Dayaoshan leaf-litter toad (Leptobrachella dayaoshanensis) from China at elevations of 1000-1600 m established as new to science

NEWS - Dayaoshan leaf-litter toad (Leptobrachella dayaoshanensis Chen, Yu, Meng & Qin sp. nov.) from Dayaoshan National Nature Reserve at elevations of 1000 and 1600 m in Jinxiu, Guangxi, China, was established as new to science based on phylogenetic analysis, morphology and bioacoustic data.

L. dayaoshanensis was found in the evergreen forest of Dayaoshan Mountain. Adult males made calls near rocky streams between 19:00 and 24:00, but there were also instances where calls were heard during the day. Calls were heard from early March to late April. Currently, the new species is only found within Dayaoshan National Nature Reserve.

The species name dayaoshanensis refers to the type locality, Dayaoshan Mountain. The researchers suggested the English name Dayaoshan Leaf Litter Toad and the Chinese name is Da Yao Shan Zhang Tu Chan (大瑶山掌突蟾).

L. dayaoshanensis can be distinguished from its relatives by its medium size (mean SVL 27.9 ± 0.7 mm, range 26.6–28.9 mm in males; 34.4 mm in females); rough dorsal surface with small tubercles and protuberances; body sides with irregular black spots and creamy white glands; ventral surface creamy white with sparse light brown spots and small irregular textures; brown throat and chest; rudimentary toe webbing; broad lateral margins of toes; distinct and continuous ventrolateral glandular line; tibiotarsal articulation reaching mid-eye point when feet are pressed forward; heels do not meet when thighs are pressed perpendicular to body; iris bicolor, with upper part coppery, gradually transitioning to silver below; and advertisement calls consisting of two types of models, with a dominant frequency of 4.2–6.8 kHz (21.0°C).

Phylogenetically, L. dayaoshanensis is closely related to Leptobrachella liui, Leptobrachella mangshanensis and Leptobrachella verrucosa. The new species differs from L. liui in having a relatively larger body size in females (SVL 34.4 mm vs. SVL 23.1–28.1 mm); HL/HW = 0.92 (vs. HL/HW = 1.01); ventral surface creamy yellow, with sparse light brown spots and irregular texture, throat and breast brown with scattered light cream spots (vs. breast and edges creamy white with dark brown spots); heels not meeting when thighs are pressed perpendicular to the body (vs. overlapping); successive dermal ridges below the toes (vs. separate dermal ridges); Different call durations (68–88 ms vs 26–78 ms) and dominant frequencies (4.2–6.8 kHz vs 4.8–5.5 kHz).

L. dayaoshanensis differs from L. mangshanensis in having a rough dorsal surface with small tubercles and ridges (vs. smooth dorsal skin with small orange tubercles and irregular dark brown stripes); broad lateral margins of toes (vs. narrow lateral margins of toes); distinct longitudinal ridges below toes (vs. indistinct longitudinal ridges below toes); tibiotarsal articulation reaching medial to eye (vs. tibiotarsal articulation reaching anterior edge of snout); brown throat and chest, and creamy white belly with sparse light brown spots and small irregular texture (vs. greyish white throat and belly with small white spots); bicolored iris, coppery upperparts, gradually turning to silver below (vs. bright orange upperparts, grayish cream below).

L. dayaoshanensis differs from L. verrucosa in having a relatively larger body size in males (SVL 26.6–28.9 mm vs. SVL 23.2–25.9 mm); head width greater than length (HW/HL = 1.08) (vs. head length slightly greater than head width, HW/HL = 0.95); eye diameter minus snout length (SNT/ED = 1.33) (vs. SNT/ED = 1.03); tongue with shallow notch at posterior end (vs. tongue deeply notched distally); tibiatarsal articulation reaching medial to eye when leg is pressed forward (vs. tibiotarsal articulation reaching anterior corner of eye); dorsal surface rough with small, prominent tubercles and ridges (vs. dorsal surface dull green with numerous conical tubercles, lacking spines, enlarged warts, or skin ridges); supratympanic line brown (vs. supratympanic line black); Lateral tufts of toes broad (vs. Lateral tufts of toes narrow); Throat and chest brown (vs. Creamy white); Relative toe length I < II < IV < III (vs. I = II = IV < III); Iris bicoloured, upperparts coppery, gradually turning to silvery below (vs. Upperparts coppery orange, Lowerparts greyish brown); Ventrolateral glandular line distinct and continuous (vs. Ventrolateral glandular line separate). Furthermore, L. dayaoshanensis is found at elevations above 1000 m, while L. verrucosa inhabits elevations of 500–600 m. Advertisement calls of the new species can be heard from early March to late April, while the breeding season of L. verrucosa lasts from April to June.

