Although Southeast Asia is one of the last strongholds of endangered dholes (Cuon alpinus), or Asiatic wild dogs, little is known about dhole ecology in this region. We used scat collections, prey surveys, and camera-trap data to determine the diet, prey selection, and activity of dholes in a national protected area in northern Laos. Results showed that dhole diets were dominated by ungulates (87% of biomass consumed), with additional prey including other carnivores (6%) and rodents < 1 kg (6%). Concerning individual prey species, only muntjac (Muntiacus, 45%) and sambar (Rusa unicolor, 33%) contributed >7% of biomass consumed. Dholes were not random in their consumption of ungulates, because muntjac (20–28 kg) and sambar (185 kg) were selectively consumed over medium-sized (75- to 85-kg) ungulates. Dholes were almost exclusively diurnal, and their activity pattern was significantly different (all P < 0.003) from that of all ungulate species except wild pigs (Sus scrofa). Overall, prey selection by dholes appeared to be more influenced by social behavior and terrain use of ungulates, rather than by body size or activity of ungulates. In tropical forests of northern Laos, dholes focused predation on relatively few species during diurnal hours, suggesting the management of muntjac and sambar may be important for conserving dhole populations in the region.

Wolverines are demographically vulnerable and susceptible to impacts from climate change. Their distribution is correlated with persistent spring snow cover, but food-based explanations for this relationship have not been explored. We synthesize information on the timing of both wolverine reproductive events and food availability to improve our understanding of the behaviors, habitat features, and foods that influence reproductive success. Wolverine births are constrained to a brief period of the year and occur at an earlier date than other nonhibernating, northern carnivores. Our examination suggests that this timing is adaptive because it allows wolverines to take advantage of a cold, low-productivity niche by appending the scarce resources available during winter to the brief period of summer abundance. The wolverine's bet-hedging reproductive strategy appears to require success in 2 stages. First, they must fuel lactation (February–April) with caches amassed over winter or acquisition of a sudden food bonanza (e.g., winter-killed ungulates); otherwise, early litter loss occurs. Next, they must fuel the majority of postweaning growth during the brief but relatively reliable summer period of resource abundance. The 1st stage is likely dependent on scavenged ungulate resources over most of the wolverine's range, whereas the 2nd stage varies by region. In some regions the 2nd stage may continue to be focused on scavenging ungulate remains that have been provided by larger predators. In other regions the 2nd stage may be focused on predation by wolverines on small prey or neonatal ungulates. During all seasons and regions, caching in cold, structured microsites to inhibit competition with insects, bacteria, and other scavengers is likely a critical behavioral adaptation because total food resources are relatively limited within the wolverine's niche. Habitat features that facilitate caching, e.g., boulders and low ambient temperatures, are likely important and could be related to the limits of distribution. This “refrigeration-zone” hypothesis represents a food-based explanation for the correlation between wolverine distribution and persistent spring snow cover. Understanding regional differences in foods that fuel reproduction and underlying causes to the limits of distribution could be important for maintaining wolverine populations in the future.

Ecologically similar and closely related species in sympatry may differ in their activity patterns to avoid interspecific contest competition. We here present the 1st study aimed at evaluating the effects of seasonality, group size, and presence of a congener on the activity patterns of 2 syntopic species of howler monkeys, the brown howler (Alouatta guariba clamitans) and the black-and-gold howler (A. caraya), in northeastern Argentina. During 12 months, we collected activity data on 2 groups of each species characterized by different sizes and degrees of home-range overlap, together with data on food availability. We analyzed seasonal variation in activity budgets and daily activity patterns, as well as the relationships between monthly activity budget and food availability, diet, and climate, both within and between species. Black-and-gold howlers, more clearly than brown howlers, adopted an energy-minimization strategy, reducing costly activities such as moving and traveling, during the lean season. Within each howler species, individuals in the largest group showed a greater proportion of time spent moving or traveling, or both, compared to individuals in the smallest group, suggesting the existence of within-group food competition. Juveniles of both species rested less and moved and socialized more than adults. Overall, black-and-gold howlers spent proportionately more time moving and traveling, and less time resting, probably due to their larger mean group size, than brown howlers. Daily feeding peak times diverged only slightly among groups in the lean season, but differences between groups of different species with overlapping home ranges were not larger than those among scarcely or nonoverlapping groups (of same or different species). In conclusion, even though the 2 howler species showed differences in activity patterns, mainly related to differences in their response to food seasonality, and in group size, we found no evidence of time partitioning.

