Leptobrachella yachangensis, Huang & Zeng & Wang & Wang & Deng & Wang & Liao & Mo, 2025

Huang, Zhong, Zeng, Zhao-Chi, Wang, Jian, Wang, Hao-Tian, Deng, Zhen-Hai, Wang, Zhi-Wei, Liao, Xiao-Wen & Mo, Yun-Ming, 2025, A new species of the genus Leptobrachella Smith, 1935 (Anura, Megophryidae) from northwestern Guangxi, China, Herpetozoa 38, pp. 321-332 : 321-332

Leptobrachella yachangensis sp. nov.

Fig. 3 Yachang Leaf Litter Toad (in English) / Ya Chang Zhang Tu Chan (雅长掌突蟾 in Chinese )

Type materials.

Holotype ♂. NHMG 250402 , collected by Yun-Ming Mo and Zhong Huang on 15 April 2025 from Guangxi Yachang Orchid National Nature Reserve ( 24°44'57.24"N, 106°19'38.94"E; ca. 1400 m a. s. l.), Leye County, Baise City, Guangxi, China.

Paratypes. 6 ♂: NHMG 250401 , NHMG 250409 -250414, the same collection data as the holotype ; NHMG 250401 , collected by Yun-Ming Mo and Zhong Huang on 15 April 2025 from Guangxi Yachang Orchid National Nature Reserve ( 24°45'6.85"N, 106°19'22.38"E; ca. 1250 m a. s. l.) ; NHMG 250409 -250414, collected by Yun-Ming Mo and Zhong Huang on 16 April 2025 from Guangxi Yachang Orchid National Nature Reserve ( 24°44'52.82"N, 106°20'2.06"E; ca. 1610 m a. s. l.) .

Etymology.

The specific epithet, yachangensis , is in reference to the type locality, Yachang Orchids National Nature Reserve.

Diagnosis.

(1) Small body size [ SVL 28.1–31.2 mm in seven adult males], (2) iris bicolored, upper half coppery orange and lower half grayish brown, (3) tympanum distinct, (4) supratympanic line black, (5) fingers without lateral fringes, (6) toes with narrow lateral fringes, lacking webbing, (7) longitudinal ridges under toes continuous, (8) heels overlapping when adpressed, tibial-tarsal articulation reaching anterior corner of eye, (9) dorsal surface rough with dense skin ridges and numerous conical tubercles bearing spines, (10) ventral surface smooth, with transparent tiny conical spines on chest and abdomen in breeding males, (11) dorsum grayish brown, with darker brown scattered markings, (12) flanks with several dark spots, (13) surface of throat, chest and abdomen creamy white, with dense irregular dark brown speckles.

Description of holotype.

Adult male. Body size small, SVL 31.2 mm. Head length slightly larger than head width, HDW / HDL 0.90; snout slightly protruding, projecting slightly beyond margin of lower jaw; nostril closer to snout than eye; canthus rostralis gently rounded; loreal region slightly concave; interorbital space flat, internarial distance slightly larger than interorbital distance, IND / IOD 1.07; pineal ocellus absent; pupil vertical; snout slightly longer than eye diameter, SNT / EYE 1.07; tympanum distinct, rounded, diameter smaller than that of eye and larger than tympanum-eye distance, TMP / EYE 0.48, TEY / TMP 0.48; upper margin of tympanum in contact with supratympanic ridge; vomerine teeth absent; a single vocal sac; vocal sac openings slit-like, paired, located posterolaterally on floor of mouth, close to margins of mandible; tongue deeply notched distally; supratympanic ridge distinct, extending from posterior corner of eye to supra-axillary gland.

Tips of fingers rounded, slightly swollen; relative finger lengths I <II <IV <III; nuptial pad absent; subarticular tubercles absent; inner palmar tubercle large, rounded, distinctly separated from outer palmar tubercle; outer palmar tubercle small, rounded; fingers lacking interdigital webbing and lateral fringes. Tips of toes rounded, slightly swollen; relative toe length I <II <V <III <IV; longitudinal ridges under toes continuous; inner metatarsal tubercle large, oval; outer metatarsal tubercle absent; interdigital webbing between toes absent; narrow lateral fringes present on all toes. Tibia 47 % of snout-vent length; tibiotarsal articulation reaches to anterior corner of eye; heels overlapping when thighs are appressed at right angles with respect to body.

