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1 April 2015 A New Tree Frog of the Genus Gracixalus from Thailand (Amphibia: Rhacophoridae)
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Abstract

We report a new tree frog of the genus Gracixalus from western Thailand and describe it as a new species Gracixalus seesom based on results of morphological and molecular analyses. The new species is a small-sized Gracixalus (male snout-vent length ca. 22 mm) and is morphologically similar to G. gracilipes, but is easily distinguished from it by its dorsal tan color in life, absence of white spot on lower lip, and black markings on its foot webbing. The new species also clearly differs from all the other members of the genus by the combination of small body size, triangular snout, and light yellowish brown dorsum without distinct tuberculations. Problems of phylogeny and taxonomy of the genus Gracixalus are briefly discussed.

INTRODUCTION

From Thailand, Khonsue and Thirakhupt (2001) listed a total of 30 species of tree frogs of the family Rhacophoridae, including the following number of species: four Chirixalus Boulenger, 1893, one Nyctixalus Boulenger, 1882, four Philautus Gistel, 1848, five Polypedates Tschudi, 1838, 12 Rhacophorus Kuhl and Van Hasselt, 1822, and four Theloderma Tschudi, 1838. However, in all of these genera except for Nyctixalus and Theloderma, generic status of some species included have been changed recently. Polypedates feae (Boulenger, 1893) is now regarded as a member of Rhacophorus (see Matsui and Panha, 2006), and the four small species long placed in the genus Chirixalus were transferred to Chiromantis Peters, 1854 or Feihyla Frost, Grant, Faivovich, Bain, Haas, Haddad, de Sá, Channing, Wilkinson, Donnellan, Raxworthy, Campbell, Blotto, Moler, Drewes, Nussbaum, Lynch, Green, and Wheeler, 2006 (Frost, 2014; but see Matsui et al., 2014)

Of the remaining small species, Philautus carinensis (Boulenger, 1893) was once moved to Aquixalus Delorme, Dubois, Grosjean, and Ohler, 2005, then to Kurixalus Ye, Fei, and Dubois, 1999 (Li, et al., 2008), and now recognized as a member of Gracixalus Delorme, Dubois, Grosjean, and Ohler, 2005 (Li et al., 2009). Philautus gracilipes Bourret, 1937 was also once moved to the genus Aquixalus as the type species of its subgenus Gracixalus (Delorme et al., 2005), which is now considered as a distinct genus (Li et al., 2008). Philautus parvulus (Boulenger, 1893) was once placed in Pseudophilautus Laurent, 1943 (Li et al., 2009), but was grouped with many Indian species and moved to Raorchestes Biju, Shouche, Dubois, Dutta, and Bossuyt, 2010 (Biju et al., 2010). Rhacophorus appendiculatus (Günther, 1859) was recently moved to Kurixalus by Yu et al. (2013), while Rh. bisacculus Taylor, 1962, once placed in Aquixalus (Aquixalus) by Delorme et al. (2005), is now also considered as a member of Kurixalus (Lie al., 2008).

Most of these taxonomic changes have been made through recently developed molecular phylogenetic studies (Delorme et al., 2005; Frost et al., 2006; Li et al., 2008, 2009; Biju et al., 2010; Yu et al., 2013). As a result of these significant changes, morphologically diagnostic characters as proposed in traditional taxonomy (e.g., Liem, 1970) are nearly lacking in each of small-sized rhacophorid genera from Southern and Southeastern Asian regions. In our molecular analyses of Thai amphibians, we have already found several candidates of cryptic species (e.g., Pansook et al., 2012) and described some of them (Matsui et al., 2010; Nishikawa et al., 2013). However, there still remain many cases to be studied, and one of them is a tree frog currently identified as G. gracilipes. Close examination of its external morphology and subsequent molecular analyses revealed that it is different from all the known congeners, as we describe in detail below.

