Leptobrachella dayaoshanensis Chen, Yu, Meng & Qin, 2024

Yu, Gui-Dong, Qin, Kun, Meng, Tao, Li, Peng, Peng, Wan-Xiao & Chen, Wei-Cai, 2024, A new species of the genus Leptobrachella (Amphibia, Anura, Megophryidae) from Dayaoshan National Nature Reserve, Guangxi, China, ZooKeys 1219, pp. 105-122 : 105-122

Leptobrachella dayaoshanensis Chen, Yu, Meng & Qin sp. nov.

Fig. 5 A – E

Leptolalax liui Fei & Ye, 1990 (Chresonymy): Fei et al. 1992; Fei et al. 2012; Mo et al. 2014.

Type material.

Holotype • NNU 20210318 , adult male, collected at the Dayaoshan National Nature Reserve (DYS), Jinxiu County, Guangxi, China (24.153 ° N, 110.213 ° E; elevation 1132 m), collected by Wei-Cai Chen on 12 March 2021 . Paratypes • NNU 20210319 –26, NNU 20210328 –33, 14 adult males, and NNU 20210327 , one adult female, collected at the same locality as holotype on 12 March 2021 by Wei-Cai Chen .

Etymology.

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

Diagnosis.

Leptobrachella dayaoshanensis sp. nov. can be distinguished from its congeners by a combination of the following characters: (1) medium size (SVL mean 27.9 ± 0.7 mm, range 26.6–28.9 mm in males; 34.4 mm in female); (2) dorsal surface rough with small, raised tubercles and ridges; (3) flanks with irregular black spots and creamy-white glands; (4) ventral surface creamy-white with sparse, light-brown spots and irregular, tiny textures; (5) brown throat and chest; (6) rudimentary toe webbing; (7) wide toes lateral fringes; (8) distinct continued ventrolateral glandular line; (9) tibiotarsal articulation reaching the midpoint of eye when the leg is pressed forward; (10) heels not meeting when thighs are appressed at right angles to body; (11) bicolored iris, with upper half copper, gradually transitioning to silver in lower half; and (12) advertisement calls consisting of two types models, with dominant frequencies of 4.2–6.8 kHz (21.0 ° C).

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 (Fig. 5 A – F ).

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 (Fig. 5 A – F ).

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 (Fig. 5 A – F ).

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.

Measurements of the type series are presented in Table 2 . The presence of tubercles or ridges on the dorsum varies, as do the irregular markings (Suppl. material 1: fig. S 1). Certain specimens exhibit a lighter mustard color. Additionally, the margin of the throat displays creamy-white tubercles in some individuals (Suppl. material 1: fig. S 2).

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.

Ecology and distribution.

Leptobrachella dayaoshanensis sp. nov. was discovered in the evergreen forest at Mount Dayaoshan, at elevations between 1,000 and 1,600 m. Our observations revealed that adult males of this species were found calling near rocky streams between 19: 00 and 24: 00 h during our survey. Interestingly, there were also instances where advertisement calls could be heard during the daytime. We noted that the advertisement calls were audible from early March until the end of April. Presently, L. dayaoshanensis sp. nov. is only found within the Dayaoshan National Nature Reserve.

Comparisons.

Leptobrachella dayaoshanensis sp. nov. can be distinguished from other Leptobrachella species by its body size (males: SVL 26.6–28.9 mm; female: 34.4 mm); small, raised tubercles and ridges on dorsum; presence of irregular black spots on flanks; creamy-yellow ventral surface with sparse, light-brown spots and irregular textures; rudimentary toe webbing; wide lateral fringes; tongue with a shallow notch; brown throat and chest; distinct continued ventrolateral glandular line; tibiotarsal articulation reaching the midpoint of eye; heels not meeting when thighs are appressed at right angles to body; and bicolored iris, with the upper half being copper, gradually transitioning to silver in the lower half. Furthermore, the species can be identified by its unique advertisement calls (Fig. 4 , Suppl. material 2: table S 4).

