Leptolalax tengchongensis, Yang, Jian-Huan, Wang, Ying-Yong, Chen, Guo-Ling & Rao, Ding-Qi, 2016

Yang, Jian-Huan, Wang, Ying-Yong, Chen, Guo-Ling & Rao, Ding-Qi, 2016, A new species of the genus Leptolalax (Anura: Megophryidae) from Mt. Gaoligongshan of western Yunnan Province, China, Zootaxa 4088 (3), pp. 379-394 : 384-391

Leptolalax tengchongensis sp. nov.

Holotype. SYS a004600, adult male, calling at the base of a shrub about 3 m away from a rocky stream. The stream was 3–4 m wide, flowing through a montane evergreen broadleaf forest at Linjiapu substation of the Tengchong Section of Gaoligongshan National Nature Reserve, Tengchong County, Yunnan Province, China (25°17'51.26'' N, 98°42'03.93'' E, 2100 m above sea level), collected at 23:40 h on 16 May 2015 by J.H. Yang.

Paratypes. SYS a004596, adult male, calling under rock by the side of the stream, from the same locality as holotype, collected by J.H. Yang on 29 April 2014; SYS a004597, a004599 and a004601, three adult males, data identical to holotype; SYS a004598 and a004602, two adult females, collection data identical to holotype.

Etymology. The specific epithet, “ tengchongensis ”, is in reference to the type locality, Tengchong County of Yunnan Province, China. For the common name, we suggest “Tengchong Leaf Litter Toad”.

Diagnosis. The new species is assigned to the genus Leptolalax by the possession of the following morphological characters considered to be diagnostic for the genus: (1) comparatively small size; (2) rounded finger tips, the presence of an elevated inner palmar tubercle not continuous to the thumb; (3) presence of macroglands on body including supra-axillary, pectoral, femoral and ventrolateral glands; (4) vomerine teeth absent; (5) tubercles on eyelids present and (6) 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); and it is further assigned to the subgenus Lalos based on the presence of a ventrolateral gland (Ohler et al. 2011). Leptolalax tengchongensis sp. nov. can be distinguished from its congeners by a combination of the following characters: (1) small size (SVL 23.9–26.0 mm in males, 28.8–28.9 mm in females); (2) dorsal skin shagreened and scattered with fine, round reddish tubercles; (3) toes with rudimentary webbing and narrow lateral fringes; (4) tympanum distinctly discernible, almost entirely black; (5) ventrolateral glands indistinct; (6) flanks with several distinct and large dark blotches; (7) ventral side whitish, scattered with distinct irregular dark speckling; (8) iris not bicolored, uniformly dark brown and scattered with minute, coppery reticulations throughout.

Description of holotype. SYS a004600 ( Fig. 3 , 4 ), adult male, body size small (SVL 26.0 mm), head width equal to head length; snout slightly protruding, projecting slightly beyond margin of the lower jaw; nostril equidistant between snout and eye; canthus rostralis gently rounded; loreal region slightly concave; interorbital space flat, larger (IOD 3.2 mm) than upper eyelid (2.5 mm in width) and internarial distance (2.6 mm); pineal ocellus absent; vertical pupil; eye diameter smaller than snout length; tympanum distinct, round, diameter (TMP 1.5 mm) smaller than that of the eye (EYE 3.3 mm), and larger than tympanum-eye distance (TEY 0.9 mm); tympanic rim slightly elevated relative to skin of temporal region; vomerine teeth absent; vocal sac openings slitlike, located posterolaterally on floor of mouth in close proximity to the margins of the mandible; tongue long, wide, with a small shallow notch at posterior tip; supratympanic ridge distinct, extending from eye to supra-axillary gland; tubercles present on supratympanic ridge. Tips of fingers rounded, slightly swollen; relative finger lengths I = II = IV <III; nuptial pad absent; subarticular tubercles absent; a large, round inner palmar tubercle distinctly separated from small, round outer palmar tubercle; finger webbing and dermal fringes absent ( Fig. 3 D). Tips of toes like fingers; relative toe length I <II <V <III <IV; subarticular tubercles absent; distinct dermal ridges present under the 3rd to 5th toes; large, oval inner metatarsal tubercle present, outer metatarsal tubercle absent; toe webbing rudimentary; narrow lateral fringes present on all toes ( Fig. 3 C). Tibia 47% of snout-vent length; tibiotarsal articulation reaches to middle of eye. Skin on dorsum shagreened and scattered with fine, round tubercles; ventral skin smooth; pectoral gland medium size, round, 0.8 mm diameter; femoral gland large, oval, 1.8 mm diameter, situated on posteroventral surface of thigh, closer to knee than to vent; supra-axillary gland raised, 1.1 mm diameter. Ventrolateral gland faintly visible as small white dots forming an incomplete line.

