Raorchestes dulongensis, Wu & Liu & Gao & Wang & Li & Zhou & Yuan & Che, 2021

Wu, Yun-He, Liu, Xiao-Long, Gao, Wei, Wang, Yu-Fan, Li, Ying-Chun, Zhou, Wei-Wei, Yuan, Zhi-Yong & Che, Jing, 2021, Description of a new species of Bush frog (Anura: Rhacophoridae: Raorchestes) from northwestern Yunnan, China, Zootaxa 4941 (2), pp. 239-258 : 246-252

Raorchestes dulongensis sp. nov.

Fig. 4 ; Table 2.

Holotype. KIZ 035082 , an adult male collected from Qinlangdang Village , Derung-Nu Autonomous County Gongshan , Nujiang Lisu Autonomous Prefecture, Yunnan Province, China (N 27.67°, E 98.27°; elevation 1218.0 m a.s.l.), collected by Zhi-Yong Yuan and Xiao-Long Liu on 12, July, 2019.

Paratypes. Two males KIZ 035125 and KIZ 035126 , collected at the same locality and same collection information as the holotype .

Etymology. The specific epithet “dulongensis” is given as a noun in apposition and refers to the name of the Dulong River of China–located in Yunnan Province, China, where the new species occurs.

Diagnosis. The Raorchestes dulongensis sp. nov. is assigned to the genus Raorchestes by its molecular phylogenetic position and the following morphological characters: small sized frogs; vomerine teeth absent; active at night; tips of all fingers and toes expanded into discs having circummarginal grooves. It is distinguished from geographically and molecularly relevant congeners by the following combination of characters: (1) a small-sized species with 15.0–19.0 mm SVL in adult males (n=3); (2) tympanum distinct; (3) vomerine teeth absent; (4) tongue pyriform, notched posteriorly; (5) tips of all fingers and toes with well-developed disks, with distinct circummarginal grooves; (6) webbing between fingers absent; (7) rudimentary webbing between toes; (8) fingers and toes with narrow lateral dermal fringes; (9) tibiotarsal articulation reaching anterior of eye when hindlimb is stretched along the side of the body; (10) the heels slightly overlapping when legs are held at right angles to the body; (11) relative finger lengths: I <II <IV <III, relative toe lengths: I <II <V <III <IV; (12) inner metatarsal tubercle oval, outer metatarsal tubercle absent; (13) supratympanic fold distinct; (14) finger discs and toe discs greyish or orange; (15) flank near the crotch with a distinct black region between two creamy white patches, and the thigh having a similar black patch near the groin, proximal to another creamy white patch; (16) a distinct “) (”-shaped dark marking on the back; (17) male with external single subgular vocal sac; (18) nuptial pad absent.

Description of holotype (measurements in mm; provided in Table 2): KIZ 035082, sexually mature male, body habitus stocky ( Fig. 4 ), a small size frog (SVL = 15.0), head slightly longer (HDL/SVL 38.7%) than wide (HDW/SVL 36.7%), HDW/HDL ratio 94.8%; canthus rostralis rounded, loreal region slightly concave; top of head relatively flat; snout obtusely pointed in dorsal view and rounded in profile, projecting beyond lower jaw; nostril closer to anterior corner of eyes than tip of snout (DNE/SN 76.9%); tympanum distinct, relatively small (TD/HDL 17.2%); eye diameter notably larger than tympanum diameter (ED/TD 230.0%); eye diameter equal to snout length (ED/SNT 100.0%); vomerine teeth absent; tongue pyriform, notched posteriorly; internasal distance narrower than interorbital distance (IND/IOD 85.0%), which is broader than upper eyelid width (IND/UEW 130.8%); interorbital distance between posterior margins of eyes 2.0 times that of anterior margins (IFE = 2.4; IBE = 4.9); supratympanic fold broad, from posterior corner of the eye to above the forearm; pupil oval, horizontal.

Forelimb and hand length (8.0) longer than half body size (FHL/SVL 53.3%); forelimb length shorter than hand length (FAL/HL 84.1%); relative finger length: I <II <IV <III (FLI = 1.1; FLII = 1.8; FLIII = 2.8; FLIV = 1.9); tips of all four fingers with well-developed disks, with distinct circummarginal grooves; lateral dermal fringes on fingers, narrow; webbing between fingers absent; subarticular tubercles prominent, rounded, formula: 1, 1, 1, 1; supernumerary tubercles absent; inner and outer metacarpal tubercles present; nuptial pad absent ( Fig. 4E ).

