Raorchestes yadongensis, Zhang & Shu & Shu & Li & Liu & Wu & Dong & Guo, 2022

Zhang, He, Shu, Guo-Cheng, Shu, Fu, Li, Ke, Liu, Qin, Wu, Ya-Yong, Dong, Bing-Jun & Guo, Peng, 2022, A new species of bush frog (Anura, Rhacophoridae, Raorchestes) from southern Xizang, China, Zootaxa 5195 (2), pp. 125-142 : 131-139

Raorchestes yadongensis sp. nov. Zhang, Shu, Liu, Dong & Guo

Figs. 3–5

Holotype. YBU 21223, adult male, collected from Xiayadong Town , Yadong County, Xizang Autonomous Region, China (27.43°N, 88.92°E; ca 2260 m a.s.l) on 24 th July 2021.

Paratypes. YBU 21222, YBU 21224, YBU 21225, three adult males, same data as the holotype .

Etymology. The specific epithet yadongensis refers to the type locality Yadong County, Xizang Autonomous Region, China. We suggest “Yadong Bush Frog” as its English common name and “Ya Dong Guan Shu Wa (亚东 灌mü)” as its Chinese common name.

Diagnosis. This new species can be distinguished from congeners of Raorchestes by its molecular phylogenetic position and the following morphological characters: (1) small body size, SVL 17.8–24.1 mm in adult males; (2) head wider than long; (3) eye diameter about three times as much as tympanum diameter; (4) tympanum distinct; (5) fingers with rudimentary webbing and narrow lateral dermal fringes; relative finger lengths I <II <IV <III; number of subarticular tubercles in fingers 1, 1, 2, 1; (6) toes with rudimentary webbing and narrow lateral dermal fringes; relative toe lengths I <II <III <V <IV; number of subarticular tubercles in toes 1, 1, 2, 3, 2; inner metatarsal tubercle distinct, outer metatarsal tubercle absent; (7) tips of fingers and toes present discs, and discs pale brown or yellow in life; (8) tibiotarsal articulation reaching the tip of snout when adpressed; (9) milky nuptial pad present on the dorsal surface of first finger; (10) dorsal surface light brown with white warts, ventral surface with irregular white patches.

Description of holotype. YBU 21223, adult male. Small sized body, SVL 24.1 (all measurements in mm); flat dorsally; upper jaw protruding slightly in ventral view; head wider than long (HDW = 13.4; HDL = 6.9); internarial distance (IND = 3.1) longer than snout–nostril length (NS = 1.3), eye–nostril distance (EN = 2.0) larger than snout–nostril length; canthus rostralis slightly round, loreal region clearly concave; nostril closer to anterior corner of eyes than tip of snout (SL = 3.9); interorbital region flat and larger (IOD = 5.0) than upper eyelid width (UEW = 3.1); several tubercles on upper eyelid; tympanum distinct, smaller (TD = 1.3) than head width, equal to snout length, edge of tympanum raised; eyes relatively large, pupil round, eye diameter three times that of tympanum (ED = 3.9); vomerine teeth absent; tongue notched; single translucent external subgular vocal sac present; pupil oval, horizontal.

Forelimb relatively long (FL = 12.5). Relative finger lengths I <II <IV <III (F1L = 1.5; F2L = 2.1; F3L = 3.7; F4L = 2.3); tip of fingers with well-developed discs (F1DW = 0.5; F2DW = 0.7; F3DW = 1.0; F4DW = 0.9), with horseshoe-shaped horizontal groove; fingers with rudimentary webbing and with narrow lateral dermal fringes; subarticular tubercles distinct, rounded, number of subarticular tubercles on fingers 1, 1, 2, 1; supernumerary tubercles absent; nuptial pad present on the dorsal surface of first finger.

Hindlimb long (HL = 36.6), tibia length obviously larger than foot length (TL = 13.3; FOL = 11.2); tibiotarsal articulation reaching the tip of snout when adpressed; heels distinctly overlapped when thighs held at right angles to body. Relative toe lengths I <II <III <V <IV (T1L = 1.6; T2L = 2.1, T3L = 3.8; T4L = 6.0; T5L = 3.9); tips of all toes expanded into well-developed discs (T1DW = 0.6; T2DW = 0.8; T2DW = 0.9; T4DW = 1.0, T5DW = 0.9), with circum-marginal grooves; toes with rudimentary webbing and narrow dermal fringe; subarticular tubercles distinct, rounded, number of subarticular tubercles on toes 1, 1, 2, 3, 2; supernumerary tubercles absent; inner metatarsal tubercles distinct and oval, outer metatarsal tubercles absent.