Dorsal surface rough with dense skin ridges and numerous conical tubercles bearingspines; ventral skin smooth with transparent tiny conical spines on chest and abdomen; pectoral and femoral glands oval, both larger in diameter than tip of fingers; femoral glands larger in diameter than tip of toes; femoral gland situated on posteroventral surface of thigh, closer to knee than to vent; supra-axillary gland raised. Ventrolateral gland distinctly visible, forming a longitudinal uncontinuous series.

Coloration of holotype in life.

Dorsal background color grayish brown, with darker brown markings. A dark brown inverted triangular marking in interorbital region, connecting to dark brown W-shaped marking on occipital region. Tympanum grayish brown. Supratympanic line black. Transverse dark brown bars on dorsal surfaces of distal limbs and digits; distinct dark brown spots on flanks; surfaces of digits, elbows, upper arms and tibiotarsal articulations coppery orange, with dark markings and spots.

Surface of throat, chest and abdomen creamy white, with dense irregular dark brown speckles. Underside of limbsgrayish brown with numerous irregular white speckles. Supra-axillary gland coppery orange, pectoral and femoral glands grayish white, ventrolateral glands grayish white. Iris bicolored, upper half coppery orange and lower half grayish brown.

Coloration of holotype in preservative.

Dorsal background color dark brown scattered with irregular gray pigmentations. All markings, bars and spots become indistinct. Tympanum dark brown.

Ventral surface of throat, chest and abdomen grayish white; irregular dark brown speckles more distinct. Underside of limbs dark brown, irregular speckles grayish white. Supra-axillary, pectoral, and ventrolateral glands grayish white.

Variation.

Measurements and body proportions are listed in Table 2 . All the specimens showed relatively small differences in coloration and color patterns.

Distribution, ecology and conservation.

Leptobrachella yachangensis sp. nov. is currently only known from its type locality (Fig. 1 ; ca. 1240–1620 m a. s. l.). The new species inhabits clear-water rocky streams in primary forests surrounded by broad-leaved forest in granite landforms of karst region. Males were observed calling while perched in the rock crevices or on the leaves of dwarf shrubs near flowing seeps. The breeding season lasts from February to June according to our long-term observation. During the breeding season, a large number of vocalizing individuals can be observed in the streams. Leptobrachella yachangensis sp. nov. is under multiple potential human-induced pressures: potential wind power projects and eco-tourism development outside the protected area, artificial forest (such as Chinese fir forest) planting in the surrounding areas, and other activities may cause water pollution and habitat fragmentation. However, given that the current information on the distribution and threats of this species is still not fully understood, we recommend the new species be listed as Data Deficient ( DD) according to the International Union for Conservation of Nature ( IUCN) Red List Categories and Criteria.

Comparisons.

In the phylogenetic tree (Fig. 2 ), Leptobrachella yachangensis sp. nov. is most closely related to L. wumingensis (mean p - distance 6.5 %) and L. damingshanensis (mean p - distance 7.2 %), therefore, these two species are selected for detailed comparison. The new species differs from L. wumingensis by its presence of narrow fringes along lateral surfaces of toes (vs. absence of lateral fringes on toes), and differs from L. damingshanensis by its absence of webbing on toes (vs. presence of webbing on toes). Moreover, the new species can be also distinguished from the later two species by its presence of numerous conical tubercles bearing spines on dorsal surface (vs. absence of spines), the presence of transparent tiny conical spines on chest and abdomen in breeding males (vs. absence of spines), presence of dense irregular dark brown speckles on throat, chest and abdomen with (vs. absence of such speckles).

