Rhacophorus rhodopus—Hu 1987; Fei et al. 2004; Fei et al. 2009; Li et al. 2011; Fei et al. 2012; Li et al. 2022.

Rhacophorus bipunctatus—Che et al. 2020; Tang et al. 2024

SWU 0008699, adult male, collected in May 2024 by Xiaolong Liu, Renda Ai, and Xianqi Li from Didong Village, Medog, Xizang Tibetan Autonomous Region, China (29.2205°N, 95.1293°E, elevation 771 m; Fig. 2A).

Figure 2. 

(A) Large habitat at the type locality of R. medogensis sp. nov., Didong Village, Medog County, Xizang Tibetan Autonomous Region, China (29.2205°N, 95.1293°E, elevation 771 m); (B) macrohabitat of R. medogensis sp. nov. (SWU 0008601), Buqun (Xigong) Lake, Medog County, Xizang Tibetan Autonomous Region, China (29.25241°N, 95.225759°E, elevation 1361 m).

Six adult males (SWU 0008599, SWU 0008600, SWU 0008601, SWU 0008602, SWU 0008603, and SWU 0008604) were collected at Buqun (Xigong) Lake, Medog, Xizang Tibetan Autonomous Region, China (29.25241°N, 95.225759°E, elevation 1361 m). One subadult (SWU 0008701) was collected at the same locality as the holotype in May 2024 by Xiaolong Liu, Renda Ai, and Xianqi Li.

The specific epithet “medogensis” is named after the type locality, Medog, Xizang, China. We suggest “Xizang flying frog” as its English common name and “Mò Tuō Shù Wā” (墨脱树蛙) as its Chinese common name.

The genus Rhacophorus, also known as flying frogs, is characterized by the following features: 1) body size relatively moderate or large (SVL 30–100 mm, above 40 mm in most species); 2) presence of intercalary cartilage between terminal and penultimate phalanges of digits; 3) terminal phalanges of fingers and toes Y-shaped; 4) tips of the digits expanded into large disks bearing circummarginal grooves; 5) webbed fingers; 6) skin not co-ossified to the skull; 7) upper eyelid projections absent, tarsal projections present in most species; 8) dermal folds along the forearm or tarsus present; 9) pupil horizontal; 10) iris without “X”-shaped marking; 11) white foam nests or jelly-encapsulated eggs produced by breeding pairs; and (12) distributed mainly in Indochina (Jiang et al. 2019). Rhacophorus medogensis sp. nov. is placed in the genus Rhacophorus due to the combination of the following features: 1) body size relatively moderate (adult males SVL 31.6–38.7 mm, n = 17; adult females SVL 50.1–55.7 mm, n = 2); 2) presence of intercalary cartilage between terminal and penultimate phalanges of digits; 3) terminal phalanges of fingers and toes Y-shaped; 4) tips of the digits expanded into large disks bearing circummarginal grooves; 5) webbed fingers; 6) tarsal projections present; 7) pupil horizontal; 8) iris without “X”-shaped marking. Rhacophorus medogensis sp. nov. can be distinguished from other species in the R. rhodopus and R. bipunctatus complexes by the following combination of features: 1) medium adult males body size (adult males SVL 31.6–38.7 mm); 2) dorsal surface reddish brown, light green, light brown, or grayish green in life; 3) pineal ocellus obvious; 4) toe webbing formula: I1‒1II1‒1.5III1‒1IV1‒1V; 5) irregularly shaped large black spots, white pattern in black spots on flanks; 6) snout pointed with an appendage on the tip; 7) tongue pyriform, with a deep notch at the posterior tip; 8) throat rough; 9) palm rough with small tubercles; 10) tibiotarsal articulation reaching the eye.

