Thursday, May 25, 2023

[Herpetology • 2023] Achalinus dabieshanensis • A New Species of the Genus Achalinus (Serpentes: Xenodermidae) from the Dabie Mountains, Anhui, China


Achalinus dabieshanensis Zhang, Liu, Huang and Zhang 

in Zhang, Liu, Huang, Hu, Yu, Sun, Zhang, Wen et Zhang, 2023. 
 大别山脊蛇  || DOI: 10.3390/ani13040708 

Abstract
A new species of Xenodermid snake, Achalinus dabieshanensis sp. nov., was described based on three specimens (two female and one male) collected from the Dabie Mountains of western Anhui Province. It can be distinguished from known congeners by a significant genetic divergence in the mitochondrial gene fragment COI (p-distance ≥ 9.4%) and the following combination of characteristics: (1) length of the suture between the internasals being distinctly shorter than between the prefrontals; (2) a single loreal; (3) dorsal scales strongly keeled, in 23 rows throughout the body; (4) two pairs of prefrontals; (5) six supralabials; (6) five infralabials; (7) temporals 2 + 2 + 3 (or 2 + 2 + 4); (8) 141–155 ventrals; (9) 45–55 subcaudals, unpaired; (10) anal entire; (11) weakly iridescent tinged, uniform, brown to black dorsum with vertebral scales and about three adjacent dorsal scales dark brown forming a longitudinal vertebral line from posterior margin of parietals to tail tip; (12) light brown venter, ventral shields wide, visible on both sides, light brown flanks, giving the appearance of a black subcaudal streak. The recognition of the new species increases the number of described Achalinus species to 22.

Keywords: Achalinus dabieshanensis sp. nov.; morphology; phylogenetics; taxonomy

  The general aspect of the adult female holotype (AHU 2018-EE-0710) and the adult male paratype (AHU 2016-EE-0615) of Achalinus dabieshanensis sp. nov.
(A–D) the holotype left and right and dorsal and ventral view of head (showing length of the suture between internasals shorter than it between prefrontals, a single loreal, six supralabials, five infralabials and temporals 2 + 2 + 3);
(E–H) the paratype left and right and dorsal and ventral view of head;
(I) Overall view of the preserved holotype; (J) the holotype dorsal view of midbody (showing dorsum iridescent brown with three scales wide dorsal black line).
Photos by Lihua Huang and Caiwen Zhang.

Achalinus dabieshanensis sp. nov. Zhang, Liu, Huang and Zhang 

Diagnosis: A new species of Achalinus with: (1) weakly iridescent tinged, uniform brown dorsum with vertebral scales and about three adjacent dorsal scales dark brown, forming longitudinal vertebral line from posterior margin of parietals to tail tip; (2) light brown venter; (3) relatively short tail, TaL/TL ratio 16.8–22.3%; (4) suture length between internasals distinctly shorter than between prefrontals; (5) one loreal (height/length ratio 0.79–0.89); (6) six supralabials, 4th and 5th widely in contact with eye; (7) temporals 2 + 2 + 3 (or 2 + 2 + 4), two elongated anterior temporals in contact with eye; (8) five infralabials, two pairs of chin shields, first three infralabials touching first pair of chin shields; (9) 141–155 ventrals, 45–55 subcaudals, not paired; (10) dorsal scales in 23 rows throughout, strongly keeled, but outermost rows on both sides smooth and significantly enlarged; (11) anal entire.

Etymology: The specific epithet, Achalinus dabieshanensis sp. nov., refers to the distribution of the new species in the Dabie Mountains in Anhui, China. We suggest the English name would be the “Dabie Mountains Odd-scaled Snake” or “Dabie Mountain Burrowing Snake” and the Chinese name “大别山脊蛇 (Dà Bié Shān Jǐ Shé)”.

 General view of the holotype of Achalinus dabieshanensis sp. nov. in life
(Photography by Kai Zhao).

 Conclusions: 
A new species of Achalinus, Achalinus dabieshanensis sp. nov., is described based on three specimens collected from the Dabie Mountains of western Anhui Province. It appears to be widespread in the Dabie Mountains. The discovery of new species made the members of the genus Achalinus distribution area extend northward to the Dabie Mountain in the lower reaches of the Yangtze River. However, their discovery is largely accidental, which makes it difficult for us to make accurate judgments on the abundance and population status of this new species in the Dabie Mountains. Further investigations will be necessary to assess the risk of extinction of this species.


 Caiwen Zhang, Kai Liu, Ruyi Huang, Tingli Hu, Lei Yu, Ruolei Sun, Yucai Zhang, Jing Wen and Baowei Zhang. 2023. A New Species of the Genus Achalinus (Squamata: Xenodermidae) from the Dabie Mountains, Anhui, China. Animals 2023, 13(4), 708. DOI: 10.3390/ani13040708 
 
Simple Summary: A new species of odd-scaled snake in the genus Achalinus is described from Dabie Mountains Luan City, Anhui Province, China, based on one male and two female specimens. Bayesian inference and maximum likelihood analyses based on a mitochondrial DNA fragment (CO1) indicated the new taxon is different from its congeners (p–distance ≥ 9.4%). Morphologically, the new species can be diagnosed from the other species by a combination of 12 characters. The recognition of the new species brings the number of described Achalinus species to 22.