The vicuña (Vicugna vicugna) is a South American camelid that has been hunted to near extinction. Following the establishment of conservation programs, vicuñas have successfully recovered to their current “Least Concern” International Union for Conservation of Nature and Natural Resources status. We analyze a 31-year vicuña census data set from northern Chile in order to investigate the influence of various factors on vicuña population dynamics. During the first 15 years, population dynamics are driven by strong growth as the population recovers from overhunting, and during the last 15 years dynamics are dominated by fluctuations around carrying capacity. We find that the best fit of the census data is a logistic growth model that takes into account how changes in rainfall and primary productivity lead to fluctuations in carrying capacity, suggesting that the resources limiting vicuña population size are not constant but change over time. We also find that the spatial distribution of vicuñas changes over time with respect to the nutrient-rich bofedales (Andean peatlands). Our study demonstrates the importance of collecting and analyzing long-term census data, and suggests that further insight could be gained if vicuña location with respect to habitat type was recorded during the census.

Temporal partitioning of activity among sympatric species can be an important mechanism for species coexistence. Further, if exotic and native species overlap temporally, there is potential for direct competition and antagonism, which may lead to native species extirpation. We 1st assessed if ecologically similar native carnivores of Madagascar demonstrated activity pattern overlap and then explored whether overlap in activity might lead to negative impacts of exotic carnivores on native carnivores. We used photographic sampling to quantify the temporal activity patterns of carnivores at 4 study sites. The activity of the 2 smaller-bodied native species, Galidia elegans and Galidictis fasciata, overlapped minimally; these 2 carnivores share a similar generalist diet, which may drive their divergent temporal activity. In contrast, the medium-sized native species, Fossa fossana and Eupleres goudotii, were both highly nocturnal; these 2 species appear segregated in their diets. The largest native carnivore, Cryptoprocta ferox, selectively used crepuscular hours, but overall was cathemeral; it was notably absent or basically so at sites where dogs were most abundant and active throughout the diel cycle. We found G. elegans to shift from preferred activity periods in the presence of dogs and the exotic Viverricula indica. Our results suggest that the presence and activity of exotic carnivores can negatively impact native carnivores in fragmented rain forests.

Scale influences habitat selection. We used data from 30 global positioning system radiocollared lions (Panthera leo) collected between 2003 and 2007 in Hwange National Park, Zimbabwe, and information from 227 locations where lions had made kills, to assess how lions select habitat at 3rd-order habitat selection (selection of habitats within home ranges) and 4th-order habitat selection (selection of kill sites within the habitats used). Within home range, lions preferentially selected bushed grasslands and sites close to water holes, which are both characterized by high prey abundance. However, lions preferentially killed in thickets, where prey abundance was not the highest but where prey catchability may be higher because of dense vegetation. Our results support the suggestion that there are different determinants of habitat selection at different scales with prey abundance being the main driver of habitat selection at 3rd-order and prey catchability the main driver at 4rth-order habitat selection.

We modeled the growth in skull size of brown bears (Ursus arctos) using 11,651 individuals across 6 regions in Alaska with the von Bertalanffy function. The study areas varied greatly in habitat types and included coastal areas in south-central Alaska, interior regions, and the most northern reaches of the species' North American range. The top-ranking model supported region- and sex-specific growth curves. The large differences in parameter estimates of asymptotic size and the growth coefficient across regions were likely influenced by variation in habitat quality, especially the availability of salmon (Oncorhynchus spp.), and these differences relate to other known life-history traits. Contrary to other studies of North American bears, we found a strong hyperallometric relationship in sexual size dimorphism (SSD) where SSD increased with asymptotic size. This relationship supports sexual selection as the driving mechanism of SSD in brown bears. However, the variable intensity of sexual selection across these regions, as demonstrated through hyperallometry in SSD, is likely influenced by proximate factors such as variable food resources and population densities that vary by more than 2 orders of magnitude. The ecological implications of the variation in growth, size, and SSD of brown bears across their Alaskan range are substantial and need to be recognized and incorporated into area-specific management and conservation strategies.