Hindlimbs moderately long, tibia length distinctly shorter (TL/SVL 48.7%) than thigh length (THL/SVL 50.0%), TL/THL ratio 97.3%, but greater than foot length (FL/SVL 38.0%), TL/FL ratio 128.1%; tibiotarsal articulation reaching anterior of the eye when hindlimb is stretched along the side of the body; the heels slightly overlapping when legs are held at right angles to the body; relative toe lengths: I <II <V <III <IV (TLI = 1.3; TLII = 1.5, TLIII = 2.3; TLIV = 3.3; TLV = 2.0); tips of all toes expanded to well-developed discs with circummarginal grooves; subarticular tubercles distinct, rounded, formula: 1, 1, 1, 2, 1; supernumerary tubercles absent; narrow dermal fringe present on all toes; rudimentary webbing between toes; inner metatarsal tubercle oval, outer metatarsal tubercle absent ( Fig. 4F ).

Dorsum, dorsal surface of limbs, snout, between eyes, and upper eyelid shagreened with numerous tubercles; throat, chest, and ventral surfaces of forelimbs smooth; flanks of body relatively smooth and scattered with sparse granules; surfaces of hands and feet smooth; dorsolateral folds absent ( Fig. 4 ).

Color of the holotype in life. For coloration of the holotype in life see Fig 4 . Dorsal color brown, with a distinct dark triangular marking between the eyes; a distinct “) (”-shaped dark marking on the back; finger discs and toe discs greyish or orange; ventral surface of the throat, chest, and belly opaque creamy white, with a lot of white spots; flank near the crotch with a distinct black region between two creamy white patches, and the thigh having a similar black patch near the groin, proximal to another creamy white patch; dorsal parts of limbs with dark brown crossbars; dorsal surface of the fingers and toes with more or less distinct dark brown crossbars; ventral surface of the thighs, tibia, and tarsus brown with many large creamy white patches and with many small white dots; iris golden brown; dark lower margin of supratympanic fold.

Male secondary sexual characteristics. Male has external single subgular vocal sac with slit-like openings at posterior corners of jaws.

Distribution and ecology. Raorchestes dulongensis sp. nov. is known only from a single locality, Qinlangdang Village, Derung-Nu Autonomous County Gongshan, Nujiang Lisu Autonomous Prefecture, Yunnan Province, China (N 27.67°, E 98.27°). All individuals were found in elevations of 1218.0 m a.s.l. in shrubs and herbs on either side of the road between 22:00 and 23:30 ( Fig. 5 ). The males were actively calling at night and no calling during the daytime. Phonetically, the advertisement call sounds like ‘treenk.. ...treenk.. ...treenk...’, however they vary in call duration and inter-call interval duration. But it is difficult to locate due to its small size and occurrence in the subcanopy. This species is sympatrically distributed with Zhangixalus burmanus and Duttaphrynus cyphosus .

Comparisons. Geographically, the new species is found in Derung-Nu Autonomous County Gongshan, Yunnan Province, China, which belong to SEA-SC, Himalayas, and northeastern India. Comparative data of Raorchestes dulongensis sp. nov. with these Raorchestes species distributed in these regions are listed in Table 3. Phylogenetically, the matrilineal genealogy assigns Raorchestes dulongensis sp. nov. to Clade A1, which occurs in SEA-SC, eastern Himalayas, north-Western Ghats, and northeastern India. Unrelated Clade A1, distributed in the eastern Himalayas and northeastern India ( Raorchestes taxa) are omitted from comparisons for simplicity. In addition, before Buji et al. (2010) established the genus Raorchestes , most of the members of Raochestes were all placed under the genus Philautus . However, there are currently four species of the genus Philautus ( P. garo , P. kempiae , P. kempii , and P. namdaphaensis ) whose systematic positions are not yet determined and were also described from the vicinity of the type locality of the new species. Thus, we compared Raorchestes dulongensis sp. nov. to all other recognized species of Raorchestes from clade A1, species distributed in northeast India and the eastern Himalayan region, and four Philautus species with uncertain taxonomic status, which include R. andersoni , R. cangyuanensis , R. gryllus R. longchuanensis , R. menglaensis , R. parvulus , R. rezakhani , R. ghatei , R. tuberohumerus , R. bombayensis , R. leucolatus , R. shillongensis , R. manipurensis R. sahai , R. annandalii , P. garo , P. kempiae , P. kempii , and P. namdaphaensis ( Anderson et al. 1878; Boulenger 1906; Annandale 1912; Boulenger 1919; Smith 1924; Pillai & Chanda 1973; Yang et al. 1978; Sarkar & Sanyal 1985; Kou 1990; Bossuyt & Dubois 2001; Kuramoto & Joshy 2003; Sarkar & Ray 2006; Fei et al. 2009; Mathew & Sen 2009; Fei et al. 2012; Seshadri et al. 2012; Padhye et al. 2013; Vijayakumar et al. 2014; Wu et al. 2019; Al-Razi et al. 2020).

