Wawo, are associated with this large geographic block of samples.

Other traits I examined on specimens in the five population samples do not show patterns of intersample variation that accords with the geographic trend in size associated with cranial and dental variables. For example, I did not detect any geographic variation in qualitative traits of the skull or teeth. And with few exceptions, all the adults have a moderately soft and long dorsal coat that is dark brown or brownish gray speckled with buff and black; in any large sample, the ventral coat ranges from pale grayish white or pale grayish buff to dark grayish white, dark grayish buff, buffy gray, or ochraceous-gray (some specimens show rusty patches); ears are brown or brownish gray; dorsal surfaces of feet are white, gray, or buffy; the tail is shorter than combined length of head and body (LT/LHB  =  85%–92%), brownish over the dorsal surface, white, mottled, or brown on the ventral surface, and either lacks or shows a relatively short white tip (see table 8).

There is variation in thickness and color of fur covering head and body that corresponds to differences in elevation, which is illustrated by samples from two regions. Specimens in the Mamasa area (the southern part of the west-central mountain block) come from higher elevations (900–1600 m) than do most examples of B. andrewsi and have a thicker dorsal coat (15–20 mm) that is much darker than lowland samples. Underparts also average darker, ranging from dark grayish white to dark grayish buff.

The population sample of the south-central region contains specimens collected between 830 and 925 m on Gunung Balease and those obtained at 450 m in the Malili area, approximately 80 km southeast of Gunung Balease, that cannot be distinguished by cytochrome-b sequences (molecular trees passed to me by J.L. Patton and K.C. Rowe, in. litt., 2011), body size, cranial and dental traits, or pelage thickness. They do show, however, slight differences in coat color that is related to elevation. Specimens from Gunung Balease have darker upperparts (dark brown to brownish black speckled with buff) than do the rats in the sample from the Malili region, which in pelage color is closely similar to the specimens from Pinedapa and Kuala Navusu and others from 400 m and lower (rich brown speckled with buff over the upperparts). Underparts of both the Balease and Malili specimens range from grayish white to grayish buff (the buff forms either a pale or intense wash over the underparts), but the mountain animals are slightly darker.

The two examples from Pulau Buton, which comprise the type series of “Mus andrewsi” (Allen, 1911) are distinguished from all other samples primarily by their relatively large ectotympanic bullae, slightly shorter but wider rostrum, short incisive foramina, and slightly average smaller skull. They also have very short tails in relation to head and body (LT/LHB  =  75%; 85%–92% is the range for the other geographic samples). Color of the fur and appendages closely resembles samples from farther north in the lowlands, Kuala Navusu, Pinedapa, and the Malili area, for example. It is their average smaller skull that may be most responsible for linking the two specimens with the sample from Lombasang at the southern end of the southwestern peninsula, the type series of “Rattus penitus henrichi” (Tate and Archbold, 1935a); otherwise the animals in each sample are quite different. The Lombasang rats were collected at 1000 m and have a thicker coat (15–20 mm thick as opposed to 12–15 mm for the Buton specimens from the lowlands) that is a richer and brighter brown, a relatively longer rostrum, longer incisive foramina (absolutely and relative to skull length), and smaller bullae (relative size is similar to specimens in samples from the center of the island and southeastern peninsula. Also, a small cusp t3 occurs on the second upper molar in 78% of the Lombasang sample; the young adult from Pulau Buton lacks a comparable cusp (molars are too worn to determine presence or absence of cusp t3 on the other Buton specimen).

To summarize, I provisionally regard the variation in coat color, body size, and the cranial and dental measurements described above to be contained within the phenetic boundary of a single species. Here are highlights of this hypothesis and suggestions for future inquiry:

Fig. 67.

Dorsal (top) and ventral (bottom) views of adult skulls representing separate population samples of Bunomys andrewsi. Left to right: Pulau Buton (USNM 175899, holotype of andrewsi), off the tip of the southeastern peninsula); Kuala Navusu (AMNH 225652), Sulawesi's core (skull is morphometrically similar to the holotypes for adspersus and inferior); and Lombasang (AMNH 101006, holotype of heinrichi), southwestern peninsula. ×2.

Natural History

Included here is a summary of information covering habitat and diet, along with my few observations of nest construction.

Habitat: Bunomys andrewsi has been collected in primary forest, secondary growth, and village gardens. Along the Sungai Oha Kecil and Sungai Sadaunta in the northern part of the west-central region, and in the Kuala Navusu area, my helpers and I trapped B. andrewsi in primary forest along streams and on hillsides—all sites were shaded where the ground remained either damp or wet (descriptions of trap sites are summarized in table 54). Mean ambient air temperature ranged from 66.9° to 78.8° F along Sungai Oha Kecil and Sungai Sadaunta, and 73.6° to 80.9° F at Kuala Navusu, with relative humidities reaching 100% in all three places (table 3). Individuals were caught in traps placed on decaying tree trunks and limbs spanning streams and ravines; in runways beneath trunks and limbs that are remnants of treefalls lying on the forest floor, on wet stream terraces covered by shrubs, small trees and canopied by taller streamside forest; beneath moss-covered rocks on wet hillsides, and beneath roots of living trees. Decaying tree-falls were especially productive places to set traps because they provided excellent cover for runs beneath the trunks and limbs and are usually shaded by a dense cover of shrubs, ferns, rattan rosettes, and saplings that offered a constant damp or wet microenvironment. Examples of the typical places where we caught B. andrewsi are presented in figures 68 and 69. We did not encounter the rats in forest high on steep hillsides or ridgetops, areas that dry out faster than protected hillsides above streams and stream banks and terraces, which remain wet.

Fig. 68.

Tropical lowland evergreen rain forest (in 1975) at Kuala Navusu (30 m) where in addition to Bunomys andersoni, we trapped Maxomys hellwaldii, Rattus hoffmanni, Paruromys dominator, and Echiothrix centrosa. Usma is siting at the base of a Heritiera javanica, one of the several species of large and magnificent old-growth trees that emerge above the upper canopy. We collected samples of about 160 species of trees in the Kuala Navusu area as well as woody shrubs and vines, monocots, bananas, cycads, seven kinds of palms, and eight species of rattans.

Fig. 69.

Decaying trunk lying in dense understory on stream terrace in tropical lowland evergreen rain forest at Kuala Navusu, 46 m (in 1975). Bunomys andrewsi, Maxomys hellwaldii, and Echiothrix centrosa were caught in traps placed in a runway beneath the trunk (see habitat description for AMNH 225665 in table 54). Taeromys celebensis was taken nearby on an old treefall spanning the stream.

Bunomys andrewsi has also been obtained in habitats where the original forest has been altered by human activity. The samples from Gunung Balease and the Malili area (Desa Lawaki Jaya) were trapped in secondary forest (J.L. Patton, personal commun., 2011). At Omu, a village at the lower end of my transect, a rat was “taken in a garden at edge of a swampy area (notation on the skin tag). In the Mamasa area, B. andrewsi was commonly encountered in second-growth forest and cacao gardens (K.C. Rowe, in litt., 2012).

We never trapped examples of B. andrewsi on woody vines above ground or in trees. It, like other species of Bunomys, is terrestrial and active during the night.

Diet: Bunomys andrewsi consumes a variety of invertebrates, vertebrates, and fruit, but not fungi; the categories and range of items in each are similar to those constituting the diet of B. chrysocomus (see that account and table 13). My dietary records derive from feeding three captive B. andrewsi collected at Kuala Navusu (two adults and a juvenile) and study of samples from stomachs of animals captured at Kuala Navusu, along my transect in the west-central region (Sungai, Oha Kecil, Sungai Miu, and Sungai Sadaunta), and specimens from Gunung Balease and the Malili area (obtained by J.L. Patton, K.C. Rowe, and J.A. Esselstyn); see tables 54 and 55.

All three captives aggressively attacked and consumed invertebrates. Each would instantly grab the offered earthworm or insect from my fingers, scamper to an opposite corner of the cage with the prey in its mouth, stop and watch me for a few seconds, then turn its back to me and begin eating. Even flies were chased about the cage. If a rat was eating fruit and offered an insect, the fruit was instantly dropped and the insect yanked from my fingers.

Items constituting the diet of B. andrewsi are summarized below.

Earthworms—Captives grabbed earthworms from my fingers and consumed them in less than a minute, handling the worms in the same fashion as described for B. chrysocomus. Cut segments of earthworms were found in stomachs of other B. andrewsi (tables 54, 55).

Snails—When the three captives were offered snails (half-inch to an inch in diameter), they unhesitatingly began to process them. Each rat held the shell in its front paws, made an opening with its incisors and then extracted the snail's body, all of which was consumed. The behavior was similar to that I described for B. chrysocomus (see that account).

Insects and other arthropods—Captives were offered moths, two kinds of large crickets (3 inches long), grasshoppers, praying mantises, several kinds of adult beetles, and large beetle larvae found in dry and rotting wood. All were quickly accepted and eaten, the behavior with these prey items was very similar to that described for B. chrysocomus. Contents of stomachs included rhinotermitid termites, adult ants and ant pupal cases, a variety of adult and larval beetles (including legless and cursorial larvae), macrolepidopteran larvae, and geophilomorph centipedes (tables 54, 55). Rhinotermitid termites were the most common insect found in stomachs, 18 of 42 stomachs contained these insects (I omitted stomachs that were empty or contained only bait); the stomach of a rat collected at Kuala Navusu was crammed with worker and soldier rhinotermitid termites and contained no other invertebrates and no fruit.

The stomach contents of a rat collected on Gunung Balease illustrates the kinds of insects procured by B. andrewsi. The stomach was full, containing a few macrolepidopteran larval skins, many remains of rhinotermitid termites (head capsules, legs, abdomens), at least one large cursorial beetle larva (about 2 inches long) chewed into pieces, internal tissue and sclerites of smaller legless beetle larvae, a few very small intact legless beetle larvae, a few ants, and a bit of unidentified blackish debris.

Other invertebrates—I gave an adult male a small land crab, which he quickly accepted, used his front feet to manipulate the crab, bit the carapace in several places, but then rejected it, and showed no further interest.