The metabolic rate–body size relationship suggests that the African elephant (Loxodonta africana) should be least selective among mammalian herbivores in its diet. However, selection among plant species needs to be distinguished from selection for plant parts or other features. We investigated seasonal variation in the selective utilization and dietary contribution of woody plant species, parts, and height classes to vegetation consumed by elephants in the Kalahari sandveld region of Chobe National Park, Botswana. Only 30% of 27 common woody species were moderately or highly acceptable to elephants in the wet season, increasing to more than 50% in the hot dry season. Six woody species remained mostly or entirely rejected by elephants throughout the year. Most of the browse consumed during each season came from 1 or 2 common shrub species. Leaves and leaf-bearing shoots constituted 80% of the material consumed from woody plants during the wet season, but only 45% during the cool dry season. Stem, bark, and root tissues contributed 50% of the woody plant component of the diet in the cool dry season, increasing to 94% in the hot dry season. Hence, despite their narrow selection for plant species, large size coupled with hindgut digestion enables elephants to exploit a wide range of plant parts, including fibrous stems, bark, and roots. Accordingly, elephants occupy a dietary niche distinct from browsing or grazing ruminants.

Extent of edge habitat is often defined arbitrarily from a boundary between 2 habitats. Instead, we assessed whether space use by white-footed mice (Peromyscus leucopus) responded to habitat changes along an edge-to-interior gradient in eastern deciduous forest. We measured movement distance as mean squared distance from center of activity (MSD), microhabitat variables, and distance to nearest conspecific neighbor. Distance of center of activity from the habitat edge was not affected by animal age (e.g., body mass). Male MSD did not change along the habitat gradient. Female MSD increased with distance from habitat edge, was negatively related to vertical cover, and was positively related to diameter at breast height of trees. Increased MSD in forest interior may reflect lower availability of nesting sites or diet items. Decreased MSD at forest edge may reflect higher vegetative cover that provided more food or behaviors by mice to avoid edge predators/parasites. Female use of vertical habitat increased with distance from habitat edge, and was related to fewer trees, less woody debris, and smaller distance to nearest conspecific neighbor. Fewer trees and less woody debris could negatively affect availability of nesting sites, travel routes, or diet items, hence greater use of vertical habitat. The nearest-neighbor effect may indicate intraspecific competition from lower availability of resources in forest interiors. Such responses in space use along a habitat gradient indicated that defining edge habitat as an arbitrary distance from a habitat edge may be insufficient to understand ecology and behavior of small mammals.

We radiotracked 16 (6 males, 10 females) adult Molina's hog-nosed skunks (Conepatus chinga) to examine habitat selection using compositional analysis at 2 spatial scales in a protected area and a landscape fragmented by agriculture. To aid in understanding the habitat use of skunks, the abundance of invertebrates was estimated in each habitat. Habitat use and selection varied between the 2 study sites. Skunks selected habitat at landscape level but not at home range level in the protected area. In the cropland area skunks showed overall habitat selection at both scales, although at landscape level we did not detect a significant ranking of habitats. In both sites, when we found a significant selection grassland patches ranked first. Although this habitat does not reach 10% of the total area, it presented the highest abundance of Coleoptera. Because Coleoptera are the main prey item of this mephitid, these results support the hypothesis that habitat selection in C. chinga is highly related to food availability. We conclude that the preservation of grassland patches may be essential for managing C. chinga populations in the highly human-modified landscapes of the Pampas.

