Leptobrachella weixinensis, Liu & Chen & Xu & Wu, 2025

Liu, Nai-Yi, Chen, Lu, Xu, Wei & Wu, Yun-He, 2025, Morphological and molecular evidence reveal a new Asian leaf litter toad of the genus Leptobrachella Smith, 1925 (Anura, Megophryidae) from the northeastern hills of Yunnan, China, Zoosystematics and Evolution 101 (4), pp. 1397-1408 : 1397-1408

Leptobrachella weixinensis sp. nov.

Figs 3 , 4 , Table 1

Holotype.

• NNU 040615 , an adult male collected from Shizigou village , Zhaxi Town, Weixin County, Zhaotong, Yunnan Province, China (27.84730 ° N, 105.02633 ° E; elevation 1280 m a. s. l.), collected by Lu Chen on 15 June 2024.

Paratypes.

• Two males, NNU 040602 and NNU 040603 , collected at the same locality and with same collection information as the holotype .

Etymology.

The specific epithet “ weixinensis ” is given as a noun in apposition and refers to the name of the Weixin County in Yunnan Province, China, where the new species occurs. We suggest the English common name “ Weixin Leaf Litter Toad ” and the Chinese common name “ 威信掌突蟾 ” (Wēi Xìn Zhǎng Tū Chán).

Diagnosis.

Leptobrachella weixinensis sp. nov. is assigned to the genus Leptobrachella morphologically by the presence of small size, presence of macroglands (supra-axillary, femoral, and ventrolateral glands), vomerine teeth absent, rounded finger tips, and presence of an elevated inner metacarpal tubercle not continuous to the thumb (e. g., Dubois 1980; Ohler et al. 2011; Rowley et al. 2013). The new species can be further distinguished from its congeners by the combination of: (1) small body size (SVL 28.2–29.7 mm in three males); (2) interorbital space wider than internarial distance; (3) upper margin of tympanum incontact with supratympanic ridge; (4) tibiotarsal articulation reaches the nostril when hindlimb is stretched along the side of the body; (5) heels overlapping; (6) toes with rudimentary webbing and narrow lateral fringes; (7) flanks with large irregular black spots; (8) iris distinctly bicolored, typically orange in upper half, silver white in lower half; (9) ventral surface of throat, chest, and belly creamy white; chest and abdomen with distinct dark patches; (10) supratympanic ridge distinct with reddish-brown pigmentation.

Description of holotype

(Table 1 ). NNU 040615 , sexually mature male, body size small, SVL 28.2 mm; head length (HDL 10.0 mm) almost equal to head width (HDW 10.1 mm); head triangular in dorsal view; snout short (SNT / HDL 38.0 %), snout round in both dorsal view and profile, projecting beyond margin of lower jaw (Fig. 3 A, B ); oval-shaped nostril closer to tip of snout than to anterior margin of eye; canthus rostralis indistinct; loreal region slightly concave; eyes large (ED / HDL 36.0 %), protuberant in both dorsal and lateral views; eye diameter twice of the maximum tympanum diameter (TD / ED 200 %) and subequal to snout length (ED / SNT 94.7 %); tympanum distinct, rounded, tympanic ring slightly elevated relative to skin of temporal region (Fig. 3 ); upper margin of tympanum incontact with supratympanic ridge; eye-tympanum distance less than twice as long as maximum tympanum diameter (TED / TD 55.6 %); pupil vertical; interorbital space (IOD 3.3 mm) flat, wider than internarial distance (INS 2.4 mm) and width of upper eyelid (UEW 2.8 mm); vomerine teeth absent; tongue with shallow notch at posterior tip; vocal sac openings slit-like, paired, located posterolaterally on floor of mouth; supratympanic ridge distinct with reddish-brown pigmentation, extending from posterior corner of eye to supra-axillary gland, the posterior end of supratympanic ridge not expanded (Fig. 3 ).