Dorsal surface with tubercles scattered on head towards vent. Dorsal body and limbs covered with small warts. Supratympanic fold weakly distinct, extending from posterior corner of eye to end of tympanum. Distinct tubercles scattered along temporal region and flanks. Ventral surface smooth.

Coloration of holotype: In life, dorsal and lateral body light brown, with distinct dark triangular marking between eyes; tibia darker than dorsal body, with light black band; small warts on dorsal surface and limbs white. Dorsal discs of fingers and toes pale brown or yellow, nuptial milky. Ventral head and body white, with irregular white spots near arm; ventral limbs gray ( Fig. 3 ).

In preservative, dorsal body gray and yellow, warts distinct; ventral surface pale with white patch ( Fig. 4 ).

TABLE 3. (Continued)

Variation. Females are unavailable and sexual dimorphism could not be determined. Morphometric variation of the four male individuals were provided in Table 4 . All specimens were very similar, except for body size.

Distribution and ecology. Raorchestes yadongensis sp. nov. is only known from the type locality in Yadong County, Xizang, China, but may also occur in neighboring Bhutan and India. All specimens were found in shrubs and herbs on either side of the road at elevations of ca 2000 m a.s.l., during rainy nights in July ( Fig. 6 ). Males called vibrantly at night, but none were heard calling during the day. They were common at rainy night in July, but were not found at the end of August and no calling was heard.

Comparisons. Raorchestes yadongensis sp. nov. is here compared with the 14 known congeners distributed in southwestern China, Indochina, Himalayas, and northeastern India as mentioned in the Introduction, due to their close phylogenetic relationship ( Fig. 2 ) and distributions. We further present a detailed morphological comparison with species from China ( Table 5 ).

Raorchestes yadongensis sp. nov. differs from R. hillisi by its larger body size, SVL 17.8–24.1 mm in males (vs SVL 15.9–17.7 mm in males), dorsal surface with white warts (vs dorsal surface without white warts), head wider than long (vs head longer than wide), fingers and toes with narrow lateral dermal fringes (vs fingers and toes lacking lateral dermal fringe), fingers with rudimentary webbing (vs absent), tibiotarsal articulation reaching the tip of snout when adpressed (vs tibiotarsal articulation reaching the eye when adpressed), and ventral surface smooth without tubercles (vs ventral surface covered with relatively large flat tubercles).

The new species is distinct from R. dulongensis by head wider than long (vs head longer than wide), fingers with rudimentary webbing (vs absent), nuptial pad present (vs absent), relative toe lengths I <II <III <V <IV (vs I <II <V <III <IV), and tibiotarsal articulation reaching the tip of snout when adpressed (vs tibiotarsal articulation reaching anterior of the eye when adpressed).

Raorchestes yadongensis sp. nov. can be distinguished from R. longchuanensis by head wider than long (vs head length almost equal to width), toes with narrow lateral dermal fringes (vs absent), fingers with rudimentary webbing (vs absent), toes with rudimentary webbing (vs toes with one-fourth webbing), tibiotarsal articulation reaching the tip of snout when adpressed (vs tibiotarsal articulation reaching the eye when adpressed), and ventral surface smooth without warts (vs ventral surface with dense warts).

The new species can be distinguished from R. cangyuanensis by tympanum distinct (vs indistinct), relative toe lengths: I <II <III <V <IV (vs I <II <V <III <IV), tibiotarsal articulation reaching the tip of snout when adpressed (vs tibiotarsal articulation reaching anterior of the eye when adpressed), and fingers with rudimentary webbing (vs absent).

The new species can be differentiated from R. huanglianshan by head longer than wide (vs head slightly wider than length or equal), fingers with rudimentary webbing (vs absent), fingers and toes with narrow lateral dermal fringes (vs fingers and toes lacking lateral dermal fringe), and tibiotarsal articulation reaching the tip of snout when adpressed (vs tibiotarsal articulation reaching the eye when adpressed).