Territoriality in animals is of both theoretical and conservation interest. Animals are territorial when benefits of exclusive access to a limiting resource outweigh costs of maintaining and defending it. The size of territories can be considered a function of ecological factors that affect this benefit–cost ratio. Previous research has shown that territory sizes for wolves (Canis lupus) are largely determined by available biomass of prey, and possibly pack size and density of neighboring wolf packs, but has not been interpreted in a benefit–cost framework. Such a framework is relevant for wolves living in the Northern Rocky Mountains where conflicts with humans increase mortality, thereby potentially increasing costs of being territorial and using prey resources located near humans. We estimated territory sizes for 38 wolf packs in Montana from 2008 to 2009 using 90% adaptive kernels. We then created generalized linear models (GLMs) representing combinations of ecological factors hypothesized to affect the territory sizes of wolf packs. Our top GLM, which had good model fit (R²  =  0.68, P < 0.0005), suggested that territory sizes of wolves in Montana were positively related to terrain ruggedness, lethal controls, and human density and negatively related to number of surrounding packs relative to the size of the territory. We found that the top GLM successfully predicted territory sizes (R²  =  0.53, P < 0.0005) using a jackknife approach. Our study shows that territory sizes of group-living carnivores are influenced by not only intraspecific competition and availability of limiting resources, but also by anthropogenic threats to the group's survival, which could have important consequences where these territorial carnivores come into conflict with humans.

Coyotes (Canis latrans) occur across North America in many types of ecosystems, including urban areas, yet certain aspects of coyote behavior remain obscure. Previous observational studies have provided evidence that coyotes are socially monogamous; however, the degree to which coyotes exhibit genetic monogamy has not previously been determined. We used radiotelemetry and genetic techniques to determine the mating system of an urban coyote population. We obtained samples from 236 coyotes captured during 2000–2006 in the Greater Chicago Metropolitan Area of Illinois. Individuals were genotyped using 12 polymorphic microsatellite markers. Among 18 litters comprising 96 offspring, we found no evidence of polygamy, and detected a single instance of a double litter (pups from different parents sharing the same den). The 2 mated pairs that contributed to the double litter had not interbred. However, the relatedness values shared between 1 mated pair and the pups that were not their offspring suggested that they were closely related, possibly as cousins or grandparents/grandoffspring. Across all radiocollared mated pairs, mean home range overlap for the male and female was 80.1% (SD  =  13.4). Among 7 mated pairs, 3 of which were radiotracked over multiple years, there was no evidence of mate abandonment and multiyear monogamy was maintained. Despite the high food resources available and high population density, urban coyotes display no variability in their monogamous mating system.

We used monthly capture–mark–recapture information to determine growth rates and life spans for 2 populations of meadow voles studied for 28 and 29 months in eastern Virginia in order to learn whether the exceptionally large body masses of some voles were due to rapid growth, long lives, or both. On 1 study grid, 64 males (19%) and 43 nonpregnant females (11%) were ≥70 g, with the largest male being 89 g. Mostly positive growth rates (averaging 1.1–3.9 g/month) were recorded, even in autumn and winter months, times when meadow voles are losing mass in northern populations, where most studies of body growth have been conducted. Periods of low mean body mass were associated with low population density more than high body mass was associated with high population density. Patterns of body mass dynamics were related more to season than to density in our populations. We concluded that the large body masses we observed in some voles were due more to long field lives than to unusually high rates of body growth.

Golden-mantled ground squirrels (Callospermophilus lateralis) have been subjects of laboratory investigations of hibernation for many years. As such, patterns of torpor for this species have been well characterized under laboratory conditions but not during natural hibernation. The purpose of this study was to determine torpor patterns of free-living C. lateralis and to correlate these patterns with the sex, age, and reproductive status of each animal, as well as environmental conditions. We surgically implanted body temperature (T_b) data loggers into the abdominal cavities of animals in late summer 2008 and 2009. In spring 2009 and 2010, animals were recaptured and loggers were removed. During hibernation, animals displayed mean (± SEM) torpor bout lengths from 8 to 14 (± 0.3) days with maximum duration of 21 days, and minimum T_b of 0°C ± 1°C. Adult males entered hibernation later, emerged earlier, spent less time in torpor, and had fewer multiday torpor bouts than either females or juvenile males. These results suggest that torpor patterns in naturally hibernating C. lateralis are influenced by sex and reproductive status.