Forelimb relatively long, forearm shorter than hand, not enlarged (FAL 7.3 mm, HL 7.6 mm); fingers slender, relative finger lengths: I = IV <II <III; tips of fingers rounded, slightly swollen; subarticular tubercles absent on fingers; supernumerary tubercles absent; webbing between fingers absent; inner metacarpal tubercle large and rounded, separated from the smaller, round outer metacarpal (Fig. 3 E ).

Hindlimbs relatively long; thigh length greater than tibia length (TL / THL 92.4 %) and foot length (FL / THL 95.8 %); tibiotarsal articulation reaches the nostril when hindlimb is stretched along the side of the body; heels overlapping when thighs are positioned at right angles to the body; relative toe lengths: I <II <V <III <IV; tips of toes rounded, slightly swollen; subarticular tubercles distinct under the base of I, II, III, and IV toes; rudimentary webbing between toes; narrow lateral fringes present on all toes; inner metatarsal tubercle elongated (IMTL 1.4 mm, 5.0 % SVL), outer metatarsal tubercle absent (Fig. 3 F ).

Dorsal skin relatively smooth; tiny white tubercles scattered on flanks; oval supra-axillary gland raised, located in axillary region dorsally from insertion of forelimb, approximately 0.8 mm in diameter; ventral skin smooth; pectoral gland laterally compressed, 1.0 mm in diameter; oval femoral glands distinct on posteroventral surface of thigh, approximately 0.9 mm in diameter, located on posteroventral surfaces of thighs, closer to knee than to vent; ventrolateral glands, distinctly visible, raised, forming an incomplete line (Fig. 3 ).

Color of the holotype in life.

Dorsal surface of body brown, with distinct, black, inverted triangular pattern between the anterior corners of the eyes in connection with a dark brown W-shaped marking in the interorbital region, which is also connected to a W-shaped marking between the axillae; wide dark brown bars in upper lip, with distinct white spots; canthus rostralis reddish; flanks with large irregular black flecks and several small light tangerine tubercles; supratympanic ridge reddish and a large black marking under supratympanic ridge; tympanum bicolored, with the upper 2 / 3 of the tympanum dark brown and the lower 1 / 3 light brown; elbow to upper arm and tibio-tarsal articulation distinctly coppery orange in color on the dorsum; transverse black bars on dorsal surfaces of fingers and toes, lower arms, tarsus, thighs and tibia; iris distinctly bicolored, typically orange in upper half, silver white in lower half, with black reticulations throughout; ventral surface of throat, chest, and belly creamy white; chest and abdomen with distinct dark patches; ventral surface of head and limbs greyish purple; ventral surface of limbs scattered with creamy white spots and small patches; pectoral and femoral glands creamy white, supra-axillary glands light orange (Fig. 3 and Suppl. material 4).

Color of holotype in preservative.

After three months of storage in 70 % alcohol, the dorsum and limb surfaces fading to uniform light brown, except for upper arm; upper arm surface copper brown; transverse bars on limbs still distinct; ventral surface of limbs, chest, abdomen, and throat greyish white; pectoral, femoral, supra-axillary, and ventrolateral glands greyish white; subarticular tubercles, metacarpal tubercles, and metatarsal tubercle fading to gray (Fig. 4 ).

Distribution and ecology.

At present, this species is known to be distributed only in its type locality, that is, the mountains around Shizigou Village, Zhaxi Town, Weixin County, with an altitude of 1280–1400 meters. During the breeding season, it gathers in mountain streams with a width of 1.5–2 meters, surrounded by typical subtropical evergreen broad-leaved forests and bamboo forests (Fig. 5 ). The stream has a steep slope and low water temperature. There are often waterfalls and pools. The banks are covered with lush plants, mainly grasses. The village can be seen about 1 km away from the stream. Species that inhabit the same environment include Nanorana yunnanensis and Bufo andrewsi .