Coloration of holotype in life. Dorsal surface brown with distinct darker brown markings and scattered with light coppery and irregular spots ( Fig. 4 ); V-shaped interorbital marking connected to the W-shaped marking between axillae, and continuously connected to the inverted V-shaped, irregular marking above sacrum; fine, distinct reddish tubercles on upper eyelids, snout, head, dorsal surfaces of body and limbs, those on lower flanks somewhat whitish; anterior upper lip with distinct blackish brown patches; blackish brown line along canthus rostralis, through eye, and continuing below supratympanic ridge, terminating above arm insertion, encompassing posterior edge of nare and most of tympanum; a blackish brown spot present on loreal region; transverse dark brown bars on dorsal surface of limbs; large, black blotches on flanks from groin to axilla; elbow and upper arms without dark bars but with distinct coppery orange coloration; fingers and toes with transverse bars. Ventral surface white, with distinct irregular and moderate dark brown spots on chest and belly, and dark marbling on throat; lateral lower lip dark brown scattered with irregular white spots. Supra-axillary gland coppery orange; femoral and pectoral glands white and distinct; ventrolateral glands white, somewhat indistinct from the white venter. Iris not bicolored, uniform dark brown, scattered with minute, coppery reticulations throughout.

Coloration of holotype in preservative. Dorsum dark brown with slightly paler limbs ( Fig. 3 A, B). Ventral surface dull white, with dark brown spots on chest and belly, and marbling on throat. Dorsal color pattern turns to shades of gray and macroglands on the ventral surfaces become less distinct.

Variation. All six paratypes match the overall characters of the holotype (for measurements of the type series see Table 3 ). All type specimens possess a dull white venter scattered with distinct dark blotches and marbling except that the dark patterns on venter is somewhat indistinct in the smallest male paratype, SYS a004597 ( Fig. 6 ). No significant differences between males and females were revealed ( Fig. 5 ), however females are slightly larger than males (SVL 28.8–28.9 mm in females versus 23.8–26.0 mm in males).

Distribution and natural history. Leptolalax tengchongensis sp. nov. is so far only known from its type locality, near Linjiapu substation (a rangers’ station) of the Tengchong Section of Gaoligongshan National Nature Reserve, Tengchong County, Baoshan City, Yunnan Province, China. The new species was found along a clearwater rocky stream (ca. 3–4 m in width and ca. 30 cm in depth) and small nearby seeps in well-preserved montane evergreen broadleaf forest at elevations between 2000–2100 m ( Fig. 7 ); calling males were found mainly hidden under leaf litter, and some were found calling under rocks by the side of the stream.

We conducted three rapid field surveys in the type locality of the new species between April 2014 and July 2015. During the first survey, 28–30 April 2014, very few males of Leptolalax tengchongensis sp. nov. were heard calling and only one male was found and collected, but during the third survey between 15–18 May 2015, calling males of the new species were ubiquitous along the main stream and riparian forest, and five calling adult males and two gravid adult females were collected. No calls and specimens were detected during the second survey on 9– 10 December 2014.

Comparison. By the presence of supra-axillary and ventrolateral glands, Leptolalax tengchongensis sp. nov. can be allocated into the subgenus Lalos Dubois, Grosjean, Ohler, Adler & Zhao, 2010, and distinctly differs from the 14 known species of the subgenus Leptolalax , i.e., L. arayai , L. dringi , L. fritinniens , L. gracilis , L. hamidi , L. heteropus , L. kajangensis , L. kecil , L. marmoratus , L. maurus , L. pictus , L. platycephalus , L. sabahmontanus and L. solus , all of which occur south of the Isthmus of Kra and lack supra-axillary and ventrolateral glands (Dubois et al. 2010; Dehling & Matsui 2013; Matsui et al. 2014b).