L. dayaoshanensis differs from Leptobrachella shimentaina and Leptobrachella yunkaiensis in having no lateral tufts on the toes (vs. having lateral tufts on the toes), heels not meeting when the thighs are pressed perpendicular to the body (vs. overlapping); from Leptobrachella flaviglandulosa in having heels not meeting when pressed (vs. overlapping), successive skin ridges under the toes (vs. separate skin ridges); from Leptobrachella bashaensis in having a relatively larger body size (SVL 26.6–28.9 mm in males, 34.4 mm in females vs. SVL 22.9–25.6 mm in males, 27.1 mm in females); broad lateral tufts of the toes (vs. narrow lateral tufts of the toes); from Leptobrachella maoershanensis having broad lateral toe tufts (vs. narrow lateral toe tufts), distinct successive skin ridges under the toes (vs. indistinct longitudinal ridges under the toes); from L. laui lacking lateral toe tufts (vs. moderate lateral tufts), ventral surface creamy yellow with sparse light brown spots and irregular texture, throat and breast brown with scattered light cream spots (vs. nearly spotless creamy white chest and belly); from Leptobrachella phiaoacensis having broad lateral toe tufts (vs. narrow lateral toe tufts), heels not meeting when thighs are pressed perpendicular to body (vs. overlapping), continuous ventrolateral glandular line (vs. separate ventrolateral glandular line), throat and breast brown (vs. creamy white).

In having supra-axillary and ventrolateral glands, L. dayaoshanensis differs from its relatives from the South of the Isthmus of Kra, Leptobrachella arayai, Leptobrachella dringi, Leptobrachella fritinniens, Leptobrachella gracilis, Leptobrachella hamidi, Leptobrachella heteropus, Leptobrachella kajangensis, Leptobrachella minor, Leptobrachella marmorata, Leptobrachella maura, Leptobrachella melanoleuca, Leptobrachella picta, Leptobrachella platycephala, Leptobrachella sabahmontana, and Leptobrachella sola (vs. absent in the latter species). Having a relatively larger body size (SVL 26.6–28.9 mm in males, 34.4 mm in females), L. dayaoshanensis is different from Leptobrachella baluensis (SVL 14.9–15.9 mm in males), Leptobrachella bondangensis (SVL 17.8 mm in males), Leptobrachella brevicrus (SVL 17.1–17.8 mm in males), Leptobrachella fusca (SVL 16.3 mm in males), Leptobrachella itiokai (SVL 15.2–16.7 mm in males), Leptobrachella juliandringi (SVL 17.0–17.2 mm in males), Leptobrachella mjobergi (SVL 15.7–19.0 mm in males), Leptobrachella natunae (SVL 17.6 mm in males), Leptobrachella palmata (SVL 14.4–16.8 mm in males), Leptobrachella parva (SVL 15.0–16.9 mm in males), and Leptobrachella serasanae (SVL 16.9 mm in females).

Of the remaining Leptobrachella species known from the northern Isthmus of Kra, by having an SVL of 26.6–28.9 mm in males, L. dayaoshanensis differs from the smaller Leptobrachella applebyi (19.6–22.3 mm), Leptobrachella ardens (21.3–24.7 mm), Leptobrachella bidoupensis (18.5–25.4 mm), Leptobrachella melica (19.5–22.7 mm), Leptobrachella niveimontis (22.5–23.6 mm), Leptobrachella pluvialis (21.3–22.3 mm), Leptobrachella rowleyae (23.4–25.4 mm); from the larger Leptobrachella dushanensis (31.9–32.9 mm), Leptobrachella nahangensis (40.8 mm), Leptobrachella sungi (48.3–52.7 mm), and Leptobrachella zhangyapingi (45.8–52.5 mm).