MATERIALS AND METHODS

DNA sequence data were newly obtained from tissues preserved in 99% ethanol for specimens of Gracixalus sp. from Thailand (KUHE [Graduate School of Human and Environmental Studies, Kyoto University] 35084, 35088, 35089, CU [Chulalongkorn University] K1856), G. carinensis (Boulenger, 1893) (KUHE46401, 46402), and G. jinxiuensis (Hu, 1978) (Chengdu Institute of Biology [CIB] HN201108200, KUHE 32453). We followed Kuraishi et al. (2013) for methods for DNA extraction, and amplification and sequencing of the mtDNA fragments. We deposited the resultant sequences (ca. 500 base pairs [bp] of partial sequences of mitochondrial 16S rRNA gene) in GenBank (Accession numbers listed in Table 1).

For comparisons, GenBank data of all hitherto known members of the genus, i.e., G. gracilipes, G. lumarius Rowley, Le, Dau, Hoang, and Cao, 2014, G. nonggangensis Mo, Zhang, Luo, Zhou, and Chen, 2013, G. quangi Rowley, Dau, Nguyen, Cao, and Nguyen, 2011, G. quyeti (Nguyen, Hendrix, Böhme, Vu, and Ziegler, 2008), G. supercornutus (Orlov, Ho, and Nguyen, 2004), and G. waza Nguyen, Le, Pham, Nguyen, Bonkowski, and Ziegler, 2013 were utilized. No sequence data are available for G. medogensis (Ye and Hu, 1984), which was placed in Gracixalus simply by its morphological resemblance with G. jinxiuensis (Li et al., 2009). As outgroup species, we used sequences of Rhacophorus borneensis Matsui, Shimada, and Sudin, 2013, Kurixalus eiffingeri (Boettger, 1895), K. odontotarsus (Ye and Fei, 1993), Philautus aurifasciatus (Schlegel, 1837), and Polypedates leucomystax (Gravenhorst, 1829). Details of these specimens are shown in Table 1. We followed Kuraishi et al. (2013) for tree construction and calculation of genetic distances (uncorrected p-distance).

Table 1.

Sample of Gracixalus and outgroup species used for DNA analysis (16S rRNA, 441 bp) in this study together with the information on voucher, collection locality and GenBank accession numbers. Voucher abbreviations: AMNH = American Museum of Natural History; AMS = Australian Museum; BORN = BORNEENSIS, University Malaysia, Sabah; CIB = Chengdu Institute of Biology; CUMZ = Chulalongkorn University Museum of Natural History; IEBR = Institute of Ecology and Biological Resources, Hanoi; KUHE = Graduate School of Human and Environmental Studies, Kyoto University; KIZ = Kunming Institute of Zoology; MNHN = Muséum national d'Histoire naturelle, Paris; MZB = Museum Zoologicum Bogoriense; NHMG = Natural History Museum of Guangxi; VNMN = Vietnam National Museum of Nature; VNUH = Vietnam National University, Hanoi, ZFMK = Zoologisches Forschungs-museum Alexander Koenig.

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We took the following 21 body measurements to the nearest 0.05 mm with a dial caliper under a binocular microscope, following Matsui (1984, 1994): (1) snout-vent length (SVL); (2) head length (HL); (3) head width (HW); (4) internarial distance (IND); (5) interorbital distance (IOD); (6) upper eyelid width (UEW); (7) nostril-eyelid length (N-EL); (8) snout length (SL); (9) eye length (EL); (10) eye diameter (ED); (11) tympanum diameter (TD); (12) tympanum-eye length (T-EL); (13) forelimb length (FLL); (14) lower arm and hand length (LAL); (15) first finger length (1 FL); (16) inner palmar tubercle length (IPTL); (17) hindlimb length (HLL); (18) tibia length (TL); (19) foot length (FL); (20) inner metatarsal tubercle length (IMTL); and (21) first toe length (1TOEL). Additionally, measurements were taken for finger and toe disks to the nearest 0.01 mm using a binocular dissecting microscope equipped with a micrometer: (22–25) first to fourth finger disk diameter (1-4FDW); and (26–30) first to fifth toe disk diameter (1-5TDW). We followed the system of description of toewebbing states used by Savage (1997).