Compared to the 30 recognized species in the subgenus Lalos, the relatively small size of Leptolalax tengchongensis sp. nov. (SVL 23.8–26.0 mm in five adult males and 28.8–28.9 mm in two adult females) differs from the larger L. alpinus (females 31.7–32.5 mm), L. botsfordi (males 29.1–32.6 mm, females 30.0–31.8 mm), L. bourreti (males 28.0–36.2 mm, females 42.0–45.0 mm), L. eos (males 33.1–34.7 mm, female 40.7 mm), L. firthi (males 26.4–29.2 mm), L. fuliginosus (males 28.2–30.0 mm), L. lateralis (males 26.9–28.3 mm, female 36.6 mm), L. melanoleucus (males 26.6–28.8 mm, female 32.7 mm), L. minimus (males 25.7–31.4 mm, females 31.6–37.3 mm), L. nahangensis (male 40.8 mm), L. nyx (males 26.7–32.6 mm, females 37.0–41.0 mm), L. oshanensis (males 26.6–30.7 mm, female 31.6 mm), L. pelodytoides (males 27.5–32.3 mm, females 35.5–37.8 mm), L. pyrrhop (males 30.3–33.9 mm, females 30.8–34.3 mm), L. sungi (males 48.3–52.7 mm, females 56.7–58.9 mm), L. tamdil (male 32.3 mm, female 31.8 mm), L. ventripunctatus (females 31.5–35.0 mm), and L. zhangyapingi (males 45.8−52.5 mm), and the smaller L. applebyi (males 19.6–20.8 mm, female 21.7 mm), and L. melicus (males 19.5– 22.7 mm), L. pluvialis (males 21.0–22.0 mm).

In having an iris of uniform coloration, L. tengchongensis sp. nov. differs from L. alpinus , L. bidoupensis , L. eos , L. firthi , L. fuliginosus , L. isos , L. khasiorum , L. melanoleucus , L. minimus , L. pluvialis , L. pyrrhop , L. tamdil , L. ventripunctatus and L. zhangyapingi , all of which have a distinctly bicolored iris.

In having toes with rudimentary webbing and narrow lateral fringes on toes, L. tengchongensis sp. nov. differs from L. applebyi , L. croceus , L. melanoleucus , L. melicus , L. minimus , L. nahangensis , L. nyx , L. oshanensis , L. pluvialis , L. pyrrhop , L. tuberosus and L. ventripunctatus , all of which lack lateral fringes on toes; L. eos , L. khasiorum , L. laui , L. liui and L. zhangyapingi , all of which have wide fringes on toes.

In having a distinct tympanum L. tengchongensis sp. nov. further differs from L. croceus , L. sungi and L. tuberosus , all of which have an indistinct tympanum.

In having distinct large black blotches on flanks, L. tengchongensis sp. nov. differs from L. botsfordi , L. croceus , L. eos , L. firthi and L. isos (without black markings on flanks); and further differs L. aereus , L. alpinus , L. applebyi , L. laui , L. liui , L. pluvialis , L. sungi and L. tamdil , all of which have lesser, smaller and/or indistinct dark spots on flanks.

In having distinct dark brown speckling on the chest and belly, and marbling on the throat, L. tengchongensis sp. nov. differs from L. aereus , L. bourreti , L. eos , L. firthi , L. isos , L. khasiorum , L. laui , L. liui , L. minimus , L. nahangensis , L. nys , L. oshanensis , L. pelodytoides , L. sungi , L. tamdil and L. zhangyapingi , all of which have an immaculate white or pale grey belly; and from L. applebyi (brownish pink ventral surface with white speckling), L. bidoupensis (dark brownish red ventral surface with white speckling), L. botsfordi (dark brownish red ventral surface with white speckling), and L. croceus (bright orange belly in life, fades to cream in preservative).

Figures

FIGURE 3. Holotype of Leptolalax tengchongensis sp. nov. (SYS a 004600) in preservative: (A) dorsal view; (B) ventral view; (C) plantar view of the left foot; (D) volar view of the left hand; (E) lateral view of head. Photos by J. H. Yang.

FIGURE 4. Holotype of Leptolalax tengchongensis sp. nov. (SYS a 004600) in life; inset image illustrates the iris coloration of holotype in life. Photos by J. H. Yang.