Raorchestes dulongensis sp. nov. is significantly different from R. gryllus , which according to the phylogenetic tree appears to be most closely related (although their relationships are not strongly supported), by SVL of adult male 15.0–19.0 mm (vs. 25.0–27.0 mm in R. gryllus ), head longer than wide (vs. head wider than long in R. gryllus ), tympanum distinct (vs. tympanum indistinct in R. gryllus ), webbing between fingers absent (vs. a rudiment of a web between the two outer in R. gryllus ), rudimentary webbing between toes (vs. a little more than half webbed in R. gryllus ), and outer metatarsal tubercle absent (vs. present in R. gryllus ).

The new species is different from the remaining SEA-SC species ( Table 3). Raorchestes dulongensis sp. nov. shares with R. menglaensis the following morphological features: a similar body size, the color pattern, dorsal surface with a dark") ("-shaped marking, inner and outer metacarpal tubercles present, and finger webbing absent, but differs consistently in male with external single subgular vocal sac (vs. internal single subgular vocal sac in adult males of R. menglaensis ), in all fingers and toes with narrow lateral dermal fringes (vs. absent in R. menglaensis ), in nuptial pad absent (vs. white nuptial pad at the base of the first and second finger in R. menglaensis ), and in finger discs and toe discs greyish or orange (vs. not orange in R. menglaensis ); Raorchestes dulongensis sp. nov. shares with R. longchuanesis the following morphological features: a similar body size, external single subgular vocal sac, tympanum distinct, the crotch with a distinct black patch, finger discs and toe discs orange, and finger webbing absent, but differs consistently in narrow lateral dermal fringes on all fingers and toes (vs. only on the first and second fingers with lateral dermal fringes, in lateral dermal fringes of toes absent in R. longchuanesis ), in rudimentary webbing between toes (vs. 1/4 webbing R. longchuanesis ), in nuptial pad absent (vs. grayish-white nuptial pad at the base of the first finger in R. longchuanesis ), and in iris golden brown (vs. reddish brown in R. longchuanesis ); Raorchestes dulongensis sp. nov. shares with R. cangyuanensis the following morphological features: a similar body size, external single subgular vocal sac, dorsal surface with a dark") ("-shaped marking, inner and outer metacarpal tubercles present, but differs consistently in presence of tympanum (vs. tympanum indistinct in R. cangyuanensis ), in absence of nuptial pads (vs. reddish nuptial pad at the base of the first finger in R. cangyuanensis ), in flank near the crotch with a distinct black region between two creamy white patches, and in the thigh having a similar black patch near the groin, proximal to another creamy white patch (vs. flank near the crotch with a distinct black region bordering a large creamy white patch, and the thigh orange having two similar black region near the groin in R. cangyuanensis ), and in ventral surface of thighs, tibia, and in tarsus brown with many large creamy white patches and with many small white dots (vs. ventral surface body and limbs brown, with small black and white spots in R. cangyuanensis ); Raorchestes dulongensis sp. nov. shares with R. parvulus the following morphological features: a similar body size, supratympanic fold distinct, webbing absent between fingers, inner and outer metacarpal tubercles present, but differs consistently in the absence of supernumerary tubercles (vs. present on third finger in R. parvulus ), in subarticular tubercles distinct, rounded, formula: 1, 1, 1, 2, 1 (vs. prominent, formula 1, 1, 2, 2, 1 in R. parvulus ), in tibiotarsal articulation reaching anterior of eye (vs. the tibiotarsal articulation reaching the posterior border of the eye in R. parvulus ), in rudimentary webbing between toes (vs. the webbing present, medium in R. parvulus ), and in relative toe lengths I <II <V <III <IV (vs. relative length of toes: I <II <III <V <IV in R. parvulus ); Raorchestes dulongensis sp. nov. shares with R. andersonii the following morphological features: a similar body size, the color pattern, the crotch with a distinct black patch, and dorsal surface with a dark") ("-shaped marking, but differs consistently in tibiotarsal articulation reaching anterior of eye (vs. tibiotarsal articulation reaching the tip of the snout in R. andersonii ), in flank near the crotch with a distinct black region between two creamy white patches (vs. a large black irregular spot on the groin extending halfway up the side with two yellow spots in R. andersonii ), and in ventral surface of the throat, chest, and belly opaque creamy white, with a lot of white spots (vs. chest and belly yellowish, but this color is nearly obscured by very fine brown punctuations in R. andersonii ); Raorchestes dulongensis sp. nov. shares with R. rezakhani the following morphological features: a similar body size, external single subgular vocal sac, nuptial pad absent, and outer metatarsal tubercle absent, but differs consistently in tympanum distinct (vs. tympanum indistinct in R. rezakhani ), in finger with lateral dermal fringes (vs. dermal fringe absent on finger in R. rezakhani ), in rudimentary webbing between toes (vs. webbing moderate, formula: I2-2+II1¾-2+III1½-3IV2¾-2̅V in R. rezakhani ), in head longer than wide (vs. head wider than long in R. rezakhani ), and in inner metatarsal tubercle present (vs. absent in R. rezakhani ).