SYSTEMATICS

In both the maximum-likelihood (ML: Fig. 1 A) and Bayesian (BI: Fig. 1B) trees, species of Gracixalus formed a clade, although not very strongly supported (BS = 74%, BPP = 0.98). The two trees greatly differed in the placement of G. lumarius. In ML tree (Fig. 1A), the species was nested in a clade with G. jinxiuensis, G. carinensis, G. nonggangensis, and G. waza (BS = 71%), in opposition to another clade of G. supercomutus, G. quangi, G. gracilipes, G. quyeti, and Gracixalus sp. from Thailand (BS = 90%). In contrast, in BI tree (Fig. 1B), G. lumarius was not included in the first clade (BPP = 0.95), but positioned at the base of the second group (BPP = 0.87), which did not form a clade (BPP = 0.84). Gracixalus sp. from Thailand formed a clade (BS = 100%, BPP = 1.00), and was included in the second group, although the relationships with other species were not resolved. Anyway, these results validate placement of Gracixalus sp. from Thailand in the genus Gracixalus.

Gracixalus sp. from Thailand differed genetically from the nine congeneric species by large genetic distances (5.4-15.0%: Table 2), which were larger than distances between G. quangi and G. supercomutus (2.0–2.9%) or G. gracilipes (4.2–5.4%), and between G. nonggangensis and G. waza (2.2–2.7%). Furthermore, in congruent with genetic separation, Gracixalus sp. from Thailand is clearly separated morphologically from all nominal species of Gracixalus. Thus, we conclude Gracixalus sp. from Thailand as a distinct new species and describe it as follows:

Gracixalus seesom sp. nov.
(Figs. 24)

  • Diagnosis

    The new species is assigned to the genus Gracixalus from its morphological similarity with G. gracilipes, the type species of the genus, and inclusion in the clade with the type species in the mitochondrial phylogeny. Generic diagnosis used for description of the other congeners (presence of intercalary cartilage between terminal and penultimate phalanges of digits, tips of digits expanded into large disks bearing circummarginal grooves, vomerine teeth absent, horizontal pupil, small size [males < 25 mm SVL], and triangularly pointed snout) applies to the new species, although these are not synapomorphy of the genus.

  • Gracixalus seesom sp. nov. is distinguishable from its congeners by a combination of (1) size small (males 22-23 mm, females 23-25 mm SVL), (2) snout triangularly pointed, (3) dorsal skin nearly smooth, (4) tan dorsally with orange yellow on ventral sides of limbs and anterior and posterior surfaces of thigh, (5) upper eyelid and dorsum lacking spines, (6) upper eyelid and web lacking black marking, (7) flank and ventral surface of thigh lacking brownish black spot, and (8) tibiotarsal projection absent.

  • Etymology

    The specific name is from the Thai words, “see”, meaning orangish and “som” (color), alluding to the ventral color of limbs in life of the new species.

  • Holotype

    KUHE 35084, an adult female from Pilok, Thong Pha Phum National Park, Kanchanaburi Province, Thailand (14°41′ N, 98°24′ E, 942 m a.s.l.), collected on 3 January 2002 by Masafumi Matsui and Wichase Khonsue.

  • Paratypes

    CUMZ K 1855, 1856, and two males and three females, KUHE 35085-35089, same data as the holotype. A male, KUHE 19177 from near Park HQ, Doi Inthanon National Park, Chang Mai Province, Thailand (18°31′ N, 98°32′ E, 1650 m a.s.l.), collected on 6 August 1994 by Masafumi Matsui.

  • Referred specimens

    Six males, Natural History Museum, London (BM) 1979.460–465 from Doi Inthanon, alt. 1300 m a.s.l., Chang Mai Province, Thailand.

  • Description of holotype (measurements in mm)

    Adult female, SVL 24.6 mm; body dorsoventrally compressed; head slightly longer (HL 9.3, 37.8%SVL) than wide (HW 9.0, 36.6%SVL), wider than body; snout pointed in dorsal view, rounded in lateral view, length (SL 3.7, 15.0%SVL) longer than eye length (EL 3.2, 13.0%SVL), projecting beyond mouth; canthus rostralis sharply angular; loreal region vertical and concave; nostril slightly protuberant, nearer to tip of snout (S-NL 1.4, 5.7%SVL) than to eye (N-EL 2.2, 8.9%SVL); internarial distance (IND 2.6, 10.6%SVL) less than interorbital distance (IOD 3.6, 14.6%SVL), which in turn much wider than upper eyelid (UEW 2.2, 8.9%SVL); eye large, pupil horizontal; tympanum distinct, subcircular, diameter (TD 1.2, 4.9%SVL) three-eighths of eye length and separated from eye by one-fourth of tympanum diameter (T-EL 0.3, 1.2%SVL); tympanic rim slightly elevated relative to skin of temporal region; pineal ocellus present at level connecting anterior borders of upper eyelids; vomerine teeth absent; tongue notched posteriorly.