Vertebrates—I did not find vertebrate remains in the stomachs examined, but two of the captives readily accepted and consumed geckos. The largest offered was about 7 inches long, 4 inches of which were head and body. I held it by the body and presented it to an adult male who instantly grabbed the gecko by the head and pulled it out of my fingers. He bit the head, chest, and abdomen several times and then manipulated the lizard until its head was between the front paws and then in his mouth. By this time the tail had come away from the body and the gecko was immobile. The rat began eating from the nose back toward the rump. Occasionally the lizard jerked, but the rat quickly placed a hind foot on the lizard's pelvis to stabilize the gecko as it chewed on the other end. Once, the rat turned the gecko's body around and ate from the rump for a bit, then returned to the head, finally consuming the entire body; the detached tail was also eaten. The process took just a few minutes and only a few pieces of breast bone remained on the cage floor. It was clear the rat recognized the gecko as prey and did not hesitate to attack and eat it. Another rat ate a smaller gecko in much the same fashion. I found the geckos inside decaying tree limbs lying on the forest floor, the same kinds of rotting wood that provides habitat for cerambycid beetle adults and larvae, rhinotermitid termites, and ant pupae, as I described in the account of B. chrysocomus.

Fruit—Different fruits offered the three captives were unambiguously accepted or rejected. Figs—whether from tall canopy-forming strangler Ficus, other nonstrangler species that contributed to the canopy, or understory species—were accepted and readily consumed by all the captives. Figs are one of the most common of the identifiable fruit remains found in contents of stomachs (tables 54, 55). Also accepted and eatern were fruit from understory palms (Pinanga sp.); from the trees Sandoricum sp., Sapium sp., Palaquium obtusifolium, and another unidentified member of Sapotaceae; large seeds from the tree Hydnocarpus sumatrana; fruit from the vine Gnetum cuspidatum; and fruit from Pandanus.

The captives ignored the dark green fruit from Matthaea sanata, a shrubby tree growing in understory; from the nutmegs, Knema sp. and Myristica sp.; the citruslike fruit from the understory tree Dillenia serrata; large, hard nuts from fruit of the understory tree, Pangium edule; and the large, green fruits from the understory tree, Kjellbergiodendron celebicum.

Rarely did a stomach contain only fruit. For example, one rat from Gunung Balease had a stomach full of mostly pulp and tiny seeds from figs as well as pulp and hard thin skin from one other kind of fruit. Many fragments of rhinotermitid termites, small macrolepidopteran larval skins, several segments of an earthworm, and legs and sclerites from small adult beetles were mixed with the fruit remains.

Fungi—The ear fungus Auricularia delicata (called “karoko” by the local people) and a few kinds of jelly fungi were broken into pieces by all three of the captives, but the fragments were eventually dropped to the cage floor and ignored. I did not find macroscopic remains of fungi in any of the stomachs examined.

Overview—Like B. chrysocomus (see that account), B. andrewsi consumes fruit, mostly figs, disdains fungi, and is an aggressive predator of invertebrates and small vertebrates. Near camp on the Kuala Navusu, my helpers and I searched for places on the forest floor where B. andrewsi would find invertebrates. We first looked to earthworms. During the night after a rain we found earthworms scattered on the ground surface, beneath leaf litter, or in pools of water near the stream. During the day we located them in rotting sections of tree trunks and limbs or in the soil beneath. We also found burrows, each marked by a pile of processed soil, some as tall as 2 inches. Several small worms might occupy a single burrow and were found 2–6 inches below ground. Burrows were always on well-drained slopes or stream terraces. Because the earthworms are spotty in their distribution, it is difficult to provide any meaningful estimate of worms available to B. andrewsi per unit area. We did find one place on a steep hillside above a wet ravine where a piece of wood had decayed into slivers. The soil was stable. We collected 21 earthworms (8 g total) in a square meter; all occurred throughout the soil from from near the surface to a depth of 6 inches.

The most common site for both large and small worms was within and beneath rotting trunks and limbs from old treefalls. At a certain stage of decomposition the wood becomes soft and is mixed at soil level with a gray or bluish gray dense claylike layer; the worms are in this layer, and in passages within the wet and rotting pulpy wood.

Decaying sections of old treefalls lying on the forest floor also provide habitat for a variety of invertebrates in addition to earthworms that are sought and eaten by B. andrewsi. I tore apart a long section of rotting trunk (15 ft long, 10–12 inches in diameter) lying on a terrace about 30 ft above a stream. The pulpy wood was saturated with water in places and the underlying claylike layer nearly liquefied. Pigs had torn into the wood in two places. I extracted 30 grams of invertebrates (excluding termites—the terrestrial rhinotermitid termites, I presume—that infested the entire trunk and were too numerous to collect and weigh): 21 earthworms (some large, up to 5 inches long, most smaller, 2–3 inches), 3 mole crickets, and 6 small adult and nymphal cockroaches. From different and drier decaying trunks, I extracted scorpions, two kinds of diplopods (millipedes), several kinds of chilopods (centipedes), large adult and larval beetles, a gecko, and a legless lizard.

Small frogs and snails seemed to be most prevalent on the banks and terraces bordering streams. I found snails on top of the leaf litter and just above ground on stems of shrubs and ferns.

Nests: I placed dry leaves in the cages of two adults and a juvenile. Each formed a pile of leaves, then burrowed into the side, and came out at the top of the pile. During the day the rat slept in the top of the pile nearly concealed on all sides by the leaves. After a few days the leaves became compacted and each rat would shift them around until they again formed a deep cup-shaped sleeping chamber.

I assume that B. andrewsi lives in underground burrows. Near Kuala Navusu one rat was caught in a trap placed at the mouth of a burrow partially concealed by rocks on a hillside.

Ectoparasites, Pseudoscorpions, and Endoparasites

Sucking lice, ticks, and mites are the ectoparasites recorded to date from Bunomys andrewsi (table 14). An undescribed species of Hoplopura (Anoplura) is unique to B. andrewsi (Durden and Musser, ms.).

Immatures of the ticks, Dermacentor sp. and Haemaphysalis sp. (Acari, Ixodidae), have also been collected from a variety of hosts in addition to B. andrewsi: shrews (the endemic Crocidura elongata, and the commensal Suncus murinus), rusa (Rusa timorensis, nonnative), three endemic squirrels (Rubrisciurus rubriventer, Hyosciurus heinrichi and H. ileile), 10 other species of endemic murid rodents (Bunomys fratrorum and B. chrysocomus; Echiothrix centrosa; Maxomys hellwaldii, M. musschenbroekii, and M. wattsi; Paruromys dominator; Taeromys sp.; Rattus hoffmanni and R. facetus [recorded as R. marmosurus]), and three nonnative Rattus tanezumi (recorded as R. rattus), R. argentiventer, and R. exulans (Durden et al., 2008; L.A. Durden, personal commun.). Two species of mites in the genus Laelaps (Acari, Laelapidae) have been documented from Bunomys andrewsi (Van Peenen et al., 1974).

Chiridiochernes platypalpus is a pseudoscorpion described from B. andrewsi that was trapped at the base of Gunung Lompobatang on the southwestern peninsula (Muchmore, 1972).

Two kinds of endoparasites are known infect B. andrewsi. Host specimens from the Mamasa region were found to be parasitized by the nematode Bunomystrongylus miyagii (Trichostrongylina, Heligmonellidae), which is host-specific (Hasegawa and Mngali, 1996). Bunomys andrewsi is also a host for a species of liver fluke, Platynosomoides, which was also recovered from the nonnative Rattus tanezumi (Van Peenen et al., 1974).

Synonyms

Three scientific names prove to by synonyms of Bunomys andrewsi. Data attached to the holotype and type locality, description of the taxon as originally published, and reasons for its inclusion in B. andrewsi are presented below, ordered by publication date.

Rattus adspersus Miller and Hollister, 1921a: 71. HOLOTYPE: USNM 219602, an adult male (skin and skull; measurements are listed in table 40) collected January 22, 1918, by H.C. Raven (original number 3427). TYPE LOCALITY: Indonesia, Sulawesi, Propinsi Sulawesi Tengah, Pinedapa (01°25′S, 120°35′N), 100 ft (30 m; locality 3 in the gazetteer and on the map in fig. 50), northeastern margin of the central core.

Miller and Hollister (1921a:71) diagnosed Rattus adspersus as:

The specimens of adspersus, remarked Miller and Hollister (1921a: 72),

Miller and Hollister identified as adspersus 23 specimens from Pinedapa and two from Tuare. Three additional examples are from Labuan Sore (see locality 1 in the gazetteer), one had originally been determined to be Rattus rallus by Miller and Hollister, the other two as Rattus hoffmanni. Their adspersus is unquestionably phenetically distinct from the samples collected by Raven from the northeastern peninsula that Miller and Hollister thought were B. chrysocomus but are actually B. fratrorum. The holotype of andrewsi resides in USNM and was handy for comparison. While Miller and Hollister recognized a link between adspersus and andrewsi in coloration of the dorsal pelage, they presumbably did not think the resemblance indicated attributes of a single species, which is my hypothesis based on analyses of morphometric traits as well as chromatic aspects of the pelage.

Miller and Hollister's reference of adspersus to a “chrysocomus group” was reaffirmed strongly by Tate (1936: 554) when remarking on the holotype of adspersus he wrote that “The skull of this form unquestionably indicates its affinity to the chrysocomus group.” Between 1936 and 1969, adspersus retained its status as a species of Rattus in, first, a Rattus chrysocomus group (Ellerman, 1941), then a Rattus coelestis group (Ellerman, 1949), in subgenus Rattus (Laurie and Hill, 1954), and finally in subgenus Bullimus of Rattus (Misonne, 1969). Except for chrysocomus, fratrorum, colestis, koka, and andrewsi, Ellerman (1949) and Laurie and Hill (1954) relegated all the other taxa that had been associated with a Rattus chrysocomus group to subspecies of R. adspersus (see table 4).

Rattus penitus inferior Tate and Archbold, 1935a: 6. HOLOTYPE: AMNH 101059 (skin and skull; measurements are listed in table 40), an adult male collected January 23, 1932, by G. Heinrich (original nuber 808). TYPE LOCALITY: Indonesia, Propinsi Sulawesi Tenggara (southeastern peninsula of Sulawesi), Wawo (03°41′S/121°02′E), 50 m (locality 21 in gazetteer and on the map in fig. 50).

