Leptobrachella chishuiensis, Li & Liu & Wei & Wang, 2020

Li, Shi-Ze, Liu, Jing, Wei, Gang & Wang, Bin, 2020, A new species of the Asian leaf litter toad genus Leptobrachella (Amphibia, Anura, Megophryidae) from southwest China, ZooKeys 943, pp. 91-118 : 91

Leptobrachella chishuiensis sp. nov. Figs 4 , 5 , 6 ; Tables 1, 2, 3, 4, 5

Type material.

Holotype. CIBCS20190518047, adult male (Figs 4 , 5 ), collected by Shi-Ze Li in Chishui National Nature Reserve (28.436708N, 105.997794E, ca. 465 m a. s. l.), Chishui City, Guizhou Province, China on 18 May 2019.

Paratypes. Six adult males and one adult female from Chishui City, Guizhou Province, China, collected by Shize LI and Jing LIU. One female CIBCS20190518046 and two adult males CIBCS 20190518048 and CIBCS20190518049 collected by Jing LIU on 18 May 2019, four adult males CIBCS 20190518042, CIBCS 20190518043, CIBCS20190518044 and CIBCS20190518045 collected by Shize LI on 18 May 2019.

Diagnosis.

Leptobrachella chishuiensis sp. nov. is assigned to the genus Leptobrachella based on molecular phylogenetic analyses and the following morphological characters: small body size; having an elevated inner metacarpal tubercle; having macro-glands on body (including supra-axillary, femoral andventrolateral glands); lacking vomerine teeth; having small tubercles on eyelids; anterior tip of snout with whitish vertical bar ( Dubois 1983; Matsui 1997, 2006; Lathrop et al. 1998; Delorme et al. 2006; Das et al. 2010; Luo et al. 2020).

Leptobrachella chishuiensis sp. nov. could be distinguished from its congeners by a combination of the following characters: (1) small body size (SVL 30.8-33.4 mm in seven adult males, and 34.2 mm in one adult female); (2) dorsal skin shagreened, some of the granules forming longitudinal short skin ridges; (3) tympanum distinctly discernible, slightly concave; (4) internasal distance longer than interorbital distance; (5) supra-axillary, femoral, pectoral and ventrolateral glands distinctly visible; (6) absence of webbing and lateral fringes on fingers; (7) toes with rudimentary webbing and shallow lateral fringes; (8) relative finger lengths II <IV <I <III; (9) heels overlapped when thighs are positioned at right angles to the body; and (10) tibia-tarsal articulation reaches the tympanum.

Description of holotype.

Measurements in mm. Adult male (CIBCS20190518047). SVL 32.4. Head length slightly longer than head width (HDL/HDW ratio 1.04); snout slightly protruding, projecting slightly beyond margin of the lower jaw; nostril closer to snout than eye; canthus rostralis gently rounded; loreal region slightly concave; interorbital space flat, internarial distance longer than interorbital distance (IND/IOD ratio 1.23); pineal ocellus absent; vertical pupil; snout length larger than eye diameter; tympanum distinct, rounded, and slightly concave, diameter smaller than that of the eye (TMP/ED ratio 0.57); upper margin of tympanum in contact with supratympanic ridge; distinct black supratympanic line present; vomerine teeth absent; tongue notched behind; supratympanic ridge distinct, extending from posterior corner of eye to supra-axillary gland.

Tips of fingers rounded, slightly swollen; relative finger lengths II <IV <I <III (FIL/FIIL ratio 1.1, FIVL/FIIL ratio 1.03); absence of webbing; nuptial pad and subarticular tubercles absent; inner palmar tubercle large, rounded separated from small, round outer palmar tubercle.

Hindlimbs slender, tibia 49% of snout-vent length; heels overlapped when thighs are positioned at right angles to the body, tibiotarsal articulation reaching tympanum when leg stretched forward; tibia length slightly longer than thigh length; relative toe lengths I <II <V <III <IV; tips of toes rounded, slightly dilated; subarticular tubercle small, distinct at the base of each toes; toes without webbing; narrow lateral fringes present on all toes; inner metatarsal tubercle present, large, oval, outer metatarsal tubercle absent; dorsal surface shagreened and granular, some of the granules forming short longitudinal folds on the flank of dorsal; ventral skin smooth; dense tiny granules present on surface of chest and ventral surface of thigh and tibia; pectoral gland and femoral gland oval, distinctly visible. Ventrolateral gland distinctly visible and forming an incomplete line.