  • Forelimb long (FLL 16.8, 68.3%SVL) and slender; hand and forearm long (LAL 13.2, 53.7%SVL); finger length formula: I < II < IV < III; expanded disks each with circummarginal groove and transverse ventral groove; disks on third and fourth fingers (3FDW 1.1, 4.5%SVL; 4FDW 1.3, 5.2%SVL) only slightly wider than those on second (2FDW I. 1, 4.5%SVL) but wider than first (1FDW 0.7, 2.9%SVL), all, but first, subequal to tympanum; remnant of webbing between inner three fingers; subarticular tubercles prominent, rounded, formula 1, 1, 2, 2; inner palmar tubercle flat (IPTL 1.1, 4.4%SVL); outer palmar tubercle weakly divided into two.

  • Hindlimb long (HLL 42.5, 172.8%SVL); tibiotarsal articulation reaching to point between nostril and eye when fully stretched leg adpressed to body; heels overlapping each other when thigh (THIGH 13.7, 55.7%SVL) and tibia (TL 14.4, 58.5%SVL) placed at right angle to body; foot (FL II. 2, 45.5%SVL) much shorter than tibia; toe length formula I < II < III < V < IV; toes bearing expanded disks each with circummarginal groove and transverse ventral groove; widths of outer toe disks (4TDW 1.3, 4.4%SVL; 5TDW 1.0, 4.1%SVL) narrower than those of outer finger disks; webbing formula I 2-2½ II 1¼-2¼ III 1½-2¾ IV2¼-1½ V; subarticular tubercles distinct, rounded, formula 1, 1, 2, 3, 2; supernumerary tubercles absent; inner metatarsal tubercle oval, (IMTL 1.0, 4.1%SVL) and flat, about two-fifths length of first toe (1TOEL 2.5, 10.2%SVL); no outer metatarsal tubercle (Fig. 4B).

  • Dorsal surface nearly smooth, sparsely scattered with minute, blunt tubercles between shoulder and sacral regions; skin of head not co-ossified to forehead; su pratympanic fold continuing as glandular fold to beyond level of axilla; skin of lower jaw posterolaterally forming short fold at anterior base of upper arm; low, large tubercles on flank, continuing to flat granules on belly; otherwise ventral surface smooth; tarsal fold absent; very weak tubercles at tibiotarsal articulation.

  • Color

    In life, dorsal surface tan, with small dark brown spots on upper eyelid and across back, forming interrupted fi01 marking (Figs. 2, 3A, 4A); faint lighter line from snout through outer margin of upper eyelid to supratympanic fold, continuing posteriorly to separate tan dorsum and darker flank (Fig. 4A); supratympanic fold margined underneath by brown, extending from eye to axilla, and covering upper threefourths of tympanum; large white blotches laterally on trunk, becoming smaller and continuing to anterior belly; small white spots less dense on translucent posterior belly; dorsal side of thigh and tibia barred with faint dark brown (Figs. 2, 3A, 4A); ventral surface of throat, chest and anterior belly opaque white; underside of forelimb, posterior to insertion of arm, and underside of hindlimb, continuing to anterior and posterior surfaces of thigh to tarsus, dorsal surface of inner four toes, and groin, bright orange (Figs. 3B, 4A); foot webbing also orange ventrally; iris golden with a network of fine black reticulations concentrated around periphery. In alcohol, dorsum faded to beige and upper eyelid covered by dark brown; ventrally totally cream white, with orange on ventral surface of limbs faded.