During a field survey in mid-June, male toads were heard chirping in the cracks of huge rocks or under grass leaves beside streams. The chirping sound was like a cricket and varied. When not disturbed, the chirping sound consisted of two syllables, with an interval of about 0.5 seconds between each segment. When stimulated by light or someone passing by, the chirping sound changed to a long single syllable. After the environment stabilized, the chirping sound gradually returned to its former state. If further stimulated, such as by direct light, the toad stopped chirping, shrank into the cracks of the rocks, or crouched until it felt that the surrounding environment was safe. However, no tadpoles were observed during this period, nor were female toads.

Comparisons.

Phylogenetically, the matrilineal genealogy assigns Leptobrachella weixinensis sp. nov. to L. oshanensis complex (clade A). Thus, we compared Leptobrachella weixinensis sp. nov. to all other recognized species of L. oshanensis complex from clade A, which include L. bijie , L. jinyunensis , L. chishuiensis , L. suiyangensis , L. jinshaensis , L. purpuraventra , L. bourreti , L. dong , L. dushanensis , L. graminicola , L. yeae , L. wulingensis , L. dorsospina , L. yunyangensis , L. niveimontis , L. alpina , L. purpurus , L. eos , L. oshanensis , L. murphyi , L. korifi , L. sinorensis , and L. tengchongensis (e. g., Ohler et al. 2011; Yang et al. 2016, 2018; Wang et al. 2019, 2020; Chen et al. 2020, 2021; Li et al. 2020, 2024; Luo et al. 2020; Cheng et al. 2021; Nguyen et al. 2021; Shi et al. 2021; Luo et al. 2022; Chen et al. 2023; Liu et al. 2023; Matsui et al. 2023; Shi et al. 2023; Suppl. material 3).