Colouration of holotype in life.

Dorsum brown, with small, distinct darker brown markings and spots and scattered with irregular light orange pigmentation. A dark brown inverted triangular pattern between anterior corner of eyes. Tympanum brown, a dark brown bar above tympanum, and a dark brown bar under the eye; transverse dark brown bars on dorsal surface of limbs; distinct dark brown blotches on flanks from groin to axilla, longitudinally in two rows; elbow and upper arms with dark bars and distinct coppery orange coloration; fingers and toes with distinct dark bars. Ventral surface of throat grey purple, chest and belly white, presence of distinct nebulous greyish speckling on flanks; ventral surface of limbs grey purple. Supra-axillary gland, femoral, pectoral and ventrolateral glands white (Fig. 5 ).

Preserved holotype colouration.

Dorsum of body and limbs fade to dark brown; transverse bars on limbs become more distinct ventral surface of body and limbs fade to greyish white. Supra-axillary, femoral, pectoral and ventrolateral glands fade to greyish white (Fig. 4 ).

Variations.

Morphological measurements were showed in Table 2 . All specimens were similar in morphology but some individuals different from the holotype in color pattern. In some adult males, a dark brown inverted triangular pattern between anterior corner of eyes, in connected to the dark brown W-shaped marking on interorbital region (Fig. 6A ); in adult female, the color of dorsum is blacker (Fig. 6B ) and some patchiness on the chest and the flank of belly (Fig. 6C ); in some adult males, the throat and bell creamy and white patchiness sparse on the ventral surface of limbs (Fig. 6D ); in some specimens, the tibiotarsal articulation reaching tympanum to eye when leg stretched forward.

Advertisement call.

A total of 32 advertisement calls of Leptobrachella chishuiensis sp. nov. were recorded in Chishui City, Guizhou Province, China on 18 May 2019 between 21:00-22:00. The call description is based on recordings of the holotype CIBCS20190518047 (Fig. 7 ) from a branch of bush nearby a stream. Each call contains 1-4 notes (mean 2.34 ± 0.827, N = 32). Call duration was 75-353 ms (mean 200 ± 67, N = 32). Call interval was 8-98 ms (mean 60 ± 21, N = 31) with a peak frequency was 6140.15 ± 69.35 (6064-6284 Hz, N = 32). Each note had a duration of 52-950 ms (mean 104 ± 107, N = 69), and the intervals between notes had a duration of 0. 1-25 ms (mean 5.3 ± 8.5, N = 37). Amplitude modulation within note was apparent, beginning with high energy pulses then decreasing towards the end of each note.

Secondary sexual characteristics.

Adult males with a large subgular vocal sac, and nupital pads and spines absent.

Comparisons.

The new species was compared with 52 congeners on morphology (Table 4 ). By having small body size (SVL 30.8-33.4 mm in seven adult males, and 34.2 mm in one adult female), Leptobrachella chishuiensis sp. nov. differs from the larger L. bourreti (42.0-45.0 mm in females), L. eos (33.1-34.7 mm in males and 40.7 in female), L. lateralis (36.6 mm in females), L. nahangensis (40.8 mm in male), L. nyx (37.0-41.0 mm in females), L. platycephala (35.1 mm in male), L. sungi (48.3-52.7 mm in males and 56.7-58.9 mm in females), and L. zhangyapingi (45.8-52.5 mm in males), and differs from the smaller L. aerea (25.1-28.9 mm in males), L. alpina (24.0-26.4 mm in males), L. applebyi (19.6-22.3 mm in males), L. ardens (21.3-24.7 mm in males), L. baluensis (14.9-15.9 mm in males), L. bidoupensis (18.5-25.4 mm in males), L. bijie (29.0-30.4 mm in males), L. bondangensis (17.8 mm in male), L. brevicrus (17.1-17.8 mm in males), L. crocea (22.2-27.3 mm in males), L. frthi (26.4-29.2 mm in males), L. fuliginosa (28.2-30.0 mm in males), L. fusca (16.3 mm in male), L. isos (23.7-27.9 mm in males), L. itiokai (15.2-16.7 mm in males), L. juliandringi (17.0-17.2 mm in males and 18.9-19.1 mm in females), L. khasiorum (24.5-27.3 mm in males), L. lateralis (26.9-28.3 mm in males), L. laui (24.8-26.7 mm in males), L. liui (23.0-28.7 mm in males), L. macrops (28.0-29.3 mm in males), L. maculosa (24.2-26.6 mm in males), L. mangshanensis (22.22-27.76 mm in males), L. melica (19.5-22.8 mm in males), mjobergi (15.7-19.0 mm in males), L. natunae (17.6 mm in male), L. pallida (24.5-27.7 mm in males), L. palmata (14.4-16.8 mm in males), L. parva (15.0-16.9 mm in males), L. petrops (23.6-27.6 mm in males), L. pluvialis (21.3-22.3 mm in males), L. purpuraventra (27.3-29.8 mm in males), L. puhoatensis (24.2-28.1 mm in males), L. purpura (25.0-27.5 mm in males), L. rowleyae (23.4-25.4 mm in males), L. shangsiensis (24.9-29.4 mm in males), L. suiyangensis (28.7-29.7 mm in males), L. tadungensis (23.3-28.2 mm in males), L. tengchongense (23.9-26.0 mm in males), L. tuberosa (24.4-29.5 mm in males), L. ventripunctata (25.5-28.0 mm in males), L. wuhuangmontis (25.6-30.0 mm in males), L. yingjiangensis (25.7-27.6 mm in males), and L. yunkaiensis (25.9-29.3 mm in males).

