Achalinus pingbianensis, Li & Yu & Wu & Liao & Tang & Liu & Guo, 2020

Li, Ke, Yu, Min, Wu, Ya-Yong, Liao, Lin-Hong, Tang, Kui, Liu, Qin & Guo, Peng, 2020, A new species of the genus Achalinus (Squamata: Xenodermatidae) from southeastern Yunnan Province, China, Zootaxa 4860 (1), pp. 116-128 : 121-123

Achalinus pingbianensis sp. nov.

( Figures 1 , 3–5 )

Holotype. YBU 18273, an adult male, collected by K. Li, M. Yu, L. H. Liao, and K. Tang at night on July 12, 2019 in Dawei Mountain Nature Reserve , Pingbian County (N 103°42′01.02″, E 22°55′02.78″), southeastern Yunnan Province, China, at an elevation of 1, 968 m above sea level.

Diagnosis. A new species of Achalinus having the combination of (1) dorsal scales strongly keeled, 23 rows throughout; (2) tail relatively short, TaL/TL 24.3%; (3) length of suture between internasals subequal to that between prefrontals; (4) nasal divided into two sections by nasal cleft; (5) loreal fused with prefrontal, with the prefrontal extending towards the supralabials; (6) supralabials 7, the fifth and sixth widely in contact with eye; (7) infralabials 6, the first three touching the first pair of chin shields; (8) temporals 2+2+3 on right side and 2+2 on left side, the uppermost anterior temporal in contact with eye; (9) ventrals 164+2, subcaudals 56, arranged in single row; (10) anal entire; (11) uniform black, tinged weakly iridescent; (12) light black beneath.

Description of holotype. An adult male with a total length of 429 mm (SVL 345 mm and TaL 84 mm), TaL/TL 24.3%. Body slender, cylindrical; head slightly distinct from neck; eye small, with vertically oval pupil; rostral small, triangular, slightly visible from above. LSBI subequal to LSBP. Nostril in the anterior part of the nasal, posterior margin of nostril with a distinct nostril cleft, the posterior section of nasal vertically rectangular. Frontal pentagonal, slightly broader than long, pointed backwards, much shorter than the parietals; each parietal bordered by an elongated nuchal. Nuchals separated from each other behind parietals by one small scale; the second pair of nuchals about 2/3 the size as the first pair. Loreal lacking, prefrontals stretch towards the SPL. Preocular and postocular absent. A single SPO. Two aTMP, elongated, upper one smaller, only uppermost in contact with eye, four elongated pTMP on right side, and pTMP of the left side nondescript. SPL 7, the first smallest, fifth and sixth in contact with the eye, seventh longest. One mental, followed by six IFL, the first pair of IFL in contact with each other; the first three IFL touching the first pair of chin shields; posterior pair of chin shields larger, length of the suture between the first pair equal to that between the second pair, laterally in contact with third to fifth IFL. Dorsal scales lanceolate and strongly keeled, in 23-23-23 rows, those of the most outer rows on both sides significantly enlarged and smooth. VS 164 (plus two preventrals), distinctly rounded laterally; SC 56, not paired; anal entire. Coloration of holotype in life. Uniform black above, vertebral line unseen. All scales tinged iridescent and margin of scales greyish white. Uniform light black beneath. The ventral tail dark brown, the dorsal tail surface iridescent black ( Figs. 3 and 4 ). Coloration of holotype in preservation. All scales tinged weakly iridescent. Uniform black, margin of all scales dark grey.

Etymology. The specific name refers to the type locality of this species, Dawei Mountain Nature Reserve, Pingbian County, Southeastern Yunnan, China. We suggest the common names as Ping Bian Ji She (DZṈṘẘ) in Chinese and Pingbian odd-scaled snake in English.

Distribution and habits. Currently, Achalinus pingbianensis sp. nov. is known only from its type locality at Dawei Mountain Nature Reserve, Pingbian County, southeastern Yunnan Province, China ( Fig. 1 ). The specimen was found at 9:00 PM on the road with moss and leaf litters in well-preserved montane evergreen broadleaf forest on both sides. Comparisons. Achalinus pingbianensis sp. nov. differs from all other species of Achalinus , except A. jinggangensis and A. timi , by the absence of a loreal. Achalinus pingbianensis sp. nov. further differs from A. jinggangensis , A. timi , A. ater , A. hainanus , A. rufescens , A. emilyae , A. yunkaiensis , and A. juliani by having length of suture between internasals subequal to that between prefrontals (vs. distinctly longer than that between prefrontals). Achalinus pingbianensis sp. nov. can be easily distinguished from A. formosanus (mDSR 25–27), A. meiguensis (mDSR 19–21), A. timi (mDSR 25), and A. niger (mDSR 27) by having mDSR 23, and from A. hainanus and A. meiguensis by the presence of internasals. In addition, the new species can be differentiated from some congeners in VS, SC, and Tal/TL ratio. Comparisons between the new species and its congeners are summarized in Table 4 .

......continued on the next page

Figures

FIGURE 1. Map showing the type localities of Achalinus pingbianensis sp. nov. (1= Pingbian County, Southeastern Yunnan Province, China), of Achalinus ater (2 = Tam Dao, Thái Nguyên Province, Vietnam), of Achalinus juliani (3 = Nguyen Binh, Cao Bang Province, Vietnam), and of Achalinus timi (4 = Copia Nature Reserve, Son La Province, Vietnam).

FIGURE 3. General view of the holotype of Achalinus pingbianensis sp. nov. in life (Photography by K. Li).

FIGURE 4. The holotype of Achalinus pingbianensis sp. nov. in preservative in dorsal (A), ventral (B), right lateral (C) and left lateral (D) views of head and lateral view of mid-body.

FIGURE 5. Habitat of Achalinus pingbianensis sp. nov. in Dawei Mountain Nature Reserve, Pingbian County, Southeast Yunnan Province, China (Photography by M. Yu).