Achalinus yunkaiensis J. Wang, Y. Li & Y.Y. Wang, 2019

Wang, Jian, Li, Yao, Zeng, Zhao-Chi, Lyu, Zhi-Tong, Sung, Yik-Hei, Li, You-Yu, Lin, Chao-Yu & Wang, Ying-Yong, 2019, A new species of the genus Achalinus from southwestern Guangdong Province, China (Squamata: Xenodermatidae), Zootaxa 4674 (4), pp. 471-481 : 474-479

Achalinus yunkaiensis J. Wang, Y. Li & Y.Y. Wang , sp. nov.

Figure 2 & 3A, B

Holotype. SYS r001903 ( Figure 2 ), adult male, collected by Jian Wang and Honghui Chen on 10 April 2018 from Dawuling Forestry Station (22.27580°N, 111.19524°E; 1,500 m a.s.l.), Maoming City, Guangdong Province, China.

Paratypes. Adult male, SYS r001443 ( Figure 3 , A 1−A 3 ), collected by Jian Wang and Zhao-Chi Zeng on 16 April 2016; juvenile males, SYS r001502, 1503 ( Figure 3 , B 1−B 3 ), collected by Jian Wang, Can-Rong Lin, Zhao- Chi Zeng and Chun-Peng Guo on 27 June 2016; and a single adult female, SYS r001902, collected by Jian Wang and Hong-Hui Chen on 10 April 2018; all from the same locality as the holotype.

Diagnosis. (1) dorsal scales strongly keeled, in 23 rows throughout the body, the most outer rows on both sides smooth and significantly enlarged; (2) tail relatively shorter, TaL/TL ratio 18.5–20.0%; (3) maxillary teeth 20–22; (4) length of suture between internasals subequal to that between the prefrontals; (5) nasal divided into two sections by nasal cleft, posterior one nearly half as long as anterior, LaSN/LpSN 0.4–0.5; (6) loreal elongated, nearly twice as wide as high, HiL/LeL 0.5–0.6; (7) supralabials six, the fourth and fifth ones widely in contact with eye; (8) infralabials six, the first three (rarely the first four) in contact with the first pair of chin shields; (9) temporals 2+2+3 (rarely 2+2+4), the two anterior temporals in contact with eye; (10) ventrals 151–162, subcaudals 49–56 arranged in single row, not paired; (11) cloacal entire; (12) uniform brown (in adults) or black (in juveniles) above, tinged weakly iridescent, with a longitudinal dark-colored vertebral line; (13) light brown (in adults) or greyish white (in juveniles) beneath; and (14) dorsum with a longitudinal dark brown vertebral stripe from posterior margin of parietals to tail tip.

Comparisons. Coloration of adults of Achalinus yunkaiensis sp. nov. is most similar to that of A. rufescens ( Figure 3 ), and the new species can be distinguished from the examined specimens of A. rufescens by less maxillary teeth, MT 20–22 (vs. 23–25 in A. rufescens ), more ventrals in a single female, V 156 (vs. V 132–140 in females of A. rufescens ), more infralabials, IFL 6 (vs. IFL 5 in A. rufescens ), length of suture between internasals subequal to that between the prefrontals (vs. distinctly longer than that between prefrontals in A. rufescens ), nasal section behind nasal cleft nearly half as long as those before nasal cleft, LaSN/LpSN 0.4–0.5 (vs. nearly subequal in A. rufescens , LaSN/LpSN 0.9–1.2); loreal nearly twice as wide as high, HiL/LeL 0.5–0.6 (vs. nearly subequal in A. rufescens , HiL/LeL 0.8–1.0), moreover, the new species can be distinguished from the holotype of A. rufescens by SPL 6, the 4 th– 5 th in contact with eye (vs. SPL 5, the 3 rd– 4 th in contact with eye), IFL 6 (vs. IFL 5), both of the two anterior temporals in contact with eye (vs. only the upper on in contact with eye), V 151–162 (vs. V136), SC 56–59 (vs. SC 82); details see Table 4.

Coloration of juveniles of Achalinus yunkaiensis sp. nov. is most similar to that of A. spinalis and A. ater , and the new species can be distinguished by the coloration of adult individuals, dorsum brown (vs. dorsum black in A. spinalis and A. ater ) ( Figure 3 ); venter light brown in adults and greyish white in juveniles (vs. venter black brown in A. spinalis and A. ater ); presence of a longitudinal mid-dorsal stripe (vs. absence in A. spinalis and A. ater ); length of suture between internasals subequal to that between the prefrontals (vs. shorter in A. spinalis and A. ater ).