By supra-axillary and ventrolateral glands present, Leptobrachella chishuiensis sp. nov. differs 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 (vs. absent in the latter).

By having black spots on flanks, Leptobrachella chishuiensis sp. nov. differs from L. aerea , L. botsfordi , L. frthi , and L. tuberosa (vs. lacking in the latter).

By toes with rudimentary webbing, Leptobrachella chishuiensis sp. nov. differs from L. kalonensis and L. oshanensis (vs. lacking webbing on toes in the latter), and differs from L. pelodytoides (vs. toes with wide webbing in the latter).

By having shallow lateral fringes on toes, Leptobrachella chishuiensis sp. nov. differs from L. aerea , L. frthi , L. liui , and L. yunkaiensis (vs. having prominently wide lateral fringes on toes in the latter), and differs from L. kalonensis , L. macrops , L. minima , L. nyx , L. oshanensis , L. pyrrhops , and L. tuberosa (vs. lacking lateral fringes on toes in the latter).

By having dorsal surface shagreened and granular, lacking enlarge tubercles or warts, Leptobrachella chishuiensis sp. nov. differs from the following species: L. bourreti (dorsum smooth with small warts), L. fuliginosa (dorsum smooth with fine tubercles), L. liui (dorsum with round tubercles), L. macrops (dorsum roughly granular with large tubercles), L. maoershanensis (dorsum shagreened with tubercles), L. minima (dorsum smooth), L. nyx (dorsum with round tubercles), L. pelodytoides (dorsum with small, smooth warts), L. tamdil (dorsum weakly tuberculate, with low, oval tubercles), L. tuberosa (dorsum higly tuberculate), L. yunkaiensis (dorsum with raised warts), and L. wuhuangmontis (dorsum rough with conical tubercles).

By the finger II <I, Leptobrachella chishuiensis sp. nov. differs from L. tamdil (vs. II> I in the latter).

By head length slightly longer than wide, Leptobrachella chishuiensis sp. nov. differs from L. namdongensis (vs. head wider than long in the latter).

Six Leptobrachella species were reported to be distributed in Guizhou Province, China, they are: L. liui , L. oshanensis , L. purpuraventra , L. bijie , L. ventripunctata , and L. suiyangensis ( Fei et al. 2012; Li et al. 2016; Wang et al. 2019; Luo et al. 2020). We make a comparative note between them and the new species as follows. Leptobrachella chishuiensis sp. nov. differs from L. liui by having shallow lateral fringes on toes (vs. wide lateral fringes on the toes in the latter), dorsal surface shagreened with small granules, lacking enlarge tubercles or warts (vs. dorsum with round tubercles in the latter); from L. oshanensis by having rudimentary webbing on the toes (vs. lack webbing on the toes in the latter), having shallow lateral fringes on toes (vs. lacking lateral fringes on the toes in the latter), from L. suiyangensis by heels overlapping when thighs are positioned at right angles to the body (vs. just meeting in the latter), tibia-tarsal articulation reaches tympanum or tympanum to eye (vs. reaches to the anterior corner of eye in the latter); from L. ventripunctata by bigger body size (SVL 30.8-33.4 mm in adult males vs. SVL 25.5-28.0 mm in males in the latter), chest and belly without large dark brown spots (vs. with large dark brown spots in the latter).