Rattus penitus inferior was characterized by Tate and Archbold (1935a: 6) as “A large member of the chrysocomus group with coarser pelage than either penitus penitus or penitus sericatus. Under parts irregularly suffused with hazel. Skull massive for the group, with long, broad palatal foramina.” They then provided a description of the holotype:

Their description of inferior was based on the holotype and nine additional specimens from southeastern Sulawesi (see localities 16 and 17 in the gazetteer and on the map in fig. 50). Both Tate (1936) and Ellerman (1941) treated inferior as a subspecies of Rattus penitus, Sody (1941) associated inferior with penitus but arranged the latter as a species of Frateromys, and later Ellerman (1949) treated inferior as a subspecies of Rattus adspersus, a link accepted by Laurie and Hill (1954). By the early 1990s, inferior was subsumed under Bunomys andrewsi (Corbet and Hill, 1992) where it has remained (Musser and Carleton, 1993, 2005; see table 4). See the preceeding section on Comparisons where the identity of the holotype of inferior as a sample of B. andrewsi and not B. penitus is demonstrated.

Rattus penitus heinrichi Tate and Archbold, 1935a: 6. HOLOTYPE: AMNH 101006 (skin and skull; measurements are listed in table 40), an adult male collected August 31, 1931, by G. Heinrich (original number 365). TYPE LOCALITY: Indonesia, Propinsi Sulawesi Tengah, Lombasang (05°16′S, 119°55′E), 1100 m (locality 25 in the gazetteer and on the map in fig. 50), in the foothills of Gunung Lompobatang, southwestern peninsula of Sulawesi.

Rattus penitus heinrichi was characterized by Tate and Archbold (1935a: 6) as “A medium-sized member of the chrysocomus group with dense though rather crisp pelage.” The holotype was described as follows:

Twenty-one specimens from Lombasang (locality 25 in gazetteer), in addition to the holotype, were identified as heinrichi.

After its description, heinrichi remained a subspecies of Rattus penitus in synoptic works published during the late 1930s and early 1940s (Tate, 1936; Ellerman, 1941); was transferred to Frateromys, its identity intact as a subspecies of penitus, by Sody (1941); and later arranged as a subspecies of Rattus adspersus by Ellerman (1949) and Laurie and Hill (1954). During the 1990s, Corbet and Hill (1992) and Musser and Carleton (1993) recognized heinrichi as a separate species, but by the next decade it lost its identity under Bunomys andrewsi (Musser and Carleton, 2005) where it currently remains (table 4). Why heinrichi is a peninsular population of B. andrewsi and not a subspecies of B. penitus is discussed in the preceeding section covering Comparisons.

Subfossils

Two maxillary fragments, three pieces of dentaries, and an incisor fragment are the subfossils representing B. andrewsi that have been found in caves on the southwestern peninsula of Sulawesi.

Two maxillary fragments, two pieces of dentaries, and an isolated segment of incisor (figs. 70, 71; tables 56, 57) were excavated from a shallow deposit forming the floor of a small rock shelter, Batu Edjaja II, that has been described by Mulvaney and Soejono (1970; 167, plate V; also see locality 26 in the gazetter and on the map in fig. 50). A few artifacts were recovered (geometric microliths and pottery shards), but the deposit had been so disturbed that no reliable age could be attached to them or to the rodent remains. A sample of charcoal from near the bottom of the deposit was determined to be “modern” by C-14 dating. David Bulbeck (in litt., 1997) informed me that “Batu Ejaya 2 has abundant geometric microliths suggesting some occupation by at least 3000–2000 b.p., but the basal radiocarbon date is modern and the deposits are obviously disturbed comprehensively” (also see Bulbeck, 2004; Simons and Bulbeck, 2004).

Fig. 70.

Subfossil maxillary fragments (×10) of Bunomys andrewsi excavated from Batu Ejaya II, a cave at the southern tip of the southwestern peninsula of Sulawesi (see gazetteer and the map in fig. 50). Upper image: AMNH 266963 (arrow points to small cusp t3 on the second molar, which is also found in 78% of the modern sample from the southwestern peninsula; table 10). Lower image: AMNH 265015. Measurements and descriptive information are provided in the text and tables 56 and 57.

Fig. 71.

Subfossil mandibular fragments of Bunomys andrewsi. Upper image: right dentary (×3) and first molar (×10) of AMNH 265014. Middle: left dentary (×3) and intact molar row (×10) of AMNH 265013. Both specimens were excavated from Batu Ejaya II, a cave at the southern tip of the southwestern peninsula of Sulawesi (see gazetteer and the map in fig. 50). Lower image: the right dentary (AMNH 266974; ×3) from Ulu Leang I, a cave about 40 km northeast of Ujung Pandang in the Maros region near the tip of Sulawesi's southwestern peninsula (see gazetteer and the map in fig. 50). Measurements and descriptive information are provided in the text and tables 56 and 57.

One right dentary fragment lacking molars (fig. 71; tables 56, 57) was recovered from sediments excavated at Ulu Leang I, a cave in the Maros region of the southwestern peninsula (locality 24 in the gazetteer and on the map in fig. 50; also see the map of archaeological sites in Simons and Bulbeck, 2004: 168). Excavations in the cave were described by Glover (1976), who also provided me with 8785 ± 45 years b.p. as the date of the horizon (layer V) in which the piece was located (Glover, personal commun.); a different assessment by Bulbeck (2004: 132) gives around 7500 b.p. for layer V. Specimens of B. chrysocomus were found in sediments from the same cave (see account of that species).

I compared all these subfossil fragments with modern samples of B. chrysocomus from Sadaunta in the west-central region of Sulawesi (no modern samples of B. chrysocomus are available from the southwestern peninsula), with a modern series of B. andrewsi collected at Lombasang on the lower flank of Gunung Lompobatang on the southwestern peninsula, and with a sample of B. coelestis from montane forest on Gunung Lompobatang. Whether maxillary fragments with upper molars, dentary fragments with or without molars, or isolated incisor, all are larger than their counterparts in the samples of B. chrysocomus and B. coelestis and share conformation and tooth size with the specimens of B. andrewsi (table 57).

One dentary fragment I determine to be B. andrewsi has a complete molar row from which measurements of the individual molars could be obtained as well as crown and alveolar lengths of the molar row. I used these measurements, and those from comparable dimensions in the modern samples of B. chrysocomus, B. coelestis, and B. andrewsi, in a principal-components analysis to test my identity gleaned from side-by-side comparisons of specimens. The resulting specimen scores projected on first and second principal components associate the score for the subfossil with the sample of B. andrewsi from Lombasang (fig. 72). The high positive correlations (r  =  0.84–0.96; table 58) among variables points to size as the primary factor spreading the scores along the first axis with those representing B. chrysocomus and B. coelestis with the smaller molars filling the left side of the scatter plot and those for B. andrewsi possessing heavier molars situated on the right. A similar pattern emerged when fewer measurements were employed in principal-components analyses using the same modern samples of B. chrysocomus and B. andrewsi, the same subfossil of B. andrewsi, and two subfossils of B. chrysocomus collected at Ulu Leang I (see the account of B. chrysocomus, fig. 35, and table 30).

Fig. 72.

Specimen scores representing Bunomys chrysocomus from Sungai Sadaunta in the northern part of the west-central region (filled triangles; N  =  20), B. coelestis from Gunung Lompobatang at the southern end of the southwestern peninsula (empty diamonds; N  =  20), B. andrewsi from Lombasang on the lower slopes of Gunung Lompobatang (empty circles; N  =  18), and a subfossil from Batu Ejaya II (asterisk; AMNH 265013) projected onto first and second principal components extracted from principal-components analysis of five mandibular molar log-transformed variables. The factor score for the subfossil from Batu Ejaya II is closely associated with the aggregation of points representing B. andrewsi, not B. chrysocomus or B. coelestis. See table 58 for correlations (loadings) of variables with extracted components and for percent variance explained.

One dental feature deserves mention. Cusp t3 occurs on the second upper molar in 78% of 18 modern specimens representing B. andrewsi collected at Lombasang. Within the sample the structure ranges in size from a tiny obscure bump to a large cusp defining the anterolingual border of the molar. Subfossil AMNH 269963 also has a small cusp t3 on the second upper molar. In the sample of B. andrewsi from Sulawesi's core and the southeastern peninsula, cusp t3 occurs on the second molar in only 17% of 70 specimens, and in 17% of 197 examples of B. chrysocomus from the west-central mountain block (table 10).

The next account describes a strictly montane species of Bunomys recorded from the west-central mountain block in the central core of Sulawesi and Pegunungan Mekongga on the southeastern peninsula.

Bunomys penitus (Miller and Hollister, 1921)

Rattus penitus Miller and Hollister, 1921a: 72.

Rattus sericatus Miller and Hollister, 1921a: 73.

Holotype

USNM 218686, the skin and skull of an adult male (original number 3109) collected January 21, 1917, by H.C. Raven. Measurements (external, cranial, and dental) and other relevant data are listed in table 40. The stuffed skin is an intact standard museum preparation. Both cranium and mandible are complete, all incisors and molars are present (fig. 73).

Fig. 73.

The holotype of Bunomys penitus (USNM 218686), an adult male from Gunung Lehio, 1829 m, in the northern portion of the west-central mountain block of Sulawesi. ×2.

Type Locality

Gunung Lehio (01°33′S, 119°43′E), 6000 ft (1830 m; locality 40 in the gazetteer and on the map in fig. 51), west-central mountain block, Propinsi Sulawesi Tengah, Indonesia.

Emended Diagnosis

Among the largest in physical size (LHB  =  155–242 mm, WT  =  95–170 g, ONL  =  39.3–46.1 mm) of the species in Bunomys and further characterized by the following combination of traits: (1) a long muzzle, broad head, and stocky body; (2) dorsal fur thick, lustrous, brownish gray speckled with buff, ventral fur grayish white, digits white, dorsal carpal and metacarpal surfaces typically white, ranging from grayish white to grayish brown in some samples; (3) claws on front feet short and somewhat delicate, long ungual tufts forming dense cover over front and hind claws; (4) tail shorter or slightly longer than length of head plus body (LT/LHB  =  88%–102%), dark glossy gray to brownish gray on the dorsal surface, glossy white on the ventral surface (5) white tail tip common (98% of 293 specimens) and when present is long relative to tail length (mean  =  21.0%, range  =  3%–68%); (6) testes small relative to body size (range  =  9%–13%); (7) shape of sperm head similar to that of B. chrysocomus but slightly wider with a shorter apical hook and spermatozoan tail; (8) robust skull with a long and wide rostrum, narrow and sloping zygomatic plate, long bony palate and incisive foramina, and large ectotympanic bulla relative to skull size; (9) molars large relative to size of skull and mandible; (10) large labial cusplet sits next to or partially merged with cusp t6 in 30% of sample, cusp t3 occurs frequently on second upper molar (62%) but not on third molar (5%); (11) anterolabial cusp present on second lower molar in about half of sample but absent from third lower molar; (12) anterior labial cusplets typically infrequent on first lower molars (8%), posterior labial cusplets typically present on first and second molars in all or most of sample (97%–100%); and (12) karyotype, 2N  =  42, FNa  =  58, FNt  =  60 (females) or 61 (males).