Compared with the 26 known congeners of the genus Leptobrachella occurring south of the Isthmus of Kra, by the presence of supra-axillary and ventrolateral glands, L. yachangensis sp. nov. can easily be distinguished from L. arayai , L. dringi , L. fritinniens , L. gracilis , L. hamidi , L. heteropus , L. kajangensis , L. kecil , L. marmorata , L. melanoleuca , L. maura , L. picta , L. platycephala , L. sabahmontana , and L. sola , all of which lack supra-axillary and ventrolateral glands; and by its distinctly larger male body size, SVL 25.7–28.2 mm, L. yachangensis sp. nov. differs from the smaller L. baluensis ( SVL 14.9–15.9 mm), L. brevicrus ( SVL 17.1–17.8 mm), L. bondangensis ( SVL 17.8 mm), L. fusca ( SVL 16.3 mm), L. itiokai ( SVL 15.2–16.7 mm), L. juliandringi ( SVL 17.0– 17.2 mm), L. mjobergi ( SVL 15.7–19.0 mm), L. natunae ( SVL 17.6 mm), L. parva ( SVL 15.0– 16.9 mm), and L. palmata ( SVL 14.4–16.8 mm); and even distinctly larger than female L. serasanae ( SVL 16.9 mm).

In having black spots on flanks, Leptobrachella yachangensis sp. nov. further differs from L. aerea , L. botsfordi , L. crocea , L. eos , L. firthi , L. isos , L. pallida , L. petrops , and L. tuberosa , all of which lack black spots on the flanks.

For the remaining 75 members of the genus Leptobrachella , males of the new species ( SVL 28.1–31.2 mm) differ from males of the larger L. nahangensis ( 40.8 mm), L. sungi ( 48.3–52.7 mm), and L. zhangyapingi ( 48.5–52.5 mm); and males of the smaller L. applebyi ( 19.6–22.3 mm), L. aspera ( 22.4 mm), L. feii ( 21.5–22.8 mm), L. melica ( 19.5–22.7 mm), L. niveimontis ( 22.5–23.6 mm), L. pluvialis ( 21.3–22.3 mm), and even distinctly larger than female L. korifi ( 22.7 mm).

Through its toes without webbing, Leptobrachella yachangensis sp. nov. can be distinguished from L. albomarginata , L. alpina , L. bashaensis , L. bijie , L. bidoupensis , L. bourreti , L. chishuiensis , L. dayaoshanensis , L. dong , L. dorsospina , L. dushanensis , L. guinanensis , L. fuliginosa , L. flaviglandulosa , L. graminicola , L. jinyunensis , L. khasiorum , L. lateralis , L. laui , L. liui , L. macrops , L. mangshanensis , L. maoershanensis , L. minima , L. murphyi , L. namdongensis , L. neangi , L. nokrekensis , L. nyx , L. pelodytoides , L. puhoatensis , L. purpurus , L. purpuraventra , L. pyrrhops , L. phiadenensis , L. phiaoacensis , L. pingbianensis , L. rowleyae , L. shangsiensis , L. shimentaina , L. sinorensis , L. suiyangensis , L. tamdil , L. tengchongensis , L. ventripunctata , L. verrucosa , L. wulingensis , L. xishuiensis , L. yongshunensis , L. yingjiangensis , L. yunkaiensis , L. yunyangensis , and L. yeae , all of which bear webbing on toes. In having toes with narrow lateral fringes, the new species can be distinguished from L. ardens , L. kalonensis , L. maculosa , L. oshanensis , L. shiwandashanensis , and L. tadungensis (vs. lateral fringes absent). In having transparent tiny conical spines on chest and abdomen in breeding males, the new species can be distinguished from L. aurantirosea , L. batxatensis , L. huynhi , and L. jinshaensis (vs. ventral skin smooth).

Figures

Figure 1. Distribution sites of Leptobrachella yachangensis sp. nov., L. damingshanensis and L. wumingensis.

Figure 2. Maximum Likelihood tree results from partial DNA sequences of the mitochondrial 16 S r RNA gene. Numbers before slashes indicate bootstrap support (BS) and numbers after slashes are Bayesian posterior probabilities (BPP). The ‘ - ’ represent BS ≤ 70 or BPP ≤ 0.90. Voucher before species name at the branch terminal corresponds to the voucher ID in Suppl. material 1: table S 1.

Figure 3. Morphological features of the holotype of Leptobrachella yachangensis sp. nov., NHMG 250402 in life. A. Dorsal view; B. Dorsolateral view; C. Lateral view; D. Ventral view; E. Ventral view of hand; F. Ventral view of foot.