Leptobrachella weixinensis sp. nov. is significantly different from L. jinyunensis by tibiotarsal articulation reaches the nostril (vs. reaches the level of the middle of the eye), subarticular tubercles distinct under the base of I, II, III and IV toe (vs. absent), dorsal skin relatively smooth (vs. dorsal skin rough with large tubercles in size of humeral glands, without conical spines), iris distinctly bicolored, typically orange in upper half, silver white in lower half (vs. iris gold above, gradually silver bellow), and heels overlapping when thighs are positioned at right angles to the body (vs. heels slightly contact with each other); from L. bijie by interorbital distance wider than internarial distance (vs. internarial distance equal to interorbital distance), tibiotarsal articulation reaches the nostril (vs. reaches the region between middle of eye to anterior corner of eye), heels overlapping when thighs are positioned at right angles to the body (vs. heels just meeting), and flanks with large irregular black flecks (vs. flanks with several dark blotches, longitudinally in two rows); from L. chishuiensis by interorbital distance wider than internarial distance (vs. interorbital distance shorter than internasal distance), tibiotarsal articulation reaches the nostril (vs. reaches the tympanum), upper margin of tympanum incontact with supratympanic ridge (vs. upper margin of tympanum in contact with supratympanic ridge), and relative finger lengths: I ≈ IV <II <III (vs. relative finger lengths: II <IV <I <III); from L. suiyangensis by tibiotarsal articulation reaches the nostril (vs. reaches to the anterior eye), heels overlapping when thighs are positioned at right angles to the body (vs. heels meeting each other), subarticular tubercles distinct under the base of I, II, III and IV toe (vs. absent), dorsal skin relatively smooth (vs. dorsal skin is shagreened and scattered with fine and rounded granules), and relative finger lengths: I ≈ IV <II <III (vs. relative finger lengths: I <II <IV <III); from L. jinshaensis by tibiotarsal articulation reaches the nostril (vs. tibiotarsal articulation reaches middle eye), rudimentary webbing between toes (vs. toes without webbing), upper margin of tympanum incontact with supratympanic ridge (vs. upper margin of tympanum in contact with supratympanic ridge), dorsal skin relatively smooth (vs. dorsal skin shagreened, some of the granules forming longitudinal short skin ridges), and subarticular tubercles distinct under the base of I, II, III and IV toe (vs. absent); from L. purpuraventra by tibiotarsal articulation reaches the nostril (vs. reaches the middle of eye), dorsal skin relatively smooth (vs. dorsal skin shagreened, some of the granules forming longitudinal short skin ridges), ventral surface of throat, chest, and belly creamy white, chest and abdomen with distinct dark patches (vs. ventral surface grey purple, with distinct or indistinct nebulous greyish speckling on chest and ventrolateral flanks), and subarticular tubercles distinct under the base of I, II, III and IV toe (vs. absent); from L. dong by narrow lateral fringes present on all toes (vs. toes with wide lateral fringes), tibiotarsal articulation reaches the nostril (vs. reaches the middle of eye), upper margin of tympanum incontact with supratympanic ridge (vs. upper margin of tympanum in contact with supratympanic ridge), and relative finger lengths: I ≈ IV <II <III (vs. relative finger lengths: II <I <IV <III); from L. dushanensis by narrow lateral fringes present on all toes (vs. wide lateral fringes present on all toes), upper margin of tympanum incontact with supratympanic ridge (vs. upper margin of tympanum in contact with supratympanic ridge), relative finger lengths: I ≈ IV <II <III; (vs. relative finger lengths: II <I <IV <III), and tibiotarsal articulation reaches the nostril (vs. reaches interior corner of the eye); from L. graminicola by SVL 28.2–29.7 mm in three males (vs. 23.1–24.6 mm in six adult males), narrow lateral fringes present on all toes (vs. toes with broad lateral fringes), subarticular tubercles distinct under the base of I, II, III and IV toe (vs. absent), and ventral surface of throat creamy white without spot (vs. throat dark brown with light grey-brown flecks and spots); from L. yeae by relative finger lengths: I ≈ IV <II <III (vs. relative finger lengths: II <I <IV <III), tibiotarsal articulation reaches the nostril (vs. reaches the middle eye), pectoral gland distinct (vs. indistinct), and subarticular tubercles distinct under the base of I, II, III and IV toe (vs. absent); from L. wumingensis by tongue with shallow notch at posterior tip (vs. tongue with a deep notch at posterior tip), toes with rudimentary webbing and narrow lateral fringes (vs. absence of toe webbing and lateral fringes), subarticular tubercles distinct under the base of I, II, III and IV toe (vs. absent), tibiotarsal articulation reaches the nostril (vs. reaches the middle eye), and heels overlapping (vs. heels meeting); from L. dorsospina by relative finger lengths: I ≈ IV <II <III (vs. relative finger lengths: II = IV <I <III), dorsal