Geographic and Elevational Distributions

Samples of Bunomys penitus come from two major mountainous regions (see gazetteer, the map in fig. 50, and table 5). Most specimens have been collected from the west-central mountain block in Sulawesi's core where they were taken on ridges and peaks covered by lower and upper montane rainforest formations between 1285 and 2287 m: Gunung Kanino, Gunung Nokilalaki, Gunung Lehio, Rano Rano, Mamasa region (which includes Gunung Gandangdewata), Pegunungan Quarles, Gunung Rantemario, and Pegunungan Latimojong.

The other sample is from montane forest habitats between 1500 and 2000 m on Pegunungan Mekongga, the highest mountain complex on the southeastern peninsula of Sulawesi (highest point is 2500 m).

What other mountainous regions may harbor populations of B. penitus is unknown.

The range of B. penitus on the southeastern peninsula may be more expansive than is indicated by samples at hand. Northeast of Pegunungan Mekongga and south of Danau Towuti are ridges high enough (1500–2100 m) to support lower montane forests, but these highlands have not been surveyed for small mammals.

Pegunungan Pompangeo rises to more than 2500 m east of Danau Poso in the eastern sector of Sulawesi's core, and would also be a place to look for B. penitus.

Gunung Tambusisi, at the western end of the mountainous backbone along the eastern peninsula, has yielded Bunomys prolatus and Maxomys wattsi from its montane forests, but no B. penitus (see the account of B. prolatus). Whether B. penitus is absent from mountain forests covering higher elevations on Gunung Tambusisi and highlands east of there on the eastern peninsula or is replaced by B. prolatus or additional undescribed montane species of Bunomys can be determined only by careful trapping surveys.

Sympatry with Other Bunomys

In the west-central mountain block and on Pegunungan Mekongga, B. penitus is sympatric with B. chrysocomus; both species have been collected in the same trapline (see account of B. chrysocomus). With that exception, no other species of Bunomys has been found occupying the same montane habitat as B. penitus (table 5).

In addition to B. chrysocomus, other species of Bunomys occur in the west-central mountain block and on the southeastern peninsula, but their ranges are elevationally parapatric to that of B. penitus. In the northern part of the west-central mountain block, B. andrewsi and B. karokophilus, n. sp., inhabit tropical lowland evergreen rain forest, but are absent from montane forest formations. In the southern portion of the block on Gunung Gandangdewata in Pegunungan Quarles, B. penitus is sympatric with three other Bunomys but not elevationally syntopic: B. andrewsi has been collected in tropical lowland evergreen rain forest at 1600 m, B. penitus in montane forest at about 2000 m, and B. torajae higher at 2500 and 2600 m. On the southeastern peninsula, B. andrewsi is found in lowland habitats adjacent to Pegunungan Mekongga, but not in montane forests.

Description

One of the most handsome of the species of Bunomys, B. penitus was described in 1921 by Miller and Hollister from five specimens collected at about 6000 ft on Gunung Lehio in the mountainous central region of Sulawesi (locality 40 in the gazetteer and on the map in fig. 51). The Latin, penitus, means “internal,” “within,” “inward,” “inner,” or “interior” (Brown, 1956: 436, 597) and the authors (who provided no etymology) were likely referring to the provenence of the sample in that it came from the core or “interior” of the island.

Defining traits of “Rattus penitus” were provided by Miller and Hollister (1921a: 72) in their diagnosis that was based on five specimens:

Miller and Hollister (1921a: 73) remarked of “Rattus penitus” that “This large-snouted member of the chrysocomus group is very different from all the related forms ….”

After 1921, Miller and Hollister's generic and specific combination was listed in most treatises and checklists published in the 1930s and early 1940s (Tate, 1936; Ellerman, 1941). An exception was Sody (1941) who placed penitus in his newly described Frateromys, the genotype being F. fratrorum. Later, Ellerman (1949) and Laurie and Hill (1954) treated penitus as a subspecies of Rattus adspersus. By the 1980s, penitus had been transferred to Bunomys (Musser and Newcomb, 1983) and has been associated with that genus ever since (Corbet and Hill, 1992; Musser and Carleton, 2005; the present and past nomenclatural associations of penitus are summarized in table 4.

Bunomys penitus is, in body size, the largest member of the B. fratrorum group (LHB  =  155–242 mm, LT  =  138–190 mm, LHF  =  38–45 mm, LE  =  23–29 mm, W  =  95–170 g, ONL  =  39.3–46.1 mm), has a broad head, long rostrum, chunky body, beautiful, soft, and luxuriant fur, and a moderately long white-tipped tail (see the portrait of the species in fig. 6). The lustrous dorsal fur of adults is long (up to 25 mm) and very soft to the touch. Brownish gray speckled with buff is typical along the head, back, and rump (a result of the mixture of dark gray underfur, overhairs that are dark gray for most of their lengths and tipped brown and buffy bands, all intermixed with blackish guard hairs); sides of the body are paler—grayish brown. Because the guard hairs extend only slightly beyond the layer of overhairs, the surface of the fur feels smooth and looks even. The proximal portion of each forearm is encircled by dark gray. Sides of the muzzle are white.

The short (10–15 mm long) ventral coat is also soft and either grayish white or dark grayish white (tips of the gray hairs are unpigmented). On a few animals the underparts are grayish buff (the hairs are tipped with buff instead of being unpigmented) or a richer buffy gray. White patches (hairs are unpigmented for their entire lengths) occur on the chest, stomach, and inguinal region of many specimens in the sample. The contrast between dorsal and ventral coats is evident but not sharply demarcated. White tips of the hairs have altered to cream in older stuffed skins held for decades in museum collections, such as the specimens in USNM collected by H.C. Raven.

Ears (pinnae) are large and appear naked but are covered in short, fine, and unpigmented hairs. In life, the ears have a rubbery texture and are pigmented with gray and brown hues; gray, dark gray, grayish brown, and brownish gray marked the ears the freshly caught rats I examined. The dried ears of stuffed museum skins have lost the rubbery texture of the live animal and dry to dark brown with no hint of the actual range in hue and tone.

The tail ranges from slightly shorter to longer than the combined length of head and body (LT/LHB  =  88%–102%; see table 41), and is bicolored except for the white tip. The entire ventral surface is glossy white in all animals I studied (best appreciated in freshly caught rats) and the white envelops all surfaces of the tail tip in 83%–100% (mean  =  98%) of the specimens surveyed where the tip forms 3%–68% (mean  =  21.0%) of the total tail length (table 8). Behind the white tip, coloration of the dorsal surface and sides vary. The hues and tones I recorded from freshly caught rats are blackish gray (rare), dark glossy gray, grayish brown, and brownish gray (most common); two rats have a mottled gray dorsal covering between base of the tail and the white tip.

Front and hind feet are long and slender. Digits are white, and specimens in about 60% of the sample have white dorsal metacarpal and metatarsal surfaces; in the rest of the sample, these dorsal areas are white suffused with pale gray, dark gray, or pale brown. A few animals have white front feet and grayish or brownish hind feet. The naked palmar and plantar surfaces are either unpigmented or show gray tones. Claws are unpigmented, those on the front digits are very short relative to lengths of the digits and appear weak; a few ungual hairs spring from the base of each claw. Claws on the hind feet are longer and nearly completely concealed by long and dense tufts.

Females have four teats, arranged in two inguinal pairs. The scrotal sac of males is gray and sparsely haired (appears naked), and the testes are small relative to body size (9%–13%; table 9). Spermatozoan morphology is described by Breed and Musser (1991).

The juvenile coat covering upperparts of the head and body is duller and darker than that of the adult fur—a muted grayish brown (lacks buffy overhair tips). It is dense, fine, and very soft to the touch. Underparts are grayish white as in the adults, but the hairs are finer and shorter. White patches are prominent on the chest and inguinal region. Ears are dark gray or grayish brown. Front and hind feet are pigmented as in the adults. The tail pattern is also similar: glossy white over the ventral surface and around the tip, glossy dark gray or grayish brown on the dorsal surface and sides behind the tip.

The large skull of B. penitus with its long and wide rostrum and narrow zygomatic plate is distinctive (figs. 52–Fig. 53.54, 73; tables 42, 61, 62). Among members of the B. fratrorum group, only B. karokophilus, n. sp., possesses as narrow a zygomatic plate (see table 42). Other noteworthy traits of B. penitus are its relatively narrow interorbital region, long and broad incisive foramina, long palatal bridge, wide mesopterygoid region, and large ectotympanic bullae. Each dentary is similar in shape to those of other members in the B. fratrorum group, with the exception of its longer incisor sheath anterior to the molar row.

Large molars with simple occlusal patterns are typical of B. penitus (figs. 74, 75; table 10). On the first upper molar, a large labial cusplet sits adjacent to or is partially merged with cusp t6 in 30% of the sample (fig. 75), a configuration not present in other species of the B. fratrorum group or in members of the B. chrysocomus group. Cusp t3 is present on the second upper molar in 62% of the sample, but is rarely seen on the third molar (5%), although when present is often large (fig. 75). As in other species of Bunomys, an anterior labial cusplet is generally absent from the first lower molar, but a posterior labial cusplet typically forms part of the chewing surfaces of both the first and second lower molars (figs. 74, 75). An anterolabial cusp is present on the second lower molar in about half the sample (55%) but absent from the third molar in all specimens surveyed (fig. 74; table 11).

Fig. 74.

Occlusal views of right maxillary (left pair) and mandibular (right pair) molar rows from two specimens of Bunomys penitus. A, very young adult showing slight wear (AMNH 223856; CLM1–3  =  7.5 mm, clm1–3  =  7.5 mm). B, adult with average degree of wear (AMNH 225274; CLM1–3  =  7.6 mm; clm1–3  =  7.8 mm). Note the absence of a labial cusplet next to the large cusp t6 on the first upper molar (such a labial cusplet is shown in fig.75); of 215 specimens surveyed, 150 (70%) lacked the cusplet. An anterolabial cusp sits at the anterolabial corner of the second lower molar in about half the sample (55%) but is absent from the third molar (table 11).