  • Variation

    Morphometric variation is shown in Table 3. Small sample size prohibited statistical comparisons, but in the type series, females (mean SVL ± 1 SD = 24.3 + 1.0 mm) are larger than males (22.4 ± 0.7 mm) with no overlap in SVL ranges (23.2–25.4 mm and 21.6–23.0 mm, respectively). Referenced six males in BM collection are slightly larger (22.4–24.0 mm) than paratypic males. The paratypes are generally similar with the holotype in general morphology and coloration, but some have clearer dark spots on dorsum. Males lack nuptial pads, but have a pair of vocal slits on both sides of mouth floor well anterior to jaw commissure.

  • Range

    Known only from northwestern Thailand, Pilok, Thong Pha Phum, Kanchanaburi Province and Doi Inthanon, Chiang Mai Province. The known localities vary from 942-1650 m in altitude.

  • Natural history

    At the type locality, specimens were found at night in a small valley, perching on twigs of short shrubs along a dried stream. No calls were heard in early January. Frogs found at the time of the collection of type specimens were Leptolalax melanoleucus Matsui, 2006, Limnonectes limborgi (Sclater, 1892), Limnonectes taylori Matsui, Panha, Khonsue, and Kuraishi, 2010, Kurixalus bisacculus (Taylor, 1962), and Raorchestes parvulus (Boulenger, 1893). At Doi Inthanon, Megophrys sp., Ansonia inthanon Matsui, Nabhitabhata, and Panha, 1998, Rhacophorus bipunctatus Ahl, 1927, and R. parvulus were observed with the new species.

  • Comparisons

    Gracixalus seesom sp. nov. resembles G. gracilipes from high elevations of northern Vietnam and southern China in color in preservative (beige dorsum with dark brown upper eyelid), lack of brownish black spots on flank and ventral surface of thigh, and tibiotarsal projection, but differs from it in dorsal color in life and marking on upper lip (dorsum tan in life and lacking white patch under eye vs. dorsum green in life and having white patch under eye to tympanum in G. gracilipes). The new species differs from G. supercornutus from high elevations of central Vietnam by having tan dorsum lacking large spines, and lacking white patch under eye (vs. dorsum transparent green with distinct brown markings and covered with large spines, and white patch present under eye to tympanum in G. supercornutus). Gracixalus seesom sp. nov. differs from G. quangi from medium to high elevations of north central Vietnam by having tan dorsum lacking small asperities, and lacking brownish black spots on ventral surface of thigh and tibiotarsal projection (vs. dorsum greenish to brownish green scattered with small asperities, dorsum and ventral surface of thigh with brownish black spots, and tibiotarsal projection present in G. quangi).

  • Other species of Gracixalus are different from G. seesom in coloration and snout shape. The new species having dorsum tan without tubercles, and pointed snout differs from G. quyeti from medium to high elevations of central Vietnam (vs. body brownish to moss green with a rounded snout in G. quyeti). Gracixalus seesom sp. nov. also differs from G. carinensis from high elevations of Myanmar through Thailand to northwestern Vietnam, in monotonous tan and nearly smooth dorsum, and triangular snout (vs. dorsum grayish brown with dark brown markings and snout rounded in G. carinensis). Gracixalus seesom sp. nov. overlaps in male body size with G. jinxiuensis from moderate elevations of southeastern China, high elevations of northern Vietnam, and Laos (male SVL 21–24 mm vs. 24 mm in G. jinxiuensis), but differs from it in dorsal color, snout shape, and skin structure (dorsum tan without tubercles and snout pointed vs. brown dorsum scattered with tubercles, and snout rounded in G. jinxiuensis). The new species (males 21–24 mm, snout pointed, dorsum smooth, tan in color) also differs from G. medogensis from high elevation of Xizang, China (vs. 26.5 mm, snout rounded, and dorsum brown scattered with tubercles in G. medogensis). Gracixalus seesom sp. nov. differs from G. nonggangensis from moderate elevation of Vietnamese border of China, and G. waza from moderate elevation of northern Vietnam, in body size, skin texture, and coloration (males 21–24 mm, females 23–25 mm SVL, dorsum tan without tubercles, and venter without dark spots vs. male SVL 27–36 mm, females 38 mm, dorsum greyish to moss-green with small tubercles, and venter white with brown spots in G. nonggangensis and G. waza). Finally, the new species completely differs from G. lumarius from high elevation of central Vietnam in body size and dorsal skin texture (male SVL 21–24 mm, dorsum tan and without distinct asperities vs. 39–42 mm, dorsum with distinctive, white conical asperities, and brown diurnally and yellowish brown nocturnally in G. lumarius).