Leptobrachella chishuiensis sp. nov. is genetically closer to L. bijie and L. purpuraventra . The new species differs from L. bijie by the following characters: larger body size (SVL 30.8-33.4 mm in males vs. SVL 29.0-30.4 mm in males in the latter), internasal distance longer than interorbital distance (vs. equal to interorbital distance in the latter), heels overlapping (vs. just meeting in the latter), tibia-tarsal articulation reaches the tympanum or tympanum to eye (vs. reaching the region between middle of eye to anterior corner of eye in the latter), one call contains 1-4 notes (vs. 2 notes in each call in the latter), having shorter call interval (60 ± 21, N = 31 in the new species vs. 101.9 ± 6.4, N = 33 in the latter), having significantly higher value of SVL in males, and having significantly higher value of HDL, HDW, SL, IND, IOD, TEY, TL and FL to SVL in males (all P-values <0.05; Table 5 ).

Leptobrachella chishuiensis sp. nov. differs from L. purpuraventra by larger body size (SVL 30.8-33.4 mm in seven adult males vs. SVL 27.3-29.8 mm in eleven adult males in the latter), tibia-tarsal articulation reaches the tympanum or tympanum to eye (vs. reaching the middle of eye in the latter), the call contains 1-4 notes (vs. 2 notes in each call in the latter), having longer call duration (200 ± 67, N = 32 vs. 192.2 ± 13.0 as the longest call duration in L. purpuraventra ), shorter call interval (60 ± 21, N = 31 vs. 90.8 ± 5.6, N = 20 as the shortest call interval in L. bijie ), having significantly higher value of SVL in males, and having significantly higher value of SVL, HDL,HDW, SL, IOD, ED, TYD, LAL, TL and FL to SVL in males (all P-values <0.05; Table 5 ).

Ecology.

Leptobrachella chishuiensis sp. nov. is known from the type locality, Chishui National Nature Reserve (28.383333-28.45N, 105.05-109.75E), Chishui City, Guizhou Province, China at elevations between 270-604 m a. s. l. This new species is found in bamboo forest nearby the streams (Fig. 8 ), and four sympatric amphibian species, i.e. Megophrys omeimontis , Odorrana margaratae (Liu, 1950), Zhangixalus omeimontis (Stejneger, 1924), and Rana omeimontis Ye & Fei, 1993 were found nearby.

Etymology.

This specific name chishuiensis refers to the distribution of this species, Chishui City, Guizhou Province, China. We propose the common English name "Chishui leaf litter toads" (English) and its Chinese as "Chi Shui Zhang Tu Chan ( 赤水掌突蟾)”.

Figures

Figure 4. The holotype specimen CIBCS 20190518047 of Leptobrachella chishuiensis sp. nov. in preservative A dorsal view B ventral view C frontal view of tongue D ventral view of hand E ventral view of foot.

Figure 5. Photos of the holotype CIBCS 20190518047 of Leptobrachella chishuiensis sp. nov. in life A dorsal view B ventral view C dorsal view of hand D ventral view of hand E ventral view of foot.

Figure 6. Colour variation in Leptobrachella chishuiensis sp. nov. A dorsal view of the male specimen CIBCS 20190518042 B dorsal view of the female specimen CIBCS 20190518046 C ventral view of the female specimen CIBCS 20190518046 D ventral view of the female specimen CIBCS 20190518049.

Figure 7. Advertisement calls of the holotype CIBCS 20190518047 of Leptobrachella chishuiensis sp. nov. A waveform showing one second contains 4 calls B sonogram showing one second contains 4 calls C waveform showing 0.4 second contains a call D sonogram showing 0.4 second contains a call.

Figure 8. Habitats of Leptobrachella chishuiensis sp. nov. in the type locality Chuishui National Nature Reserve, Chishui City, Guizhou Province, China A landscape of montane forests in the type locality B a mountain stream in the type locality (insert holotype CIBCS 20190518047 in life in the field).