Fig. 75.

Occlusal views of right maxillary (A, B) and mandibular (C) molar rows illustrating variation in particular cusps and cusplets in the sample of Bunomys penitus. On the first upper molar in 65 of 215 specimens surveyed (30%), there is a large labial cusplet (short arrows) that is either separate from the adjacent cusp t6 (as in A) or partially merged (but still evident) with the larger cusp t6 (shown in B); contrast this pattern with the usual configuration shown in figure 74 where a labial cusp is not present. Cusp t3 (long and thin arrows) occurs (B) on the second upper molar in 62% of the sample surveyed, but is absent from the remainder of the sample (as in fig.74A), and is part of the third molar (B) in only 5% of the sample (table 10). All specimens surveyed exhibit a small, moderately large, or huge posterior labial cusplet (stubby arrow in C) on the first lower molar (as exhibited by the lower molars in figs.74 and 75); an anterior labial cusplet is rare (table 11). The second lower molars of nearly all specimens in the sample also bear posterior labial cusplets (stubby arrow in C) with a comparable range in size. The second lower molar in C is without an anterolabial cusp, which is absent in about half the sample (45%) and absent from the third molar in all specimens surveyed (table 11). A, AMNH 223818 (CLM1–3  =  7.7 mm); B, AMNH 223846 (CLM1–3  =  7.8 mm); C, AMNH 223844 (clm1–3  =  7.2 mm).

Karyotype

2N  =  42, FNa  =  58 for both sexes, FNt  =  60 for females and 61 for males, comprised of seven pairs of metacentric chromosomes, two pairs of subtelocentrics, and 11 pairs of acrocentrics; the presumed sex chromosomes of the female are acrocentrics, the male has an acrocentric and a submetacentric (table 12).

Comparisons

Samples of B. penitus were compared with those of B. torajae, B. fratrorum, and B. andrewsi in the accounts of those three species; contrasts between B. penitus and B. karokophilus, n. sp., will be addressed in the account of the latter. Here B. penitus requires comparison with two members of the B. chrysocomus group, B. chrysocomus and B. prolatus.

Bunomys penitus and B. chrysocomus: Voucher specimens record the sympatry of B. chrysocomus and B. penitus on Gunung Kanino, Gunung Lehio, and Gunung Latimojong in the west-central mountain block, and Pegunungan Mekongga on the southeastern peninsula (see table 20 and the account of B. chrysocomus). The two species are not difficult to distinguish. Adult B. penitus average larger in body size, with longer appendages (tail, hind foot, and ear) and greater mass than the smaller-bodied B. chrysocomus (table 74). Bunomys penitus is grayish, the upperparts are soft and silky, dense (up to 25 mm long), and brownish gray; underparts are grayish white; the rhinarium is unpigmented and sides of the rostrum are white; tops of front and hind feet are either solid white or tinged with gray; and the tail is glossy brownish gray along the dorsal surface until the last 5–118 mm (3%–68% of the tail length, mean  =  21.0%), which is white as is the entire ventral tail surface—nearly every specimen surveyed exhibits a white tail segment (98% of 293 specimens; table 8). Bunomys chrysocomus is dark brown, the dorsal coat is soft and thick but not silky, and not as long (12–15 mm thick) as that in B. penitus, and is dark brownish gray speckled with buff; the rhinarium and sides of the rostrum are dark brown; the ventral coat is grayish white and washed with rust or buff in a few specimens; metacarpal and metatarsal surfaces are grayish white to brown; the tail is brown over its upper surface, whitish speckled or mottled with brown along the ventral surface (rarely white), and most specimens lack a white tip—when present it is short (1%–25% of the tail length, mean  =  6%) and found in only 20% of the sample containing 396 specimens (table 8). Bunomys penitus has short, delicate claws on the front digits; B. chrysocomus has much longer claws, both absolutely and relative to body size.

Relative to body size, the testes are small in B. penitus (9%–13%) but large in B. chrysocomus (22%; table 9), and this contrast is obvious in freshly trapped adult males. Shape of the spermatozoa is similar in the two species, but that of B. penitus has a wider head, shorter apical hook, and shorter spermatozoan tail (Breed and Musser, 1991).

Both species have a 2N of 42, but different fundamental numbers (FNa  =  58 and FNt  =  60–61 for B. penitus and FNa  =  56 and FNt  =  58 for B. chrysocomus; table 12).

Bunomys penitus has a large skull and massive molars compared to B. chrysocomus, but the latter has a broader zygomatic plate and bony palate. The magnitude of differences in cranial and dental dimensions tabulated in tables 59 and 74 in the form of descriptive univariate statistics can be visually examined in the cranial images (figs. 99–Fig. 100.101), and viewed in the scatter plot of specimen scores projected onto first and second principal components (fig. 76, upper graph). In that ordination, separation of scores along the first axis for the larger B. penitus (the aggregation on the right side) and smaller B. chrysocomus (the cloud on the left) is facilitated by the large and positive correlations (r  =  0.65–0.96) for all variables except breadths of zygomatic plate and bony palate, which are negative, reflecting the greater magnitude of most variables for B. penitus but its narrower zygomatic plate and bony palate as compared with B. chrysocomus (table 60).

Fig. 76.

Specimen scores representing all population samples of Bunomys penitus (inverted filled triangles; N  =  185), B. chrysocomus (filled upright triangles; N  =  232), and B. prolatus from Gunung Tambusisi (asterisks; N  =  8) projected onto first and second principal components extracted from principal-components analysis of 16 cranial and two dental log-transformed variables. Upper graph: B. penitus contrasted with B. chrysocomus. Lower graph: B. penitus compared with B. prolatus. See table 60 for correlations (loadings) of variables with extracted components and for percent variance explained for both ordinations.

The two species exhibit minor topographic differences on occlusal molar surfaces. There is no large labial cusplet adjacent to cusp t6 in all the specimens of B. chrysocomus I examined (present in 30% of the sample of B. penitus). Cusp t3 on the second upper molar occurs far more frequently (62%) in the sample of B. penitus, but is relatively uncommon (17%) in the large sample of B. chrysocomus (table 10). Just the reverse is the case for the anterior labial cusplet on the first lower molar, which is found in about half (52%) of the B. chrysocomus sample, but is rarely seen (8%) in the sample of B. penitus (table 11). On the second lower molar, an anterolabial cusp is nearly standard for B. chrysocomus (90%) and is also found on the third lower molar of that species in 65% of the sample; the comparable cusp occurs in only about half of the sample of B. penitus and is absent from the third lower molar of all specimens surveyed for this trait.

Bunomys penitus and B. prolatus: The species of Bunomys living in montane habitats on Gunung Tambusisi, at the western margin of the eastern peninsula, is B. prolatus, not B. penitus, and the former may replace the latter in montane forest formations in the mountain backbone of the eastern arm. Alternatively, B. prolatus may occur on some highlands and B. penitus on others, or both may inhabit the same montane forests—survey of those eastern peninsular highlands for small mammals has been scanty. Both species are characterized by large body size and lush gray pelage; those traits along with what may be an interesting displacement pattern of their geographic distributions warrants comparing them.

Certain external aspects of B. penitus and B. prolatus are similar. Both have brownish-gray or grayish-brown upperparts, the fur is thick, long, and soft, the underparts of both are grayish white, and each has a long muzzle and large ears. Bunomys penitus, however, is a physically larger animal as evidenced by its average longer head and body and longer hind foot (compare measurements for B. prolatus in table 19 with those for B. penitus in table 41). Bunomys penitus has a much longer tail, not only absolutely (means  =  162.5–169.1 mm for two samples of B. penitus; mean  =  132.4 mm for B. prolatus), but also relative to length of head and body (range of means  =  88%–93% in B. penitus, 79% in B. prolatus). While the tail in nearly every specimen of B. penitus has a long white terminal segment, is brownish gray or paler on the dorsal surface behind that unigmented tip, and pure white along the ventral surface, only one of seven examples of B. prolatus has a short white tip (table 8), and the undersurface ranges from all white through white speckled with brown to brown nearly indistinguishable from the dorsal surface. Finally, the small and delicate front claws in B. penitus are unlike the robust and elongate front claws typical of B. prolatus (fig. 36).

All but two of the cranial and dental dimensions I measured average greater in the sample of B. penitus compared with that of B. prolatus (table 59). Bunomys prolatus has a wider interorbital region, and the ectotympanic bullar capsule is about the same length in both species, reflecting the close resemblance between the two in size of pinnae (see the values for B. prolatus listed in table 19 and for B. penitus in table 41).

Specimen scores projected on first and second principal components coalesce into two discrete aggregations along the first component (fig. 76, lower graph), providing a multivariate summary of size differences between the two species in cranial and dental measurements, as indexed by the moderate to large and positive correlations among nearly all variables (r  =  0.25–0.84; table 60). Compared with B. prolatus, B. penitus has a larger skull, more prominent rostrum, more spacious mesopterygoid fossa and incisive foramina, and larger molars, all attributes that can be seen when the cranial images of B. prolatus in figures 37–Fig. 38.39 are compared with the cranial portrayals of B. penitus in figures 52–Fig. 53.54.

Proportional interplay among the variables is indicated by the postion of scores along the second axis. The upper cloud of scores for B. prolatus separated from the lower and larger constellation for B. penitus reflects the relatively wider interorbit of B. prolatus compared with B. penitus; its relatively longer rostrum, diastema, and postpalatal region; wider zygomatic plate and more spacious bony palate, but weaker molars, as indicated by the moderate to high positive or negative loadings for these variables (table 60).

Frequencies of certain molar cusps differ in the two species. Every one of the four examples of B. prolatus lacks cusp t3 on the second upper molar (eight comprise the sample, but occlusal surfaces of four are too worn to determine presence or absence of certain cusps and cusplets), but the comparable structure characterizes 62% of the large sample of B. penitus (table 10). None of the examples of B. prolatus show a labial cusplet adjacent to cusp t6 (present in 30% of the sample for B. penitus; fig. 75). An anterolabial cusp is present on the second lower molar in each of the four B. prolatus, and is also seen on the third lower molar in three of the four specimens; only 55% of the sample of B. penitus exhibits the cusp on the second molar, no specimen shows the cusp on the third molar (table 11).