Adult male, medium body size (SVL 33.5 mm); head length (HL 12.1 mm) longer than head width (HW 11.1 mm); snout pointed with an appendage on tip, sloping in profile, and protruding beyond the margin of lower jaw in ventral view; snout length (SL 5.0 mm) is longer than the diameter of the eye (ED 4.2 mm); the canthus rostralis is distinct and curved; loreal region oblique, concave; nostrils oval, lateral, slightly protuberant, and slightly closer to the tip of snout than the eye; the internarial space (IND 3.2 mm) is slightly smaller than the interorbital distance (IOD 4.6 mm) and larger than the width of the upper eyelid (UEW 2.5 mm); the pupil is horizontal; pineal ocellus obvious; tympanum distinct (TD 2.2 mm), rounded, and nearly about half of eye diameter (ED 4.2 mm); the supratympanic fold is narrow and flat; tongue pyriform, with a deep notch at the posterior tip; choanae oval; vomerine teeth present in two series; with an internal single subgular vocal sac; a vocal sac opening on the floor of the mouth at each corner (Fig. 3).

Figure 3. 

Holotype (SWU 0008699) of R. medogensis sp. nov. in preservative, showing (A) dorsal view, (B) ventral view, (C) Line drawing of the ventral view of hand, and (D) line drawing of the ventral view of foot. Scale bars: 10 mm.

Forelimbs strong, length of forearm and hand (FHL 16.3 mm); relative length of fingers I < II < IV < III; tips of all fingers expand into discs with circummarginal and transverse ventral grooves, disc of finger I smaller than discs of other fingers; entire web between fingers, webbing formula: I2‒2II1‒1.5III1‒1IV; subarticular tubercles rounded and prominent, formula 1, 3, 4, 4; inner metacarpal tubercle single, oval, and prominent (Fig. 3C).

Hindlimbs slender and long, heels overlapping when legs at a right angle to the body, tibiotarsal articulation reaching the eye; tibia length (TL 16.6 mm) nearly equal to the length of forearm and hand (FHL 16.3 mm), longer than foot length (FL 14.0 mm), and shorter than the length of tarsus and foot (TFL 22.4 mm); relative length of toes I < II < III < V < IV, with the third and fifth toes being nearly equal in length; tips of all toes expanded into discs with circummarginal and transverse ventral grooves; entire web between toes, webbing formula: I1‒1II1‒1.5III1‒1IV1‒1V; subarticular tubercles rounded and prominent, formula 1, 1, 2, 3, 2; supernumerary tubercles absent; single inner metatarsal tubercle, oval, outer metatarsal tubercle absent; tibiotarsal joint with a small triangular fold of skin (Fig. 3D).

Dorsal skin smooth with very fine granules; throat rough, covered with small warts, and ventral surface of forelimbs smooth; palm rough with small tubercles; chest, belly, and ventral surface of small warts (Fig. 3A, B); dermal folds on forearm, tarsus, heels, and vent present.

For coloration of the holotype in life (see Fig. 4). Dorsal surface reddish brown with a dark brown X-shaped marking; dark brown patches between the eyes; the dorsal surface of the body and limbs covered with small black dots; the supratympanic fold reddish brown; iris orange brown; the dorsal surface of limbs has distinct dark brown bands; a larger black spot present between the axillary and inguinal regions, as well as several smaller black spots located between the two larger spots, some white patterns in the black spots on flanks; ventral surface creamy white; throat pale yellow; ventral surface of the limbs orange; finger webbing yellow and toe webbing reddish orange; both the finger and toe discs are yellow.

Figure 4. 

Holotype (SWU 0008699) of R. medogensis sp. nov. in situ.

After preservation in alcohol, the color faded, but the general pattern did not change. Dorsal color changed to grey-brown with a dark X-shaped marking and some small black dots; the ventral surface faded to white; the white pattern in the large black spots on the flanks has disappeared (Fig. 3A, B).

Males are smaller than females (Che et al. 2020); the forearms are slightly more robust, with a milky-white nuptial pad on the inner side of the first finger base; they possess a single internal subgular vocal sac, with oval-shaped openings that are relatively large.