  • Fig. 1.

    Maximum-likelihood (ML) (A) and Bayesian inference (BI) (B) trees from a 441 bp sequence of mitochondrial 16S rRNA gene for Gracixalus sp. from Thailand, members of the species currently assigned to Gracixalus, and for outgroups. Numbers above or below branches represent bootstrap supports for ML inferences (A) and Bayesian posterior probabilities (B).

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    Table 2.

    Uncorrected p-distances (in %) for fragment of 16S rRNA among 10 Gracixalus and five rhacophorid taxa compared.

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    Fig. 2.

    Female holotype (KUHE 35084) of Gracixalus seesom sp. nov. in life.

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    Fig. 3.

    (A) Dorsal and (B) ventral views of female holotype (KUHE 35084) of Gracixalus seesom sp. nov. in anesthetized state. Scale bar in (A) and (B) = 10 mm.

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    Fig. 4.

    (A) Lateral view of body in anesthetized state and (B) ventral view of right foot after preservation of female holotype (KUHE 35084) of Gracixalus seesom sp. nov. Scale bar in (B) = 10 mm, (A) not to scale.

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    Table 3.

    Measurements of Gracixalus seesom sp. nov. SVL (mean ± 1 SD, in mm) and medians of ratios (R) of other characters to SVL, followed by ranges in parenthesis. See text for character abbreviations.

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    DISCUSSION

    Thailand has a long history of amphibian faunal survey, and a monograph was published more than half a century ago (Taylor, 1962). However, Gracixalus gracilipes was not listed in Taylor (1962) and its occurrence in Thailand was first recorded by Chan-ard (2003: as Philautus) in an illustrated guidebook, where a map and a handwritten illustration are given. However, sources of data or the bases for identification are totally missing. Similarly, Khonsue and Thirakhupt (2001) listed the species in their checklist of Thai amphibians, but no details were given other than its general distribution range (Northern Vietnam, Yunnan P.R.C., and Thailand). Thus, nothing has been known about species of this genus within Thailand. This is probably because few herpetologists paid attention to small rhacophorids, such as this species, in Thailand.

    The type locality of the present new species, Pilok in the Thompa Phun National Park, is situated at the Myanmar border of Thailand. Although the region is not poorly surveyed and we attended there in all seasons (Khonsue, unpublished data), we encountered the new species only in early January, when there was little rain and the temperature was low. In contrast, other tree frogs like Raorchestes parvulus and Kurixalus bisacculus were observed in every occasion. Thus, the new species seems to be less abundant or has a life history different from other small tree frogs.

    Our preliminary phylogenetic analyses using only short sequences of one gene (16S rRNA) showed presence of weakly supported two genetic clades among species of Gracixalus. One clade included G. gracilipes (the type species of the genus), G. supercornutus, G. quangi, G. quyeti, and the new species, and another clade included G. carinensis, G. jinxiuensis, G. nonggangensis, and G. waza. Position of G. lumarius was enigmatic. Rowley et al. (2011) similarly used short 16S rRNA sequences and suggested the presence of two clades (Clade I and Clade II) in Gracixalus. Contents of these two clades are essentially identical with ours, although their Clade I included Gracixalus cf. jinxiuensis and Kurixalus cf. ananjevae. They reported that species in the Clade I have generally small body size (male SVL < 30 mm) and greenish dorsum, whereas those in Clade II have large body size with brownish (never greenish) dorsum and rounded snout (snout shape for Clade I not mentioned). Based on these differences, Rowley et al. (2011) suggested the separation of the genus into two distinct genera in their brief discussion. However, Nguyen et al. (2013) criticized this division by indicating similar dorsal color (yellowish-olive) of G. quyeti in Clade I and G. waza they recovered in Clade II. Gracixalus quyeti actually has a round snout unlike other members in Clade I defined by molecular phylogeny.