Geographic Variation

Population samples of B. penitus come from two highland regions: the west-central mountain block in Sulawesi's core (Gunung Kanino, Gunung Nokilalaki, Gunung Lehio, Rano Rano, Mamasa Area, Pegunungan Quarles, and Pegunungan Latimojong) and Pegunungan Mekongga, the mountain complex on the southeastern peninsula of Sulawesi. In the west-central mountain block, gene exchange is likely prevalent among populations where montane habitats are continuous in particular stretches of high ridges and peaks, but interrupted among montane patches separated by tropical lowland evergreen rain forests in intermontane valleys and river gorges. Some degree of phenetic variation among samples should be expected in this extensive mountainous landscape.

In relation to samples from the west-central mountain block, that from the Mekongga range is isolated on the southeastern peninsula of the island. Certainly some phenetic differences should be expected between populations in the core and those on the southeastern peninsula. One of my aims in assessing geographic variation among population samples of B. penitus was to determine whether those samples from Pegunungan Mekongga represented a separate species.

There is geographic variation in some of the characters I examined, but the magnitude of difference is not great. No appreciable qualitative variation among available populations of B. penitus is evident in external traits, at least that I could detect. Whatever the montane provenance of a sample, individuals of comparable age are similar in physical size and look closely similar in other external traits from sample to sample: a thick, soft, and silky brownish-gray dorsal coat; dense grayish-white underparts; relatively large, rubbery grayish-brown ears; white feet, lightly suffused with gray in some individuals; a slender tail that is coequal with length of head and body, the proximal three-fourths of its dorsal surface grayish brown or paler, the distal segment and entire ventral surface pure white.

I examined skulls in all the population samples and did not detect any qualitative traits that were associated with particular geographic regions or any pattern indicated by descriptive statistics for cranial and dental measurements (tables 61, 62). A similar picture was generated by results from quantitative analyses of cranial and dental variables using one multivariate technique, but two other multivariate approaches produced a more revelatory pattern.

A scatter plot of specimen scores projected on first and second principal components produced no apparent pattern reflecting covariation among the variables correlated with geography (fig. 77, upper graph). Scores for specimens in the large samples from Gunung Kanino and Gunung Nokilalaki in the west-central mountain block are spread along both axes and overlap nearly every score for specimens from other collection sites in that mountain block (Rano Rano, Gunung Lehio, Mamasa Area, and Pegunungan Latimojong) as well as scores for the sample from Pegunungan Mekongga on the southeastern peninsula. Ordinations (not illustrated here) bounded by the combinations of first and third, and second and third components showed similar patterns of specimen scores. Covariation in most variables is responsible for the dispersal of scores along the first axis (r  =  0.31–0.76), with breadths of zygomatic plate and mesopterygoid fossa most influential (table 63). Rather than identifying significant intraspecific geographic variation or separate clusters possibly indicating the presence of more than one species, the spread of scores, signifying both size (first component) and shape (second axis) factors, more likely reflects individual variation as well as the range of variation in variables due to age within my young to old adult categories.

Fig. 77.

Specimen scores representing all population samples of Bunomys penitus projected onto first and second principal components extracted from principal-components analysis (upper graph) and on first and second canonical variates extracted from discriminant-function analysis (lower graph) of 16 cranial and two dental log-transformed variables. Symbols: filled circles  =  Gunung Kanino (N  =  74); empty circles  =  Gunung Nokilalaki (N  =  82); empty triangles  =  Rano Rano (N  =  3); empty squares  =  Gunung Lehio (N  =  5); empty right-pointing triangles  =  Mamasa area (N  =  7); asterisks  =  Pegunungan Latimojong (N  =  3); filled squares  =  Pegunungan Mekongga (N  =  11). Arrows point to scores for holotypes: penitus (empty square) and sericatus (empty triangle). See table 63 for correlations (loadings) of variables with extracted components and canonical variates and for percent variance explained that apply to both ordinations.

A fuzzy pattern of geographic variation emerged from results of discriminant-function analysis where individual specimen scores from the population samples are projected on first and second canonical variates (fig. 77, lower graph). The large cluster of scores for Gunung Kanino and Gunung Nokilalaki also contains nearly all points for specimens collected elsewhere in the west-central mountain block. Two outliers are the five specimens from Gunung Lehio, with a slightly longer postpalatal region and narrower zygomatic plate compared with the other samples from the mountain block, and the three specimens from Pegunungan Latimojong that show an average wider skull (indicated by zygomatic breadth) and zygomatic plate along with longer incisive foramina (see tables 61 and 62). The significance of these average differences is unclear because the samples from Gunung Lehio and Pegunungan Latimojong are so small relative to the very large series from Gunung Kanino and Gunung Nokilalaki.

Scores representing the sample from Pegunungan Mekongga on the southeastern peninsula (N  =  11) lie to the left relative to position of the scores for the other samples in the ordination, all of them from the west-central mountain block (fig. 77). An overall smaller skull, both shorter (measured by occipitonasal length) and narrower (indexed by zygomatic breadth and breadths of interorbit and braincase) shorter basicranium (postpalatal length), smaller bullae, and shorter molar row characterizes the sample from Pegunungan Mekongga compared with those collected in the west-central region (see the univariate descriptive statistics in table 62); breadth of braincase and lengths of bulla and molar row are especially forceful in spacing the scores along the first canonical variate, with those for Pegunungan Mekongga at one end of the spread and the points representing Gunung Kanino and Gunung Nokilalaki at the opposite (fig. 77, table 63).

Lengths of head and body, tail, and hind foot also average shorter in the sample from Pegunungan Mekongga compared with those series collected in the west-central mountain block (table 41). The contrast in these cranial and external variables suggests underlying partial genetic isolation between populations living in the two mountainous landscapes.

Cluster analysis resulted in a pattern of montane variation that for most samples mirrored the relative position of their highland collection sites (fig. 78). The clustering pattern based on squared Mahalanobis distances unites first the samples from Gunung Nokilalaki and Gunung Kanino (which is a high ridge leading to Nokilalaki) within a cluster comprised also of Rano Rano (highlands just east of Kanino and Nokilalaki), Gunung Lehio (west of the latter three locations and across the valley of the Sungai Miu), and the Mamasa Area (to the south of those four places)—all part of the west-central mountain block. Those five are linked to Pegunungan Mekongga on the southeastern peninsula. Pegunungan Latimojong, in the southern part of the west-central mountain block, connects to the sample from Pegunungan Mekongga rather than to samples from the west-central mountain block. I do not know whether this last link reflects a real phenetic relationship or is an artifact of sample size.

Fig. 78.

Upper diagram: Pattern of phenetic relationships among population samples representing Bunomys penitus derived from UPGMA clustering of squared Mahalanobis distances among group centroids as based on discriminant-function analysis. Lower diagram: Specimen scores representing two samples of B. penitus projected onto first and second principal components extracted from principal-components analysis of 16 cranial and two dental log-transformed variables. Combined population samples from the west-central mountain block (Gunung Lehio, Gunung Kanino, Gunung Nokilalaki, Rano Rano, Mamasa Area, and Pegunungan Latimojong) form one sample (filled circle); the lot from Pegunungan Mekongga on the southeastern peninsula constitutes the other (empty circle). Ellipses outline 95% confidence limits for each group centroid. Equations for the regression lines are: West-central mountain block, Y  =  −0.004 × 0.000 (F  =  0.005, P  =  0.941); Pegunungan Mekongga, Y  =  −0.023 × −0.001 (F  =  0.051, P  =  0.826). Neither the slopes of the two regression lines or their Y-intercepts are statistically significant (see discussion in text). The ordination in figure 77 shows the same distribution of scores but with individual samples identified; correlations of variables and percent variance in table 63 apply to both principal-components diagrams.

Compared with samples from the west-central mountain block, that from Pegunungan Mekongga differs by its average shorter and narrower skull, shorter basicranium, smaller bullae, and shorter molar row as reflected in the tables of summary statistics (table 62) and results of discriminant-function analysis (fig. 77; table 63) described above. These distinctions, plus the isolated geographic position of the Mekongga population relative to those occurring in the west-central mountain block, prompted me to run an additional principal-components analysis that employed only two samples: one containing the combined six population samples from the west-central mountain block, the other consisting of the smaller sample collected on Pegunungan Mekongga. Results might reveal a sharper pattern of cranial and dental differentiation between samples from the two mountainous regions and better test whether the samples from the west-central mountain block and that from the mountain range on the southeastern peninsula represent two species rather than one.

In an ordination bounded by first and second principal components, the usual pattern of scores representing two morphologically closely related but different species consists of two slightly overlapping and obliquely oriented elliptical clouds in which the major axes (regression lines) of the spreads are phenetically discrete—the regression lines of the second principal component on the first are clearly separate and their Y-intercepts are significantly different between the two species (see Voss et al., 1990; Voss and Marcus, 1992). This is the pattern illustrated in the principal components ordination comparing samples of B. chrysocomus with the morphologically similar B. coelestis (fig. 42); other examples are provided by Carleton and Martinez (1991), Carleton and Musser (1995), Carleton et al. (1999, 2006, 2009), Carleton and Byrne (2006), Carleton and Arroyo-Cabrales (2009), Carleton and Stanley (2012), Musser et al. (1998), and Voss et al. (2002) for Mexican, Central American, South American, and African muroids; by Anderson and Gutiérrez (2009) for South American heteromyid rodents; and by Musser et al. (2010) for Sulawesi squirrels. No such dual ellipsoidal patterns characterize the distribution of scores for the two samples of B. penitus (fig. 78, lower graph). The two regression lines are essentially horizontal (their slopes statistically the same; −0.004 versus 0.023, F  =  0.039, P  =  0.844), overlap for much of their lengths, and their Y-intercepts are not significantly different (0.000 versus 0.001, F  =  0.210, P  =  0.885). Statistically, there is a single major linear axis of one large assemblage of scores, reinforcing the interpretation of a single species showing geographic variation in some cranial and dental variables.

This pattern of variation contrasts with that characterizing other murid groups occurring in the Mekongga region having counterparts in the west-central mountains. Taeromys arcuatus, Taeromys microbullatus, Maxomys n. sp., Margaretamys christinae, and Rattus salocco, for example, are known only from Pegunungan Mekongga (see table 81), and their counterparts in the west-central mountain block are two new species of Taeromys, Taeromys callitrichus, Maxomys dollmani, Margaretamys parvus and M. elegans, and Rattus facetus, respectively (documented in manuscripts in prep.).