The Columbia Basin pygmy rabbit (Brachylagus idahoensis) is critically endangered and the focus of a captive-breeding program. However, reproductive success in captivity to date has not been sufficient to sustain reintroduction efforts. The goal of this study was to investigate patterns of fecal progestagen and glucocorticoid excretion in females during mating, gestation, and lactation and identify hormonal relationships to reproductive success. Fresh fecal samples were collected from 48 adult, female rabbits over 3 breeding seasons at a frequency of 4–7 samples per week. Results showed that a large (17-fold) increase in progestagen concentrations 1 day after mating provides a reliable means of determining if a successful mating occurred. In general, higher glucocorticoid concentrations during the breeding season, specifically during mating and gestation, were associated with lower reproductive success. Females that failed to conceive during the breeding season had higher glucocorticoid and lower progestagen baseline concentrations than females that did conceive. Glucocorticoid excretion during late gestation, but not lactation, was negatively associated with litter success, suggesting it affects offspring survival more during the prenatal than the postnatal period. Progestagen and glucocorticoid concentrations at the end of gestation were positively related to litter size, which may be an important factor in juvenile survival. In summary, higher concentrations of fecal glucocorticoids during the breeding season were associated with reduced conception rates and survival of subsequent litters. Ultimately, identifying what factors cause elevated glucocorticoids in pygmy rabbits could provide opportunities to alleviate negative stressors and increase the reproductive output of the captive population.

We examined the effects of season and captivity on several commonly measured physiological variables (body temperature, metabolic rate, thermal conductance, and evaporative water loss [EWL]) for the numbat (Myrmecobius fasciatus), an endangered myrmecophagous Australian marsupial, because the maintenance of a wild-type physiology may increase the likelihood of successful reintroduction of numbats into the wild. Our results indicate that the physiology of male captive numbats is representative of wild individuals, at least at thermoneutrality, except for some diet-related effects on substrate metabolism and thermoregulation. Season significantly influenced physiological variables, in particular basal metabolic rate (BMR) and EWL. BMR was 30–37% higher in winter than in summer, and EWL increased at a high ambient temperature (T_a) in winter, presumably reflecting seasonal differences in T_a, food availability, and water consumption. Seasonal variation in physiological responses of captive numbats was similar to that observed for wild numbats. We conclude that there is seasonal flexibility in the physiology of numbats, and that captivity under seminatural conditions does not compromise their basic physiology.

Nutritional condition is an important determinant of productivity and survival in caribou (Rangifer tarandus). We used samples of excreta (n  =  1,150) to estimate diet composition from microhistology and 2 isotopic proxies of protein status for 2 ecotypes of caribou in 4 herds in late winter (2006–2008). Isotopes of nitrogen (δ¹⁵N in parts per thousand [‰]) from excreta samples (urea, diet, and body N) were used to estimate indexes of protein status: the proportion of urea N derived from body N (p-UN) and the difference between the δ¹⁵N of the body and urinary urea (Δ_body-urea). We examined dietary and terrain characteristics, δ¹⁵N, p-UN, and Δ_body-urea by ecotype, herd, year, and foraging site. Multiple regression and an information-theoretic approach were used to evaluate correlates of protein status at each foraging site. The dietary and terrain characteristics of foraging sites did not vary by ecotype or herd (P > 0.108); diets were dominated by lichens (68% ± 14.1% SD). The δ¹⁵N of urea, diet, body N, p-UN, and Δ_body-urea varied among foraging sites within each herd (P < 0.001). Although highly variable, the δ¹⁵N of urinary urea was typically low (−4.68‰ ± 2.67‰ SD). Dietary N also had low δ¹⁵N (−4.18‰ ± 0.92‰ SD), whereas body N was generally heavier in ¹⁵N (2.20‰ ± 1.56‰ SD) than urinary urea or the diet. Both measures of protein status were similarly diverse between ecotypes and among herds, which limited their applicability to monitor protein status at the population level. Although we observed limitations to interpreting estimates of p-UN from highly vagile ungulates, the Δ_body-urea may prove to be a useful index of protein status at smaller spatial and temporal scales. Indeed, a portion of the observed variance (r²  =  0.26) in Δ_body-urea at each foraging site was explained by the proportion of shrubs in the winter diet. There remains potential in using δ¹⁵N in excreta as a noninvasive tool for evaluating protein status in northern ungulates; however, considerable analytical and sampling challenges remain for applying these isotopic approaches at large scales.