Phylogenetically, L. dayaoshanensis sp. nov. is closely related to L. liui , L. mangshanensis , and L. verrucosa (Fig. 3 ). Morphologically, L. dayaoshanensis sp. nov. differs from L. liui in having a relatively larger body size in female (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 textures, brown throat and chest with scattered, light, creamy spots (vs chest and margins creamy white with dark-brown spots); heels not meeting when thighs are appressed at right angles to body (vs overlapped); consecutive dermal ridges under toes (vs discrete 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). Leptobrachella dayaoshanensis sp. nov. differs from L. mangshanensis in having a rough dorsal surface with small, raised tubercles and ridges (vs dorsal skin smooth with small orange tubercles and irregular, dark-brown stripes); wide toe lateral fringes (vs narrow toe lateral fringes); distinct longitudinal ridges under toes (vs indistinct longitudinal ridges under toes); tibiotarsal articulation reaching the medium of eye (vs tibiotarsal articulation reaching anterior margin of snout); brown throat and chest, and creamy-white belly with sparse, light-brown spots and irregular, tiny textures (vs greyish-white throat and belly with little white speckles); bicolored iris, upper half copper, gradually transitioning to silver in lower half (vs bright-orange upper, greyish cream below). Leptobrachella dayaoshanensis sp. nov. differs from L. verrucosa in having relatively larger body size in males (SVL 26.6–28.9 mm vs SVL 23.2–25.9 mm); head width larger than length (HW / HL = 1.08) (vs head length slightly larger than head width, HW / HL = 0.95); eye diameter less snout length (SNT / ED = 1.33) (vs SNT / ED = 1.03); tongue with a shallow notch at the posterior tip (vs tongue deeply notched distally); tibiatarsal articulation reaching the medium of eye when the leg is pressed forward (vs tibiotarsal articulation reaches to anterior corner of eye); rough dorsal surface with small, raised tubercles and ridges (vs shagreened dorsal surface with numerous conical tubercles, lacking spines, enlarged warts, or skin ridges); brown supratympanic line (vs black supratympanic line); wide toe lateral fringes (vs narrow toe lateral fringes); brown throat and chest (vs creamy white); relative finger lengths I <II <IV <III (vs I = II = IV <III); bicolored iris, upper half copper, gradually transitioning to silver in lower half (vs upper half coppery orange, lower half greyish brown); distinct continued ventrolateral glandular line (vs discrete ventrolateral gland line). Furthermore, L. dayaoshanensis sp. nov. is found at elevations over 1,000 m, whereas L. verrucosa inhabits elevations of 500– 600 m. The advertisement calls of the new species can be heard from early March to the end of April, while the breeding season of L. verrucosa lasts from April to June according to Lin et al. (2022).

Leptobrachella dayaoshanensis sp. nov. differs from L. shimentaina and L. yunkaiensis in lacking lateral fringes on fingers (vs presence of lateral fringes on fingers), heels not meeting when thighs are appressed at right angles to body (vs overlapped); from L. flaviglandulosa in having heels not meeting when adpressed (vs overlapped), consecutive dermal ridges under toes (vs discrete dermal ridges); from L. bashaensis in having relatively larger body size (SVL 26.6–28.9 mm in males, 34.4 mm in female vs SVL 22.9–25.6 mm in males, 27.1 mm in female); wide toe lateral fringes (vs narrow toe lateral fringes); from L. maoershanensis in having wide toe lateral fringes (vs narrow toe lateral fringes), distinct consecutive dermal ridges under toes (vs indistinct longitudinal ridges under toes); from L. laui in lacking finger lateral fringes (vs presence of moderate lateral fringes), creamy-yellow ventral surface with sparse, light-brown spots and irregular textures, brown throat and chest with scattered, light-creamy spots (vs near immaculate creamy-white chest and belly); from L. phiaoacensis in having wide toe lateral fringes (vs narrow toe lateral fringes), heels not meeting when thighs are appressed at right angles to body (vs overlapped), continued ventrolateral glandular line (vs discrete ventrolateral gland line), brown throat and chest (vs creamy white).

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

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

Furthermore, in having wide lateral fringes on toes, L. dayaoshanensis sp. nov. differs from L. applebyi , L. ardens , L. crocea , L. kalonensis , L. lateralis , L. macrops , L. maculosa , L. melica , L. nahangensis , L. namdongensis , L. neangi , L. nyx , L. oshanensis , L. pallida , L. pluvialis , L. pyrrhops , L. rowleyae , L. shiwandashanensis , L. tadungensis , L. tuberosa and L. ventripunctatus (vs absent lateral fringes on toes). In having black spots on flanks, L. dayaoshanensis sp. nov. differs from L. aerea , L. botsfordi , L. crocea , L. eos , L. firthi , L. graminicola , L. isos , L. pallida , L. petrops and L. tuberosa (vs absent).

Leptobrachella dayaoshanensis sp. nov. differs from its congeners in the dominant frequency of 4.2–6.8 kHz (21.0 ° C) (Suppl. material 2: table S 4).

Figures

Figure 3. BI trees based on 16 S fragments with Bayesian posterior probabilities / bootstrap supports on branches. Bayesian posterior probabilities, upper half, > 0.95 = grey, 1 = black; bootstrap supports, lower half, > 70 % <90 % = grey, > 90 % = black).

Figure 4. Advertisement call spectrograms of Leptobrachella dayaoshanensis sp. nov.

Figure 5. The holotype of Leptobrachella dayaoshanensis sp. nov. A dorsal view B ventral view C dorsolateral view D calling in the field E ventral view of hand F ventral view of foot.