In addition, by having broad lateral margins on the toes, L. dayaoshanensis differs from L. applebyi, L. ardens, Leptobrachella crocea, Leptobrachella kalonensis, Leptobrachella lateralis, Leptobrachella macrops, Leptobrachella maculosa, L. melica, L. nahangensis, Leptobrachella namdongensis, Leptobrachella neangi, Leptobrachella nyx, Leptobrachella oshanensis, Leptobrachella pallida, L. pluvialis, Leptobrachella pyrrhops, L. rowleyae, Leptobrachella shiwandashanensis, Leptobrachella tadungensis, Leptobrachella tuberosa and Leptobrachella ventripunctatus (vs. no lateral margins on the toes). Having black spots on the flanks, L. dayaoshanensis differs from Leptobrachella aerea, Leptobrachella botsfordi, L. crocea, Leptobrachella eos, Leptobrachella firthi, Leptobrachella graminicola, Leptobrachella isos, L. pallida, Leptobrachella petrops and L. tuberosa (vs. none).

DESCRIPTION OF HOLOTYPE

Adult male, head width larger than length (HW/HL = 1.08); snout protruding, projecting over the lower jaw; nostril oval, closer to tip of snout than eye; canthus rostralis rounded; loreal region sloping; interorbital area flat; pupil vertical; eye diameter less snout length (ED/SNT = 0.75); internarial distance less than interorbital distance (IN/IOD = 0.77); tympanum distinct, rounded and concave, significantly less than eye diameter, TD/ED = 0.43; distinct and raised supratympanic fold from the corner of eye to supra-axillary gland; vomerine teeth absent; tongue with a shallow notch at the posterior tip.

Tips of fingers slightly swollen; relative finger lengths I < II < IV < III; nuptial pad absent; subarticular tubercles absent; prominent inner palmar tubercle and very small outer palmar tubercle; finger webbing and dermal fringes absent. Tips of toes rounded, slightly swollen but less than toe width; relative toe lengths I < II < V < III < IV; subarticular tubercles absent, instead by consecutive dermal ridges; large and elongated inner metatarsal tubercle; outer metatarsal tubercle absent; toe webbing rudimentary; toes lateral fringes well-developed, half of phalange in width; TIB/SVL = 0.42; tibia–tarsal articulation reaching the medium of eye when the leg is pressed forward; heels not meeting when thighs are appressed at right angles to body.

Dorsal surface rough with small, raised tubercles and ridges; ventral surface smooth without tubercles; pectoral glands oval and creamy white, ~1.2 mm in diameter; femoral glands oval, ~1.3 mm in diameter, closer to knee than to vent; supra-axillary glands distinct and rounded, ~1.0 mm in diameter; continued ventrolateral glandular line distinct; limbs surface without tubercles.

Color of holotype in life

Dorsum saffron yellow with distinct brown markings, a brown triangle between eyes, a brown “W” marking on shoulder, and a brown “Λ” marking on lower back; tympanum pale brown; supratympanic line brown from posterior corner of eye to supra-axillary glands; brown bars on upper lip wide; flanks with irregular black spots and creamy yellow glands; three transverse, dark-brown bars distinct on dorsal surface of hindlimbs; elbows, upper arms and tibiotarsal surfaces light tangerine; ventral surface creamy white, with sparse, light-brown spots and irregular, tiny textures; throat and chest brown; pectoral and femoral glands creamy white, supra-axillary glands light tangerine; pupil black; iris bicolored, upper half copper, gradually transitioning to silver in lower half.

Color of holotype in preservative

Dorsum and limbs surfaces faded to uniform grey; brown triangular marking distinctly visible between eyes; irregular black spots on flanks distinct; throat, chest grey, and belly creamy white; pectoral, femoral, supra-axillary, and ventrolateral glands creamy white; dark bars on limbs, fingers, and toes distinct; elbow pale orange; upper arm and tibiotarsus faded to grey.

Variation

The presence of tubercles or ridges on the dorsum varies, as do the irregular markings. Certain specimens exhibit a lighter mustard color. Additionally, the margin of the throat displays creamy-white tubercles in some individuals.

Measurements of holotype

(in mm). SVL 27.6, HL 8.6, HW 9.3, SNT 4.0, ED 3.0, IOD 3.1, TD 1.3, TED 1.2, IN 2.4, TIB 11.7, FLL 12.2, THL 17.8, ML 6.7, HLL 39.4, FG-knee 4.7.

Original research

Yu G-D, Qin K, Meng T, Li P, Peng W-X, Chen W-C (2024). A new species of the genus Leptobrachella (Amphibia, Anura, Megophryidae) from Dayaoshan National Nature Reserve, Guangxi, China. ZooKeys 1219: 105-122, DOI:10.3897/zookeys.1219.121027

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