Raorchestes dulongensis sp. nov. differs from other congeneric species distributed in eastern Himalayas and northeastern India. The new species is significantly different from R. manipurensis by SVL of adult male 15.0–19.0 mm (vs. 25.0 mm in R. manipurensis ), rudimentary webbing between toes (vs. toes almost 2/3 rd webbed in R. manipurensis ), webbing between fingers absent (vs. fingers moderate with rudiment of web in R. manipurensis ), head longer than wide (vs. head wider than long in R. manipurensis ), dorsal head brown (vs. head from snout to the beginning of eyes yellowish in R. manipurensis ), and flank brown, near the crotch with a distinct black region between two creamy white patches (vs. flanks yellowish with irregular brown patches in R. manipurensis ); from R. annandalii by relative toe lengths I <II <V <III <IV (vs. I <II <III <V <IV in R. annandalii ), rudimentary webbing between toes (vs. webbing present, medium in R. annandalii ), supernumerary tubercles in toes absent (vs. supernumerary tubercles in toes evident in R. annandalii ), and head longer than wide (vs. head wider than long in R. annandalii ); from R. sahai by SVL of adult male 15.0–19.0 mm (vs. 25.0–26.0 mm in R. sahai ), head longer than wide (vs. head wider than long in R. sahai ), snout obtusely pointed (vs. snout rounded in R. sahai ), iris golden brown (vs. eye blackish in R. sahai ), rudimentary webbing between toes (vs. toes nearly half-webbed in R. sahai ), a distinct “) (”-shaped dark marking on the back (vs. a dorsolateral white band on either side, extending from posterior region of eyes and ending posteriorly near the vent in R. sahai ), and the mid-dorsal line absent (vs. a dark narrow line originating from the inter-orbital region and extending posteriorly to the hindmost part of the body in R. sahai ); from R. shillongensis by head longer than wide (vs. head wider than long in R. shillongensis ), and inner metatarsal tubercle oval, outer metatarsal tubercle absent (vs. an indistinct inner metatarsal tubercle; outer metatarsal tubercle present in R. shillongensis ).

