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| Achalinus ningshanensis occidentalis Xu, Ma, Cai, Yang, Zhang,Gu, Zhu, Huang & Peng, 2024 |
Simple Summary: The odd-scaled snake genus Achalinus Peters, 1869 is widely distributed in northern Vietnam, China, and Japan, but is a group of snakes about which there is meager information. Achalinu ningshanensis was first described in 2022 and is only known from Ningshan County, Shaanxi Province, China. However, we detected a clear contradiction in the phylogenetic position between the type series and our newly collected topotypes. To solve this, we combined a mitochondrial phylogenetic analysis and morphological comparisons to revise the taxonomic status of A. ningshanensis in this study. Based on four mitochondrial combined gene fragments, molecular phylogenetic analyses indicated that A. ningshanensis is nested within a highly supported monophyletic group, forming a sister taxon to A. spinalis, which also revealed two well-supported lineages of A. ningshanensis. Based on morphology and phylogenetic methods, the lineage composed of the population from western Sichuan and southwestern Shaanxi represents a new subspecies, Achalinus ningshanensis occidentalis ssp. nov., and the other lineage represents the original species from southern Shaanxi and northeastern Sichuan, which we allocated as Achalinus ningshanensis ningshanensis. Finally, we provide a further discussion of the phylogenetic and taxonomic issues among the genus Achalinus.
Abstract
Achalinu ningshanensis (Yang, Huang, Jiang, Burbrink, and Huang, 2022) was first described in Ningshan County, Shaanxi Province, China in 2022, based on seven female specimens. In this study, based on phylogenetic analyses using mitochondrial 12S ribosomal RNA (12S), 16S ribosomal RNA (16S), cytochrome c oxidase subunit 1 (CO1), cytochrome b (cyt b) gene fragments, and morphological examinations of specimens, we revise the taxonomic status of A. ningshanensis, and provide additional data on this species. The molecular phylogeny indicated that A. ningshanensis is nested in a highly supported monophyletic group, forming a sister taxon to A. spinalis, and is divided into two well-supported lineages, A and B, with an uncorrected p-distance between lineages from 3.6 to 4.3% for CO1. Therefore, we proposed that Lineage B from western Sichuan and southwestern Shaanxi is a new subspecies, Achalinus ningshanensis occidentalis ssp. nov., and Lineage A from southern Shaanxi and northeastern Sichuan is allocated as Achalinus ningshanensis ningshanensis. Morphologically, the new subspecies can be distinguished from its congeners, especially from Achalinus ningshanensis ningshanensis, by the following characteristics: (1) the tail is relatively short, with a TAL/TL ratio of 0.202–0.226 in males, and 0.155–0.178 in females; (2) there are two pairs of chin-shields; (3) there are 21–22 maxillary teeth; (4) the length of the suture between internasals is significantly shorter than that between prefrontals, with an LSBI/LSBP ratio of 0.502–0.773; (5) there are six supralabials, with the fourth and fifth in contact with the eye; (6) there are five to six infralabials, and the first to third or fourth touches the first pair of chin-shields; (7) there is one hexagonal loreal, with an LorH/LorL ratio of 0.612–1.040; (8) the two anterior temporals are in contact with the eye; (9) there are 155–160 ventrals in males, and 165–174 in females; (10) there are 60–65 subcaudals in males, and 49–53 in females, which are not paired; and (11) the dorsum is iridescent and uniformly charcoal black, lacks a longitudinal vertebral line, and has a dark brown or dark gray ventral area.
Keywords: Achalinus ningshanensis occidentalis ssp. nov.; Achalinus ningshanensis ningshanensis; mitochondrial DNA; morphological characters; taxonomy; molecular phylogeny
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| Preserved specimen of the holotype of Achalinus ningshanensis ningshanensis (ANU 20220001, female). Photos by Diancheng Yang and Yuhao Xu. Scale bars: 10 mm. |
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| Dorsal (A) and ventral (B) views of living Achalinus ningshanensis ningshanensis. (A1,B1): QHU 2024017, male, from Ningshan County, Shaanxi Province; (A2,B2): QHU 2023009, female, from Ningshan County, Shaanxi Province. Photos by Yuhao Xu. Scale bars are not shown. |
Achalinus ningshanensis ningshanensis Yang, Huang, Jiang, Burbrink and Huang, 2022
Ningshan odd-scaled Snake
Níng Shǎn Jǐ Shé Zhǐ Míng Yà Zhǒng (宁陕脊蛇指名亚种)
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| Dorsal (A) and ventral (B) views of Achalinus ningshanensis occidentalis ssp. nov. in life. (A1,B1): QHU 2023013, holotype, adult female, from Longquanyi District, Sichuan Province; (A2,B2): QHU 2023014, paratype, adult male, from Longquanyi District, Sichuan Province; (A3,B3): QHU 2024016, paratype, adult male, from Hongya County, Sichuan Province. Photos by Yuhao Xu. |
Yuhao Xu, Shun Ma, Bo Cai, Diancheng Yang, Tianyou Zhang,Tianxuan Gu,Fengcheng Zhu,Song Huang and Lifang Peng. 2024. Taxonomic Revision of Ningshan Odd-Scaled Snake, Achalinus ningshanensis (Serpentes, Xenodermidae), with Description of a New Subspecies from Western China. Animals. 14(23); 3425. DOI: doi.org/10.3390/ani14233425
Yang, D.C.; Huang, R.Y.; Jiang, K.; Burbrink, F.T.; Gong, Y.A.; Yu, J.; Zhang, Y.; Huang, T.Q.; Huang, S. 2022. A New Species of the Genus Achalinus (Squamata: Xenodermidae) from Ningshan County, Shaanxi Province, China. Zootaxa.5190(1); 127–140. DOI: doi.org/10.11646/zootaxa.5190.1.5