Raorchestes yadongensis sp. nov. differs from R. menglaensis by larger body size, SVL 17.8–24.1 mm in males (vs SVL 15.0–18.0 mm in males), head longer than wide (vs head length almost equal to width), tympanum distinct (vs indistinct), fingers with rudimentary webbing (vs absent), outer metatarsal tubercles absent (vs outer metatarsal tubercles distinct), tibiotarsal articulation reaching the tip of snout when adpressed (vs tibiotarsal articulation reaching the eye when adpressed), and ventral surface smooth without tubercles (vs ventral surface covered with relatively large flat tubercles).

The new species can be differentiated from R. andersoni by relative smaller eye diameter, about three times as much as tympanum diameter (vs eye diameter four times as much as tympanum diameter), and fingers with rudimentary webbing (vs absent).

The new species differs from R. gryllus by smaller body size, SVL 17.8–24.1 mm in males (vs 25.0–27.0 mm in males), tympanum distinct (vs indistinct), toes with rudimentary webbing (vs little more than half webbing in toes), and outer metatarsal tubercles absent (vs outer metatarsal tubercles distinct).

Raorchestes yadongensis sp. nov. differs from R. parvulus by tympanum distinct (vs indistinct), nuptial pad present (vs absent), fingers with rudimentary webbing (vs absent), toes with rudimentary webbing (vs toes with medium webbing), and tibiotarsal articulation reaching the tip of snout when adpressed (vs tibiotarsal articulation reaching the posterior corner of the eye when adpressed).

The news species differs from R. rezakhani by tympanum distinct (vs indistinct), nuptial pad present (vs absent), fingers with narrow lateral dermal fringes (vs absent), fingers with rudimentary webbing (vs absent), toes with rudimentary webbing (vs toes webbing moderate), relative toe lengths I <II <III <V <IV (vs I <II <V <III <IV), and inner metatarsal tubercles distinct (vs inner metatarsal tubercles absent).

The new species differs from R. annandalii by larger body size, SVL 17.8–24.1 mm in males (vs 16.0 mm in males), inner metatarsal tubercles distinct (vs inner metatarsal tubercles absent), fingers with rudimentary webbing (vs absent), and tibiotarsal articulation reaching the tip of snout when adpressed (vs tibiotarsal articulation reaching the posterior corner of the eye when adpressed).

Raorchestes yadongensis sp. nov. can be differentiated from R. shillongensis by larger body size, SVL 17.8– 24.1 mm in males (vs 10.0–20.0 mm in males), and fingers with rudimentary webbing (vs absent).

The new species is differentiated from R. sahai by smaller body size, SVL 17.8–24.1 mm in males (vs 25.0– 26.0 mm in males), fingers with rudimentary webbing (vs absent), and toes with rudimentary webbing (vs. toes with nearly half webbing).

The new species can be differentiated from R. manipurensis by smaller body size, SVL 17.8–24.1 mm in males (vs 25.0 mm in males), and toes with rudimentary webbing (vs toes with two-thirds webbing).

Figures

FIGURE 2. Phylogeny of Raorchestes based on mitochondrial 16S rRNA and ND1 genes. Nodal support values with Bayesian posterior probability (BPP) and ML inferences bootstrap support (BS) are shown near respective nodes. Symbol “-” denotes BPP <90% or BS <70.

FIGURE 3. Lateral (A), dorsal (B), and ventral (C) views of holotype of Raorchestes dulongensis sp. nov. (YBU 21223) in life.

FIGURE 4. Holotype of Raorchestes yadongensis sp. nov. (YBU 21223) showing dorsal (A) and ventral (B) views of body; ventral view of hand (C); ventral view of foot (D).

FIGURE 5. Paratype of Raorchestes yadongensis sp. nov. (YBU 21222) showing dorsal (A) and ventral (B) views of body; hand (C) and foot (D).

FIGURE 6. Macrohabitat (A) and microhabitat (B) of Raorchestes yadongensis sp. nov. from type locality in Yadong County, Xizang, China.