Raorchestes dulongensis sp. nov. differs from the remaining species of Clade A1 that is distributed in Western Ghats, India. The new species is significantly different from R. ghatei by relative finger length: I <II <IV <III (vs. relative finger length I <IV <II <III in R. ghatei ), narrow dermal fringe present on all toes (vs. absent in R. ghatei ), subarticular tubercles distinct, rounded, formula: 1, 1, 1, 2, 1 (vs. subartcular tubercles single in R. ghatei ), and finger discs and toe discs greyish or orange (vs. not orange in R. ghatei ); from R. tuberohumerus by the thigh having a similar black patch near the groin, proximal to another creamy white patch (vs. large yellow or reddish yellow markings near the groin in R. tuberohumerus ), relative finger length: I <II <IV <III (vs. relative finger length I <IV Ľ II <III in R. tuberohumerus ), and discs of fingers and toes orange (vs. grey to brown in R. tuberohumerus ); from R. leucolatus by relative toe lengths: I <II <V <III <IV (vs. relative toe length I <II <III <V <IV in R. leucolatus ), dorsal color brown, not having orange patch (vs. dorsum maroon with a pair of distinct orange patch on the shoulder in R. leucolatus ), tibiotarsal articulation reaching anterior of eye (vs. tibiotarsal articulation reaches posterior corner of eye in R. leucolatus ), and thigh having a black patch near the groin (vs. groin with distinct white blotches in R. leucolatus ); from R. bombayensis by nuptial pad absent (vs. distinct nuptial pad in R. bombayensis ), flank near the crotch with a distinct black region between two creamy white patches, and the thigh having a similar black patch near the groin, proximal to another creamy white patch (vs. groin and lateral side brown marbled with creamy white blotches in R. bombayensis ), and nostril closer to anterior corner of eyes than tip of snout (vs. nostril much nearer the tip of the snout than the eye in R. bombayensis ).

Raorchestes dulongensis sp.nov. is different from four species of the genus Philautus including P.namdaphaensis , P. kempiae , P. kempii , and P. garo . The four species occur in the Himalayas and northeastern India and their systematic status is still not clear. The new species is significantly different from P. namdaphaensis by head longer than wide (vs. head wider than long in P. namdaphaensis ), tympanum distinct (vs. indistinct in P. namdaphaensis ), rudimentary webbing between toes (vs. toes nearly half-webbed in P. namdaphaensis ), a distinct dark triangular marking between the eyes (vs. a broad white band in between the eyes in P. namdaphaensis ), mid-dorsal vertebral strip absent (vs. a thin mid dorsal line from snout to vent in P. namdaphaensis ), and a line along hindlimbs absent (vs. a thin line originating from vent and reaching up to heel through the thigh and tibia in P. namdaphaensis ); from P. kempiae by tympanum distinct (vs. hidden in P. kempiae ), tibiotarsal articulation reaching anterior of eye (vs. reaching the tip of the snout in P. kempiae ), canthus rostralis rounded, loreal region slightly concave (vs. canthus rostralis indistinct; loreal region oblique, feebly concave in P. kempiae ); and inner and outer metacarpal tubercles present (vs. absent in P. kempiae ); from P. kempii by supratympanic fold distinct (vs. absent in P. kempii ), inner and outer metacarpal tubercles present (vs. absent in P. kempii ), tibiotarsal articulation reaching anterior of eye (vs. reaching the tip of the snout in P. kempii ), inner metatarsal tubercle oval, outer metatarsal tubercle absent (vs. no metatarsal tubercles in P. kempii ), and ventral surface of the throat, chest, and belly brown, with many white spots (vs. ventral surface yellowish, suffused with dark olive; throat densely powdered with a similar shade but ornamented with clear yellowish spots in P. kempii ); from P. garo by head longer than wide (vs. head wider than long in P. garo ), dorsal of the head brown (vs. snout to front of eyes with a light yellowish patch in P. garo ), flank brown, near the crotch with a distinct black region between two creamy white patches (vs. flanks yellowish in P. garo ), and a distinct “) (”-shaped dark marking on the back (vs. a dark patch starting from behind the eye and above the tympanum continue mid dorsally towards the groin in P. garo ).

Figures

FIGURE 4. Male holotype (KIZ 035082) of Raorchestes dulongensis sp. nov. in life. Lateral (A), dorsal (B), ventral (C), the crotch (D), finger (E), and toe (F). Photos by Xiao-Long Liu.

FIGURE 5. Habitat at the type locality of Raorchestes dulongensis sp. nov. at Qinlangdang Village, Derung-Nu Autonomous County Gongshan, Yunnan Province, China. (Photos by Xiao-Long Liu)