Track tubes may help measure impacts of disturbances on small mammals by providing information about the magnitude and timing of fluctuations in relative abundance. We evaluated live-capture and track-tube data from 8 trapping grids to test the utility of track tubes for monitoring abundance of beach mice (Peromyscus polionotus) through time and for comparing relative abundance of beach mice among sites. When averaged across grid sites, track indexes and abundance estimates exhibited strong covariation through time. Associations between the track index and estimated abundance on different grids varied from strong to very poor depending on sample period. Associations between track indexes and abundance estimates were strong when mouse densities on all grids were relatively low, but they were weak during other sample periods when densities were highly variable among grids. This study points to the need to understand factors that influence the relationship between indexes from track tubes and mouse abundance before track tubes can be used to compare abundances among sites.

We studied the population structure of 3 species in the Myotis mystacinus complex (M. mystacinus, M. brandtii, and M. alcathoe) during the swarming period by sampling bats at 27 caves in the Carpathian Mountains and adjacent areas in southern Poland using 14 or 15 nuclear microsatellite loci. None of the examined species were in Hardy–Weinberg equilibrium following the global test for heterozygote deficiency. Inbreeding coefficient (F_IS) values at the species level also were statistically greater than zero. This may indicate some level of inbreeding in all examined taxa although it seems to be relatively low because significant F_IS values were recorded in only 2 swarming sites of M. mystacinus, 2 sites of M. brandtii, and 3 sites of M. alcathoe. However, almost 10% of related individuals sharing 1 parent (i.e., half siblings) were found in the same swarming sites for M. mystacinus and M. brandtii, with fewer observed in M. alcathoe. At the population level, 4.1%, 5.9%, and 8.7% of individuals of M. mystacinus, M. brandtii, and M. alcathoe, respectively, were assigned as full siblings. These figures suggest the possibility of females mating selectively with the same male in more than 1 year.

Deciduous teeth of Carnivoramorpha can differ substantially from their permanent structural and functional counterparts, particularly dP4. As a consequence, isolated carnivoramorphan deciduous teeth have repeatedly been misidentified as permanent teeth of different, often unrelated taxa. Due in part to this potential for misidentification, the deciduous dentitions of basal carnivoramorphans remain poorly documented. This study describes and illustrates the 1st known deciduous premolars of a member of the basal carnivoramorphan family Viverravidae, with dP3–4 and dp3–4 of the early Eocene Didymictis protenus (Cope, 1874) documented by specimens associated with permanent teeth. The morphology of these specimens permits a reconsideration of the affinities of 2 mid-Paleocene taxa, Deltatherium durini Van Valen, 1978 and Prolimnocyon macfaddeni Rigby, 1980, that have been proposed to represent the earliest known members of the family Hyaenodontidae and the order “Creodonta.” Both species are founded on viverravid deciduous premolars. Reidentification of these taxa eliminates the Paleocene record of hyaenodontids from North America.

We examined, in the context of phylogeny, variations in ventral cranial shape in Martino's vole (Dinaromys bogdanovi), a rare rodent endemic to the western Balkans. Our analysis was based on 138 complete adult skulls, which were pooled into 3 phylogeographic groups (Northwestern, Central, and Southeastern). These groups were retrieved in an earlier study based on a 555–base-pair fragment of mitochondrial cytochrome b gene, which suggested a stepping-stone pattern of southward expansion followed by allopatry. Ventral skull shape was analyzed with geometric morphometrics using 23 two-dimensional landmarks. The primary shape differences across groups are the sizes of the auditory bulla and the foramen magnum, the length of the incisive foramen, and the width of the rostrum. Consistent geographic trends in shape changes were rare, and size was stable across phylogeographic groups. Morphological relationships among groups closely resemble genetic distances, implying their neutral evolution rate. We suggest that the adaptive zone occupied by Martino's vole imposes narrow limits to its phenotypic variation. Under the strong pressures of stabilizing selection for the normative (intermediate) phenotype, random drift in isolated populations produced only minor deviations in the ventral cranium.