    Moreover, Rowley et al. (2014) added G. lumarius in their Clade I, although the species has the dorsal color and snout shape similar to members of Clade II. This again suggests incongruence between morphological and genetic characteristics in Gracixalus. Our result did not support Rowley et al.'s (2014) inclusion of G. lumarius in their Clade I. In describing this species, Rowley et al. (2014) showed only result of BI analysis and never made any definite comments. Instead they mentioned that more extensive molecular analysis would be required to resolve the evolutionary relationships within the genus. Thus, inclusion of G. lumarius in Clade I is dubious, and from large genetic distances between other species (see Table 2), even inclusion of the species in Gracixalus requires confirmation. In contrast, our results conform to Rowley et al. (2014) in recognition of very close relationship of G. nonggangensis and G. waza. These two species were described nearly simultaneously and have never been compared with each other yet. According to their original descriptions, they are very similar morphologically, and their known localities are very close. Thus, we suspect they represent a single species. If indeed this is the case, and the dates shown in the publications are correct, G. nonggangensis (Mo et al., 2013, published on line on 13 February 2013) should be synonymized with G. waza (Nguyen et al., 2013, published on line on 14 November 2012).

    It should be also noted that the species identity of G. carinensis in previous studies (Delorme et al., 2005; Li et al., 2008, 2009) and our own (in this study) is doubtful. At least Vietnamese samples we used are morphologically different from the type series of Ixalus carinensis from Myanmar (Matsui, unpublished data). An enigmatic Chinese species Philautus medogensis is now placed in Gracixalus, but this taxonomic treatment was done simply by its morphological similarity with G. jinxiuensis (Li et al., 2009) and no phylogenetic assessment has been made. In view of these facts, further analyses using long sequences for all species are required to determine the true identity and phylogenetic relationships of species now assigned to Gracixalus and related genera.

    Mode of egg deposition is an interesting problem in understanding phylogeny and evolution in the genus Gracixalus. Except for G. quyeti, whose breeding ecology is not reported (Nguyen et al., 2008), species of the Clade I of Gracixalus lays small number of eggs in a non-foamy egg mass on leaves (Fei et al., 2009; Orlov and Ho, 2004; Rowley et al., 2014), and it is most probable the new species has a similar breeding habit. Breeding habits of Rowley et al.'s (2011, 2014) Clade II (G. carinensis, G. jinxiuensis, G. nonggangensis, and G. waza) are unknown. Gracixalus lumarius is reported to breed in the tree-hole like species of Theloderma and Nyctixalus (Rowley et al., 2014). As discussed above, phylogenetic position of this species requires reexamination and longer sequence data are necessary for assessing its exact position with reference to the two clades of Gracixalus and other rhacophorid species.

    ACKNOWLEDGMENTS

    The National Research Council of Thailand and the Royal Forest Department of Thailand kindly permitted MM to conduct the project, and Chulalongkorn University kindly provided all the facilities for conducting research. MM is indebted to K. Araya for providing samples, J.-P. Jiang for supplying literaure, H. Kuraishi and H. Kawahara for laboratory assistance, and B. T. Clarke, C. McCarthy, and T. C. Nguyen for allowing him to examine specimens under their care. MM is also grateful to K. Araya, T. Chan-ard, T. Hikida, and the late J. Nabitabhata for field companionship and/or permission to conduct research. SP would like to express the gratitude to Chulalongkorn Unversity for providing some research funding, and great thanks should go to police officers at Pilok Police Station for providing accomodation to our team while doing field work at Pilok. This work was partially supported by the TRF/BIOTEC Special Program for Biodiversity Research and Training grant to WK. Field trips by MM were made possible by grants from The Monbusho (Field Research, Nos. 04041068, 06041066, 08041144, and 20405013) and TJTTP-OECF.

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    © 2015 Zoological Society of Japan
    Masafumi Matsui, Wichase Khonsue, Somsak Panha, and Koshiro Eto "A New Tree Frog of the Genus Gracixalus from Thailand (Amphibia: Rhacophoridae)," Zoological Science 32(2), 204-210, (1 April 2015). https://doi.org/10.2108/zs140238
    Received: 24 October 2014; Accepted: 1 December 2014; Published: 1 April 2015
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