Present samples of B. penitus provide one pattern of variation in cranial and dental variables among highland populations; that picture may be altered or substantiated after study of material from unsampled highlands and larger series from some of those places recorded here. Aside from the samples from Gunung Kanino and Gunung Nokilalaki, the other population samples are small, three to seven useable intact specimens in those from Rano Rano, Gunung Lehio, Mamasa Area, and Pegunungan Latimojong, and 11 in the Pegunungan Mekongga lot (tables 61, 62). Larger series from these latter five places would allow sorting of specimens into age groups and comparing sets of similar relative age, which would provide sharper resolution of any intersample variation. The pattern revealed here does provide a hypothesis that can be tested with measurements of external and cranial variables from more and larger samples, and eventually with results from analysis of DNA sequences.

Natural History

Summarized here are my observations covering habitat and diet derived from the animals collected along my transect that culminated on Gunung Kanino and Gunung Nokilalaki in the cool and wet primary tropical lower and upper montane rain forests.

Habitat: Mean ambient air temperatures ranged from 58.4° to 64.8° F on Gunung Kanino (1440 m), and 57.5° to 64.8° F at 1730 m on Gunung Nokilalaki and 51.0° to 56.6° F on the summit (see table 3 relative humidity and rainfall patterns are also listed). A portion of the trapping sites are described in table 64 (the descriptions are selected to cover the range of microhabitats trapped and not to document where every rat was taken).

During about two months at different times camped on Gunung Kanino (October 27–November 23, 1973, and January 17–February 16, 1975) and longer on Gunung Nokilalaki (December 7–30, 1973; February 22–May 15, 1975), we collected 288 Bunomys penitus. This was the most frequently trapped murid in these montane habitats, followed by Paruromys dominator (201 examples), Rattus hoffmanni (92 specimens), Maxomys musschenbroekii (73 individuals), and Margaretamys elegans (40 specimens); see figure 103. And except for the lower edge of lower montane forest between 1274 and 1555 m where we trapped both B. penitus and B. chrysocomus, the former is the only representative of Bunomys in montane habitats on Gunung Kanino and Gunung Nokilalaki, ranging from the lower boundary of lowland montane forest at 1274–1300 m all the way to the summit of Gunung Nokilalaki at 2287 m.

Bunomys penitus is nocturnal and terrestrial; we never trapped any examples on substrates above ground level.

Gunung Kanino forms a highland mass attached to the southwestern shoulder of the higher ridge forming Gunung Nokilalaki. Its northwestern margin is defined by the Sungai Tokararu, which drains into Danau Lindu (see area at right in the distribution map in fig. 51). The base of Kanino is mantled by lowland tropical evergreen rain forest where our camp at 1150 m was located on a terrace above the Sungai Tokararu. Upslope at (1296–1311 m), the lowland forest transitions sharply into lower montane formations defined by the beginnings of chestnuts (Castanopsis acuminatissima) and Calophyllum that form extensive groves covering the slopes and terraces up to about 1800 m (fig. 79). Here the chestnuts are dominant and form most of the canopy with mature trees attaining 80–100 ft high, some reaching about 125 ft. They are spaced 15 to 20 ft apart. The ground is mossy but also thickly covered with leathery-brown chestnut leaves forming a dry litter that crackles under foot. Here Calophyllum is also abundant, both as young trees throughout the understory and as scattered canopy trees; they outnumber the scattered oaks (Lithocarpus glutinosus and L. elegans) and the forest could be described as a chestnut-calophyllum climax. This ratio changes with altitude and oaks become as abundant as Calophyllum (chestnut-oak-Calophyllum climax) and then exceed it in numbers as the latter and chestnuts become scattered and rare, with the oaks, primarily Lithocarpus havilandii, growing on higher slopes above the chestnut, where they form extensive groves in places, all the way to the summit of Gunung Nokilalaki. Stands of the conifer dammar (Agathis philippinensis) along with a variety of other canopy as well as understory trees contribute to the lower montane forest composition (see legend to fig. 79). Bunomys penitus was frequently encountered in these chestnut-oak-Calophyllum groves between 1300 and 1600 m, 49% of all specimens trapped in lower and upper montane forest (see fig. 103 and the trapping sites described in table 64).

Fig. 79.

Coppice of old-growth chestnut (Castanopsis acuminatissima) in primary lower montane forest at 1463 m on Gunung Kanino (in 1975). Shoots growing from the base of a single tree into a cluster of trunks dominated by one or two large trunks, each reaching 2 ft in diameter, is the typical growth morphology. The base, encrusted with moss and epiphytes, may be 5–8 ft wide and as high, and hollow or honeycombed with passages. Bunomys penitus was trapped in and around the hollow moss-covered base. These clusters of chestnut trunks, as well as single trees with trunks 3–4 ft in diameter, contribute to the canopy (reaching 80–125 ft) along with Calophyllum sp. About 100 ft higher on the ridge, oak (Lithocarpus glutinosus and L. elegans) replaces Calophyllum and the ridges are dominated by an oak-chestnut forest. This lower montane region is shared by species of Eugenia and Syzygium; Symplocos; the laurels Cryptocarya, Litsea, Endiandra, and Cinnamomum; the nutmeg Knema; magnolias (Magnolia spp.); the maple Acer caesium; walnut (Engelhardtia serrata); the conifers Agathis philippinensis, Dacrycarpus imbricatus, Podocarpus neriifolius P. rumphii; the canopy figs Ficus sumatrana and F. crassiramea; Madhuca malaccensis in Sapotaceae; Macadamia hildebrandii in Proteaceae; and a variety of understory tree species; rattan is common and the palm Areca vestiaria is scattered.

Although most B. penitus were caught in either chestnut-oak-Calophyllum forest or higher in upper montane habitats near the summit of Gunung Nokilaki, we also found them at intervening elevations, even in ridgetops covered by short forest dominated by Tristania and Pandanus (fig. 80). Generally, every line of traps set at different elevations in montane forest yielded examples of B. penitus.

Fig. 80.

Ridge-top forest between 1600 and 1700 m on Gunung Kanino (in 1975) dominated by Tristania sp. (with the whitish bark) and species of Eugenia, especially E. cuprea; pandans (Pandanus sp.) are common, as are two species of Vaccinium—one a canopy former, the other in the understory—and rattan is abundant; the fern Dipteris blankets open spaces. Canopy is 50–60 ft high with the occasional chestnut or oak, which have small trunks here, emerging to about 70 ft. Tristania bark appears white from a distance but up close is actually streaked with gray, tan, rusty pink, and pale orange. Around the bottoms of some trunks are piles of pandan debris and sloughed Tristania bark, forming mounds 1–3 ft high and 3–5 ft wide that provide excellent cover for Bunomys penitus.

About 39% of the 288 B. penitus were trapped between 2000 m and the summit of Gunung Nokilalaki in densely mossy, cool, and wet upper montane forest (see figs. 81–Fig. 82.83, 103; also see the descriptions of this forest provided in Musser, 1982). Near and on the summit, all the rats were trapped in runways—usually damp and either muddy or carpeted with moss—beneath isolated decaying trunks, under tangles of trunks, limbs, and branches formed from old treefalls, inside rotting stumps, and within spaces among moss-covered roots of living trees (table 64).

Fig. 81.

Primary upper montane rain forest at 2256 m (in 1975) near the summit of Gunung Nokilalaki. The forest is open, lacking the closed canopy so typical of forest formations at lower elevations. Oak (Lithocarpus havilandii) is common and joins magnolia (Magnolia sp.), bayberry (Myrica javanica), and conifers (species of Dacrydium and Podocarpus) as the largest trees; species of Eugenia, Praravinia, Vaccinium, Symplocos, Astronia, Ternstroemia, Elaeocarpus, Litsea, Cryptocarya, Melastoma, and the occasional Ficus are among the many species of smaller trees. The climbing pandan (Freycinetia) winds through the tree crowns; here and there slender rattan stems (Calamus and Daemonorops) drape below the crowns. Sedges form much of the ground cover in this spot. Bunomys penitus is common in this cool and wet mossy habitat where we trapped them on wet ground within the sedge cover, and along sides of the moss-covered roots, decaying trunks lying on the ground, and rocks.

Fig. 82.

A different aspect of upper montane forest at 2256 m below the summit of Gunung Nokilalaki (in 1975). These forest glades, surrounded by tall trees enveloped with dense and wet moss, support a community of small gingers, rattan rosettes, several kinds of ferns, saplings, and a variety of small shrubs. We trapped Bunomys penitus beneath this floral cover as well as in the surrounding forest. Twelve other species of murids were collected here in the nearby forest, with Paruromys dominator, Rattus hoffmanni, Melasmothrix naso, Maxomys musschenbroekii, and Margaretamys parvus being the most common next to B. penitus at this elevation (see fig.103).

Fig. 83.

Forest margin of Gunung Nokilalaki's summit, 2287 m (in 1975). Part of the forest was opened by a fallen tree that is now decaying on the ground and completely cushioned in dense, wet moss. The jumble of trunks and branches provides superb cover for rodents, especially B. penitus, individuals of which were trapped beneath the pile as well as along the base of the large tree to the left, and beneath the mossy trunk in the foreground.

The montane habitats in which B. penitus were collected lack the floristic species diversity found in tropical lowland evergreen rain forest (see Natural History in account of B. chrysocomus). We collected samples from about 150 species of trees, and while some of these also occur in lowland forest most are found only in montane habitats. Except for six species of rattans (Calamus and Daemonorops), only the solitary palm Areca vestiaria was seen scattered in the forest at high elevations. There are fewer kinds of shrubs, pandans, gingers, and ground ferns; tree ferns are scattered through the forest from the beginning of lower montane forest to the summit of Gunung Nokilalaki.

Diet: Bunomys penitus consumes invertebrates, small vertebrates, some fruit, and a variety of fungi (table 13) and can be viewed primarily as an invertebrate and fungal predator. I kept up to 15 adults captive for several weeks in the camps on Gunung Kanino and Gunung Nokilalaki and offered them a range of foods. Invertebrates and fungi were the items most voraciously consumed. All were picky about fruits, accepting only seeds of oaks (Lithocarpus). Back at the museum I extracted the contents from 97 stomachs, which fell into the following categories: (1) six were empty except for matted hair ingested during grooming; (2) one contained unidentifiable remains; (3) 16 contained only bait (ranging from stomachs distended with bait to stomachs nearly empty except for remnants of bait, usually raisin and bacon fragments); (4) four were filled with arthropods and snails but no fungi; (5) six held remains of fruit and no fungi; (6) 64 held fungal remains only or fungi mixed with bait, arthropods, snails, or fruit in different combinations.