The coloration in living individuals is variable. The dorsal surface typically displays a reddish-brown coloration, characterized by irregular dark brown or chestnut spots. Some individuals present light green, light yellow, or light brown coloration. The dorsal coloration can change in response to variations in environmental colors and the individual’s condition. The black spots on the flanks exhibit three morphological forms: 1) a larger black spot typically present in the axillary and inguinal regions (SWU 0008602); 2) several smaller black spots located between the two larger spots (SWU 0008599, SWU 0008600, SWU 0008601, and SWU 0008699); 3) the presence of a single axillary spot without an inguinal spot (SWU 0008604 and SWU 0008701).

This species is currently known to be distributed only in Medog (Fig. 5). It inhabits humid shrublands, marshes, puddles, or slow-flowing ditches at elevations of 500–1700 m (Fig. 2B). Some individuals were found during the day in bamboo tubes with R. tuberculatus. Females are less common, and none were observed during surveys conducted in May.

Figure 5. 

Map showing the distribution pattern of R. rhodopus complex species in China. Distribution sites accessed from Tang et al. (2024) and our data, R. medogensis sp. nov., R. rhodopus and R. sp photoed by Xiaolong Liu, R. qiongica photoed by Chenxi Liao, R. napoensis and R. kio photoed by Junkai Huang.

Rather than comparing the new species to all known Rhacophorus, we focus on our morphological comparison with phylogenetically closely related taxa (R. rhodopus and R. bipunctatus complexes) (Table 6). Rhacophorus medogensis sp. nov. can be easily distinguished from R. helenae, R. kio, R. borneensis, R. norhayatiae, and R. reinwardtii by the dorsal surface being reddish brown (vs. green) and the web between toes being red with no black pigmentation (vs. black pigmentation present).

Rhacophorus medogensis sp. nov. differs from R. bipunctatus by 1) smaller body size (adult male SVL 31.6–38.7 mm, n = 17 vs. 37.8‒50.4 mm, n = 28; Table 6); 2) dorsal surface reddish brown, light green, light brown, or grayish green in life (vs. dorsal surface green in life); 3) dorsal surface reddish brown, light green, light brown, or grayish green in life (vs. dorsal surface green in life); 4) white pattern in black spots on flanks (vs. blue pattern in black spots on flanks); 5) snout pointed with appendage on tip (vs. snout pointed without appendage on tip); 6) distinct bands on limbs (vs. indistinct bands on limbs); 7) palm rough with small tubercles (vs. palm smooth without small tubercles); 8) tibiotarsal articulation reaching eye (vs. tibiotarsal articulation reaching beyond eye); 9) tongue pyriform (vs. tongue rounded); 10) pineal ocellus obvious (vs. pineal ocellus absent).

Rhacophorus medogensis sp. nov. differs from R. napoensis by 1) tibiotarsal articulation reaching eye (vs. tibiotarsal articulation reaching beyond eye); 2) tongue pyriform (vs. tongue cordiform); 3) pineal ocellus obvious (vs. pineal ocellus absent).

Rhacophorus medogensis sp. nov. differs from R. qiongica by 1) usually two large spots in the axillary and inguinal regions (vs. a series of small black spots on flanks); 2) white pattern in black spots on flanks (vs. no pattern in black spots on flanks); 3) snout pointed with appendage on tip (vs. snout pointed without appendage on tip); 4) throat rough (vs. throat smooth); 5) palm rough with small tubercles (vs. palm smooth without small tubercles); 6) tibiotarsal articulation reaching eye (vs. tibiotarsal articulation reaching beyond eye); 7) tongue pyriform (vs. tongue cordiform); 8) pineal ocellus obvious (vs. pineal ocellus absent); 9) toe webbing formula: I1‒1II1‒1.5III1‒1IV1‒1V (vs. toe webbing formula: I1‒1II1‒1III1‒1IV1‒1V).

Rhacophorus medogensis sp. nov. differs from its sister species R. rhodopus by 1) usually two large black spots in the axillary and inguinal regions (vs. one small black spot in the axillary region); 2) snout pointed with appendage on tip (vs. snout pointed without appendage on tip); 3) throat rough (vs. throat smooth); 4) tongue pyriform (vs. tongue narrow and long); 5) pineal ocellus obvious (vs. pineal ocellus absent).