In having 23 mid-dorsal scale rows and presence of internasals, Achalinus yunkaiensis sp. nov. can be easily distinguished by A. fomosanus (mid-dorsal scale rows 27, lacking internasals), A. hainanus (lacking internasals), A. meiguensis (mid-dorsal scale rows 19–21, lacking internasals), and A. niger (mid-dorsal scale rows 27). A. yunkaiensis sp. nov. further differs from A. jinggangensis by having a single loreal, length of suture between internasals equal to that between the prefrontals (vs. loreal absent, length of suture between internasals distinctly longer than that between prefrontals in A. jinggangensis ).

Achalinus yunkaiensis sp. nov. can be easily distinguished from A. emilyae , A. juliani and A. timi , which are currently recorded from northern Vietnam, as followed: having 23 mid-dorsal scale rows (vs. mid-dorsal scale rows 25 in A. timi ); presence of a single loreal (vs. loreal absent in A. timi ); length of suture between internasals equal to that between the prefrontals (vs. length of suture between internasals distinctly longer than that between prefrontals in A. emilyae , A. juliani and A. timi ); less maxillary teeth, MT 20–22 (vs. MT 27–28 in A. emilyae , MT 28 in A. juliani , and MT 27 in A. timi ); infralabials six (vs. IFL 5 in A. emilyae ).

Achalinus yunkaiensis sp. nov. differs from A. werneri by the relatively shorter tail length, TaL/TL ratio 18.5– 20.0% (vs. TaL/TL ratio 25.0–30.0% in A. werneri ); temporals 2+2+3 (seldom 2+2+4) (vs. temporals 2+ 2 in A. werneri ); subcaudals 49–56 (vs. subcaudals 67–98 in A. werneri ).

Description of holotype. An adult male with a total length of 343 mm (SVL 279.7 mm and TaL 63.3 mm); tail relatively shorter, TaL/TL ratio 18.5%; body slender, cylindrical; head slightly distinct from neck; eye small, with vertically oval pupil; left maxillary teeth 22, equally sized and curved; rostral small, triangular, slightly visible from above; length of the suture between the internasals subequal to that between the prefrontals; nostril in the anterior part of the nasal, posterior margin of nostril with a distinct nostril cleft, the posterior section of nasal vertically rectangular, posterior section nearly half as long as the anterior part, LaSN/LpSN 0.4; a single pentagonal frontal, 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 two small scales; second pair of nuchals about half the size of first pair; a single loreal, distinctly wider than high, extending from the nasal to the eye, HiL/LeL 0.6; a single supraocular, elongate, two times wider than high; two anterior temporals, elongated, upper one smaller, wide in contact with eye, the lower one narrowly in contact with eye; two elongated middle temporals, the upper much larger, the lower one in contact with the sixth supralabial; three elongate posterior temporals, the most upper one the largest; supralabials six, the first smallest, fourth and fifth widely in contact with the eye, sixth longest; third and fourth in broad contact with the loreal; one mental, followed by six infralabials; first pair of infralabials in contact with each other behind the mental; first three infralabials on left and first four on right in contact with the first pair of chin shields; posterior pair of chin shields smaller, length of the suture between the first pair equal to that between the second pair, laterally in broad contact with the fourth infralabial on left, in broad contact with the fourth infralabial, and in narrow contact with the fifth infralabial on right.

Dorsal scales lanceolate and strongly keeled; dorsal in 23–23–23 scale rows, those of the most outer rows on both sides significantly enlarged and smooth; ventrals 151 (plus one preventral), distinctly rounded laterally; subcaudals 49, not paired; cloacal entire.

Coloration of holotype in life. All scales tinged weakly iridescent. Dorsum brown, the most inner three rows of dorsal scale dark brown, forming a longitudinal vertebral line which starts from posterior margin of the parietals to tail tip. Margin of all scales greyish white. Coloration of supralabials and temporal region much lighter. Iris dark brown, pupil black. Venter light brown, coloration much lighter than that of supralabials and temporal region; ventral tail dark brown. The first pair of chin shields brown mottling with greyish white patches, the second pair greyish white with brown patches on sides. Ventral scales light brown with brown patches on both sides.

Coloration of holotype in preservative. All scales tinged weakly iridescent. Coloration darkens from dorsum to venter, dorsum dark grey, longitudinal vertebral line black. Margin of all scales dark grey. Coloration of venter is fading, grey brown; ventral tail dark grey brown.