Below I present the foods eaten by B. penitus drawn from my observations of captive animals and study of the contents extracted from stomachs.

Earthworms—All the captive rats consumed earthworms (2–3 inches long) and handled them in a manner similar to that described for Bunomys chrysocomus (see that account). Each rat would aggressively grab the worm with incisors, and quickly transfer it to the front feet. The rat placed one end of the worm in its mouth, cutting it into segments while it pulled the worm through its front feet until entirely consumed, a process taking 20–30 seconds.

Only one of the 97 stomachs contained short unchewed segments of a small earthworm and this low frequency may be related to where the earthworms occur in montane forest and the ability of B. penitus to obtain them. We occasionally saw an earthworm crawling over open muddy ground after a hard rain, but we found most of them living beneath thick layers of moss covering decaying trunks, limbs, and smaller branches. Some we located beneath the bark of fallen trees not yet densely mantled with moss; rotting pieces of oaks (Lithocarpus) provided the most abundant earthworm accumulations. Except for the occasional earthworm squirming on muddy ground, which B. penitus could snatch up quickly, most would have to be excavated from beneath thick moss, which would be more difficult for the rat because its front claws are short and appear weak, at least as compared with the elongate front claws of B. chrysocomus and the montane species of Melasmothrix and Tateomys, all aggressive earthworm predators.

Snails—Managing snails was similar to the behavior described for B. chrysocomus (see that account). A snail was grabbed with the incisors, transferred to the front feet, turned over several times and eventually bitten into until enough shell was removed, so the soft body was exposed and could be extracted. Once accessible, the rat pulled away a bit of the flesh, ingested it, bit away more shell, pulled and ingested more of the tissue, and proceeded in this manner until the entire snail was consumed. The pieces of shell bitten off were always discarded. I never found fragments of the shell in stomachs, usually only an operculum along with partly digested tissue remains of the snail. Indications of snails were found in two of the 97 stomachs (semidigested tissue and operculum in one, maserated tissue, operculum, and fragment of radula in the other).

In the montane forest habitats on Gunung Kanino and Gunung Nokilalaki, snails seemed less common than in lowland rainforest environments and to average much smaller in size. I did locate snails within wet moss, sometimes crawling over wet leaf litter, here and there beneath decaying bark, and crawling up stems and onto leaves of sedges and other low ground cover.

Insects and other arthropods—Moths, cicadids, cockroaches, and beetles were provided and all consumed by the captive rats. Moths and cicadids were aggressively pulled from my fingers and quickly manipulated so the head was at the rat's mouth. It then bit the insect's head and proceeded to voraciously consume head, thorax, and abdomen—wings and legs were discarded.

Large adult beetles were always accepted, even those up to two inches long. The rats were selective, eating only the abdomen and soft parts of the thorax, and discarding everything else. Small beetles were totally ingested and were represented in the stomachs surveyed by elytra, wings, antennae, legs, along with abdominal and thoracic filamentous tissue. Beetle larvae were also consumed. A favorite were the large larvae (up to 4 inches long and ½ inch wide) I extracted from rotting wood; all the rats voraciously devoured these grubs.

Nine of the 97 stomachs held remains of insects and other arthropods: macrolepidopteran caterpillars, adult and larval beetles, cockroaches, and geophilomorph centipedes.

Remains of rhinotermitid termites, which I regularly found in stomachs of Bunomys chrysocomus and B. andrewsi that were trapped in tropical lowland evergreen rain forest, were absent from the stomachs of B. penitus. And I did not find any in stomachs of B. chrysocomus collected in lower montane forest on Gunung Kanino. The termites are either rare or may simply not occur in montane forest habitats. My helpers and I took apart many pieces of tree trunks and limbs in various stages of decay lying on the forest floor. We encountered earthworms along with adult and larval beetles but never termites (see the account of B. andrewsi where I provide an inventory of invertebrates, which includes termites, found in similar situations in lowland rainforest habitats).

Fruit—The meaty seeds of Lithocarpus were the only fruit consistently accepted by captive rats but only after I had extracted the seed from the hard shell. Of the 97 stomachs I emptied, nine contained remains of fruit, mostly fig (Ficus), a fruit with large oblong and dark brown seeds, and one with large flat hard and orange seeds.

Stomachs rarely contained only fruit. The content of a stomach from a rat trapped on Gunung Nokilalaki is illustrative. It was full with remains of a fig; another fruit with large, hard, and dark brown oblong seeds; fruit pulp, some bait; one small centipede, and several macrolepidopteran larvae.

Fungi—Different species of fungi form a significant part of the diet of Bunomys penitus, which is indicated not only by results from feeding trials but also by the prevalence of fungi in the stomachs I examined. I offered a variety of fungi to the captive animals. The two kinds of jelly or ear fungi so readily consumed by Bunomys karokophilus, n. sp. (see that account), the purplish Auricularia delicata (identified as karoko by the local people) and white Auricularia fuscosuccinea (Class Agaricomycetes, Order Auriculariales, Family Auriculariaceae) were consistently accepted and eaten. A shelflike gilled fungus Panellus pusillus (Order Agaricales, Family Trichyolomataceae), which I found attached only to decaying leaf shafts and stems of rattan decaying on the forest floor, was readily accepted and consumed. Seven kinds of stalked gill fungi with caps were offered to the rats and all were eaten. These mushrooms ranged in size from delicate fruiting bodies with a stalk 2 inches long and cap ½ inch wide to larger species with caps 3 inches in diameter and stalks reaching 3 inches. Cap and stalk of the smaller mushrooms were consumed, most of the cap of the larger mushrooms were eaten (sometimes a rat would eat only the soft underside of the cap) but the tough stems were left. I also found several kinds of shelflike jelly fungi other than Auricularia growing on rotting and wet wood and all these were consumed by the rats.

Not all the kinds of fungi offered the rats were accepted. Woody bracken fungi were ignored, as were puffballs, and a large stalked gilled mushroom with a thick brown and yellowish cap.

Of the 97 stomachs I cut open, 64 (66%) contained either only fungi or fungi mixed with remains of invertebrates and fruit in different combinations. Of these 64, 45 (70%) contained remains of a shelf fungus resembling Auricularia delicata but darker in color and rubbery rather than gelatinous in texture; of those 45, 16 held only the karoko-like fungus and some of these stomachs were distended with it.

The fruiting bodies of A. delicata form small and somewhat rubbery capsules (10 mm long, 5 mm wide) or broad and thick ear-shaped lobes (up to 50 mm wide) that grow on wet and decaying wood. The top surface is smooth and purplish or purplish brown, the undersurface white and irregularly ribbed and veined. The inside is gelatinous. Individual lobes may spread across the same wet and decaying tree trunk or limb, but usually several lobes form a cluster originating from a single point of attachment (see the account of B. karokophilus, n. sp., for a broader description of the fungus). The karoko-like fungus so prevalent in the stomachs of Bunomys penitus is dark brown, and tougher in consistency than A. delicata. In most stomachs, it appears as chewed rubbery lobes attached to a thick and tough (like hard rubber) translucent core. Fragments of the woody holdfast adhering to the core were in some stomachs, and slivers of wood and bits of moss occurred along with the fungus in other stomachs. Unfortunately, I have yet to identify this karoko-like fungus.

The combination of the karoko-like fungus with other items is illustrated by a stomach from a rat collected on Gunung Kanino: few segments of a small earthworm, remains of a snail (including the operculum and fragment of radula), fragment of cockroach leg, large rubbery chunks of the karoko-like fungus, and a few pea-sized globular fungi.

The other 19 of the 64 fungus-containing stomachs held remains of the two species of Auricularia, the Panellus, and several kinds of pink and yellow jelly fungi that I have not identified.

Overview—Bunomys penitus is mycophagous, incorporating a variety of ear, jelly, and gilled fungi in its diet, and is also an aggressive and agile predator of insects, centipedes, earthworms, and snails.

Ectoparasites, Pseudoscorpions, and Endoparasites

Fleas and ticks comprise the ectoparasites recorded from Bunomys penitus (table 14). Of the species in the six genera of fleas (Siphonaptera) that parasitize B. penitus, Sigmactenus sulawesiensis (Leptopsyllidae) also parasitizes four other endemic Sulawesi murines (Bunomys fratrorum, Eropeplus canus, Maxomys musschenbroekii, and Paruromys dominator) and the endemic tree squirrel Prosciurillus topapuensis (Durden and Beaucournu, 2000). Sigmactenus alticola pilosus (Leptopsyllidae) is also recorded from 14 other species of endemic Sulawesi murine rodents (Bunomys chrysocomus, B. prolatus, and B. karokophilus, n. sp.; Margaretamys elegans; Maxomys hellwaldii, M. wattsi, and Maxomys sp.; Melasmothrix naso and Tateomys rhinogradoides; Paruromys dominator; Taeromys celebensis and Taeromys sp.; Rattus hoffmanni and R. facetus [recorded as R. marmosurus]) and the nonnative Rattus exulans (Durden and Beaucournu, 2000). In addition to Bunomys penitus, five endemic Sulawesi murids (Rattus hoffmanni; Bunomys chrysocomus and B. karokophilus, n. sp.; Maxomys sp.; Paruromys dominator) and two nonnative rats (Rattus exulans and R. nitidus) are also hosts for Stivalius franciscae (Stivaliidae; Beaucournu and Durden, 2001). Musserella, n. gen. and species #1 (Pygiopsyllidae), resides not only on Bunomys penitus, but also on six other Sulawesi endemic murids (Bunomys chrysocomus; Rattus hoffmanni and R. marmosurus; Paruromys dominator; Maxomys sp.; Taeromys celebensis) and the nonnative Rattus exulans (Durden, in litt., 2008). Neopsylla musseri (Ctenophthalmidae) infests Bunomys penitus as well as the endemic Sulawesian Paruromys dominator and Maxomys musschenbroekii (Beaucournu and Durden, 1999). A female Macrostylophora sp. (Ceratophyllidae) that can not be identified to species was collected from a Bunomys penitus trapped on Gunung Nokilalaki (Durden and Beaucournu, 2006: 224).