FIGURE 5. Leptolalax tengchongensis sp. nov.: (A) A pair in amplexus (male SYS a 004601; female SYS a 004602); (B & C) dorsal and ventral views of male paratype SYS a 004596 in life; (D & E) dorsal and ventral views of female paratype SYS a 004598 in life. Photos by J. H. Yang.

FIGURE 6. Paratypes of Leptolalax tengchongensis sp. nov. in preservative, note the variation in dorsal and ventral patterns: SYS a 004596, SYS a 004597, SYS a 004599, SYS a 004601, SYS a 004598, SYS a 004602 (from left to right). Photos by J. H. Ya ng.

FIGURE 7. Habitat of Leptolalax tengchongensis sp. nov.: (A) microhabitat of calling male holotype SYS a 004600 at type locality, near the rocky main stream; (B) microhabitat of calling males along the seeps at type locality. Photos by J. H. Yang.

Tables

TABLE 3. Measurements (in mm) of type specimens of Leptolalax tengchongensis sp. nov. Abbreviations defined in text.

Sex	SYS a004596 Male	SYS a004597 Male	SYS a004599 Male	SYS a004600 Male	SYS a004601 Male	Mean ± SD (N=5)	SYS a004598 Female	SYS a004602 Female	Mean ± SD (N=2)
SVL HDL HDW	24.9 8.5 8.1	23.9 8.3 7.8	25.6 8.8 8.5	26.0 8.8 8.7	23.8 8.4 8.1	24.84±0.99 8.56±0.23 8.24±0.36	28.9 9.0 9.0	28.8 9.9 9.2	28.85±0.07 9.45±0.64 9.10±0.14
SNT EYE IOD	3.8 3.0 3.0	3.7 3.1 2.9	3.9 3.3 3.1	3.8 3.3 3.2	3.8 3.2 3.0	3.80±0.07 3.18±0.13 3.04±0.11	4.3 3.4 3.2	4.3 3.5 3.3	4.30±0.00 3.45±0.07 3.25±0.07
TMP TEY TIB	1.4 0.7 12.0	1.5 0.8 10.3	1.6 0.8 11.8	1.5 0.9 12.1	1.5 0.8 11.8	1.50±0.07 0.80±0.07 11.60±0.74	1.9 1.1 13.8	1.8 1.1 13.0	1.85±0.07 1.10±0.00 13.40±0.57
ML PL LAHL	5.8 11.0 12.3	5.7 10.4 11.2	6.0 11.7 12.2	6.1 11.9 12.5	6.0 11.4 11.9	5.92±0.16 11.28±0.60 12.02±0.51	7.1 12.4 14.3	7.0 12.8 13.8	7.05±0.07 12.60±0.28 14.05±0.35
HLL HDL/HDW HDL/SVL	37.9 1.05 0.34	34.9 1.06 0.35	39.1 1.04 0.34	39.7 1.01 0.34	39.1 1.04 0.35	38.14±1.93 1.04±0.02 0.34±0.01	46.2 1.00 0.31	44.8 1.08 0.34	45.50±0.99 1.04±0.05 0.33±0.02
SNT/HDL SNT/ED EYE/TMP	0.45 1.27 2.14	0.45 1.19 2.07	0.44 1.18 2.06	0.43 1.15 2.20	0.45 1.19 2.13	0.44±0.01 1.20±0.04 2.12±0.06	0.48 1.26 1.79	0.43 1.23 1.94	0.46±0.03 1.25±0.03 1.87±0.--11
TMP/EYE TEY/TMP TIB/SVL	0.47 0.50 0.48	0.48 0.53 0.43	0.48 0.50 0.46	0.45 0.60 0.47	0.47 0.53 0.50	0.47±0.01 0.53±0.04 0.47±0.02	0.56 0.58 0.48	0.51 0.61 0.45	0.54±0.03 0.60±0.02 0.46±0.02
LAHL/SVL HLL/SVL TIB/HLL	0.49 1.52 0.32	0.47 1.46 0.30	0.48 1.53 0.30	0.48 1.53 0.30	0.50 1.64 0.30	0.48±0.01 1.54±0.07 0.30±0.01	0.49 1.60 0.30	0.48 1.56 0.29	0.49±0.01 1.58±0.03 0.29±0.01