Variations. Measurements, body proportions, teeth counts and scale counts were listed in Table 3 .All paratypes are morphologically very similar to the holotype except that: (1) the adult male SYS r001443 possessed significantly larger body size, TL 417.6 mm, even with a broken tail (vs. TL 343 mm in the male holotype); (2) higher maxillary teeth counts in all paratypes, MT 21–22 (vs. MT 20 in the holotype); (3) the first four infralabials in contact with the first pair of chin shields on the right side in SYS r001902 (vs. the first three in contact with the first pair of chin shields on the other side of SYS r001902, in paratypes SYS r001443, 1502, 1503, and the holotype); (4) temporals 2+2+4 on the right side in SYS r001443 (vs. temporals 2+2+3 on the other side of SYS r001443, in paratypes SYS r001503, 1503, 1902, and the holotype); and (5) dorsum black and venter greyish white, both sides of each central scale black in both juvenile individuals SYS r001502, 1503 (vs. dorsum brown and venter light brown, both sides of each central scale brown in all three adult individuals SYS r001443, 1902, 1903) ( Figure 3 ) .

Etymology. The specific epithet, yunkaiensis , is in reference to the type locality, Dawuling Forestry Station and adjacent Xianrendong Scenic Area in Guangdong Province, China located in the Yunkai Mountains. For the common name, we suggest “Yunkai Mountain’s Odd-scaled Snake” or “Yunkai Mountain’s Burrowing Snake”, and Chinese name “Yun Kai Ji She (KHṞḡ)”.

Distribution and habits. Currently, Achalinus yunkaiensis sp. nov. is only known from its type locality Dawuling Forestry Station in Maoming City and adjacent Xianrendong Scenic Area in Gaozhou City of Guangdong Province ( Figure 4 ). The new species was found on leaf litters in well-preserved montane evergreen broadleaf forest (900–1,600 m a.s.l.).

Figures

FIGURE 1. Bayesian inference and maximum-likelihood phylogenies. Numbers before slashes indicate Bayesian posterior probabilities (>0.50 retained) and numbers after slashes are bootstrap support for maximum likelihood (1000 replicates) analyses (>50 retained). The symbol “-” represents bootstrap value below 50%.

FIGURE 2. General aspect in life of the adult male holotype of Achalinus yunkaiensis sp. nov., SYS r001903.

FIGURE 3. Coloration and head scalation differences among: A. adult Achalinus yunkaiensis sp. nov., SYS r001443; B. juvenile A. yunkaiensis sp. nov., SYS r001503; C. A. rufescens, SYS r001689 from Shimentai Nature Reserve, Guangdong Province; D. A. spinalis, SYS r001327 from Mt. Badagong, Sangzhi, Hunan Province.

FIGURE 4. Map showing the type locality of Achalinus yunkaiensis sp. nov., Dawuling Forestry Station and adjacent Xianrendong Scenic Area in southwestern Guangdong Province, China.

Tables

TABLE 3. Measurements, scale counts and body proportions of Achalinus yunkaiensis sp. nov..

Voucher	SYS r 001443	SYS r 001502	SYS r 1503	SYS r 001903	SYS r 001902
Sex	♂	♂juv.	♂juv.	♂	♀
TL	417.6	258.4	232	343	448.1
SVL	358.5	206.8	43.3	279.7	386.3
TaL	59.1	51.6	188.7	63.3	61.8 (broken)
TaL/TL	broken tail	20.0%	18.7%	18.5%	broken tail
MT	21	21	21	20	22
SPL	6	6	6	6	6
SPL-Loreal	3rd–4th	3rd–4th	3rd–4th	3rd–4th	3rd–4th
IFL	6	6	6	6	6
IFL-1 st chin	1st–3rd	1st–3rd	1st–3rd	1st–3rd	1st–3rd/1 st–4th
Loreal	1	1	1	1	1
HiL	1.3	0.9	0.8	1.0	1.2
LeL	2.2	1.4	1.3	1.8	2.2
HiL/LeL	0.6	0.6	0.6	0.6	0.5
LaSN	0.6	0.3	0.3	0.5	0.6
LpSN	1.4	0.8	0.7	1.0	1.2
LaSN/ LpSN	0.4	0.4	0.4	0.5	0.5
SpO	1	1	1	1	1
TMP	2+2+3/2+2+4	2+2+3/2+2+3	2+2+3/2+2+3	2+2+3/2+2+3	2+2+3/2+2+3
Elongate aTMP	2nd	2nd	2nd	2nd	2nd
Elongate mTMP	1st	1st	1st	1st	1st
Elongate pTMP	1st	1st	1st	1st	1st
DSR	23–23–23	23–23–23	23–23–23	23–23–23	23–23–23
V	155	151	162	151	156
SC	42 (broken)	56	50	49	38 (broken)