The San Bernardino shrew, Sorex obscurus parvidens Jackson, 1921, is a population inhabiting the San Bernardino and San Gabriel mountains of southern California. For the past 9 decades, this population has been considered either a subspecies of S. obscurus Merriam, 1895, S. vagrans Baird, 1857, or S. monticola Merriam, 1890; or an undifferentiated population of S. ornatus Merriam, 1895. Aside from the changing taxonomic landscape that contextualizes the genus Sorex, previous study of S. obscurus parvidens has been retarded by the perception of limited available samples (typically, fewer than 8 specimens); misinterpretation of the provenance of specimens identified as S. obscurus parvidens; misunderstanding of the type locality; and inclusion of specimens of this taxon in the type series of another species with which S. obscurus parvidens has been both contrasted and allied at different times. My investigation of S. obscurus parvidens indicates that it is a distinctive population that is morphologically closest to S. ornatus, and it corresponds to the Southern Clade of that species. However, the appropriate names for deep clades within S. ornatus remain uncertain. Until this uncertainty is resolved, S. obscurus parvidens should be considered a distinctive population within S. ornatus; for conservation purposes, it should be recognized as S. ornatus parvidens.

A new species of talpine mole from northern Vietnam is described and compared with other species of the genus Euroscaptor. This small mole was assigned to the genus Euroscaptor on the basis of its dental formula, but it also shows unique morphological and karyological characteristics. The new species is externally similar to E. parvidens from southern Vietnam, possessing warty protuberances on the muzzle not seen in other members of this genus. The tail of the new species is much shorter than in E. parvidens and E. malayana, both known to have short tails. The tail is not visible under the fur in the dorsal view, giving it an almost tailless appearance. The skull of the new species is similar to that of E. longirostris, but the palate is characteristically wider. The molars of the upper jaw are of a simple triangular shape, and there is no hypoconulid in the lower molars. The diploid number of the new species was determined to be 2n  =  38, which is a new karyotype for this genus. This mole inhabits the lower elevational areas of northern Vietnam and is partially peripatric with E. longirostris in the type locality. Because of the distribution of another taxon in northern Vietnam, Mogera latouchei, the ecological relationships among 4 species of Vietnamese moles also is discussed.

We expand upon recent studies on relationships within the Oryzomyini, in particular, those involving taxa currently assigned to the genus Sigmodontomys. In recent years, Sigmodontomys has been treated as including 2 species, alfari (J. A. Allen, 1897) and aphrastus (Harris, 1932), but throughout their complicated taxonomic history both species also have been placed in the genus Oryzomys, and alfari independently in Nectomys. Using morphological (98 external, cranial, dental, and postcranial) and molecular (nuclear interphotoreceptor retinoid–binding protein gene and mitochondrial cytochrome-b and ribosomal 12S RNA genes) characters, we infer the phylogenetic position of these 2 species within Oryzomyini. We document that alfari and aphrastus do not form a monophyletic group. Sigmodontomys alfari is most closely related to Melanomys, and aphrastus is either the sister to that clade, or to the extinct Caribbean genus Megalomys. Thus, aphrastus is best regarded as representing a new genus, which is described and named herein. This new genus falls within the Sigmodontomys–Melanomys–Aegialomys–Nesoryzomys clade, which forms a monophyletic group of mainly southern Central American and northern South American taxa primarily restricted to lowland to midelevation montane trans-Andean habitats and possessing a marked ability to cross expanses of salt water. The new genus occurs at middle elevations from north-central Costa Rica to northwestern Ecuador and along with some populations of Aegialomys and Melanomys occupies the highest elevations for members of this group.