skin relatively smooth (vs. dorsal skin rough, with dense conical granules, tubercles, glandular folds and conical spines), tibiotarsal articulation reaches the nostril (vs. reaches the posterior corners of eyes), and black spots on irregular on flanks (vs. black spots on flanks in two rows); from L. yunyangensis by tibiotarsal articulation reaches the nostril (vs. reaches to the anterior corner of the eye), relative finger lengths: I ≈ IV <II <III (vs. relative finger lengths: I <II = IV <III), upper margin of tympanum incontact with supratympanic ridge (vs. upper margin of tympanum in contact with supratympanic ridge), tongue with shallow notch at posterior tip (vs. tongue cordiform, deeply notched behind), and dorsal skin relatively smooth (vs. dorsal skin rough, with sparse large granules and tubercles and short longitudinal ridges on the shoulder); from L. niveimontis by SVL 28.2–29.7 mm in three males (vs. 22.5–23.6 mm in four adult males), heels overlapping (vs. heels meeting), and throat, chest, and belly creamy white, chest and abdomen with distinct dark patches (vs. black and bluish-white marbling all over ventral surfaces of throat, chest and belly, denser on throat than on chest and belly); from L. purpurus by narrow lateral fringes present on all toes (vs. toes with wide lateral fringes), dorsal surface of body brown (vs. dorsum coloration purplish brown in life), iris bicolored, typically orange in upper half, silver white in lower half (vs. iris bicolored, upper half orange yellow, lower half sliver white), and tibiotarsal articulation reaches the nostril (vs. reaches to posterior corner of the eye); from L. alpina by narrow lateral fringes present on all toes in males (vs. toes with wide lateral fringes in males), tibiotarsal articulation reaches the nostril (vs. reaches to anterior corner of the eye), and head longer than wide (vs. approximately equal); from L. oshanensis by narrow lateral fringes present on all toes (vs. toes without lateral fringes), subarticular tubercles distinct under the base of I, II, III and IV toe (vs. absent), tongue with shallow notch at posterior tip (vs. tongue with a deep notch at posterior tip), interorbital distance wider than internarial distance (vs. interorbital distance distance equal to internarial), and pectoral glands distinct (vs. invisible); from L. eos by a smaller body size, SVL 28.2–29.7 mm in three males (vs. 33.1–34.7 mm in six adult males), supratympanic fold prominent (vs. absent), narrow lateral fringes present on all toes (vs. toes with wide lateral fringes), flanks with large irregular black spots (vs. absent), and iris bicolored, typically orange in upper half, silver white in lower half (vs. iris orange above, light golden below); from L. bourreti by nostril closer to tip of snout than to anterior margin of eye (vs. nostrils closer to eye than to tip of snout), femoral and ventrolateral glands distinct (vs. femoral glands and ventrolateral gland indistinct), vocal sac openings slit-like, paired, located posterolaterally on floor of mouth (vs. no opening on mouth floor), and interorbital distance wider than internarial distance (vs. internarial distance equal to interorbital distance); from L. murphyi by SVL 28.2–29.7 mm in three males (vs. 23.2–24.9 mm in ten adult males), narrow lateral fringes present on all toes (vs. wide lateral fringes present on all toes), heels overlapping (vs. heels meeting), and dorsal skin relatively smooth (vs. dorsal skin relatively rough with small tubercles and short folds with reddish tips); from L. korifi by tibiotarsal articulation reaches the nostril (vs. reaches anterior corner of eye), and interorbital distance slightly wider than internarial distance (vs. internarial distance equal to interorbital distance); from L. sinorensis by tibiotarsal articulation reaches the nostril (vs. reaches center of eye), and dorsal surface of body brown, without pink dots (vs. light brown dorsally on head and body, with dark spots, partly dotted with pink); from L. tengchongensis by SVL 28.2–29.7 mm in three males (vs. 23.9–26.0 mm in five adult males), ventrolateral glands distinct (vs. ventrolateral glands indistinct), dorsal skin relatively smooth (vs. skin on dorsum shagreened and scattered with fine, round tubercles), and iris distinctly bicolored, typically orange in upper half, silver white in lower half, with black reticulations throughout (vs. iris not bicolored, uniformly dark brown and scattered with minute, coppery reticulations throughout).

Figures

Figure 3. Holotype of Leptobrachella weixinensis sp. nov. (NNU 040615) in life. A. Lateral view; B. Lateral view of head; C. Dorsal view; D. Ventral view; E. Thenar view of the right hand, and F. Plantar view of the right foot. Photos by Yun-He Wu.

Figure 4. Holotype of Leptobrachella weixinensis sp. nov. (NNU 040615) in preservative. A. Dorsal view; B. Ventral view; C. Thenar view of the right hand; D. Plantar view of the right foot. Photos by Yun-He Wu.

Figure 5. Habitat at the type locality of Leptobrachella weixinensis sp. nov. at Shizigou village, Weixin County, Yunnan Province, China. (Photo by Lu Chen)