Tuesday, November 28, 2017

[Herpetology • 2017] Opisthotropis zhaoermii • A New Species of the Southeast Asian Genus Opisthotropis (Serpentes: Colubridae: Natricinae) from western Hunan, China

Opisthotropis zhaoermii 
Ren, Wang, Jiang, Guo & Li, 2017

 Zhao’s Mountain Stream Snake, 赵氏后棱蛇  || DOI: 10.24272/j.issn.2095-8137.2017.068  

A new species of natricine snake of the Southeast Asian genus Opisthotropis Gü nther, 1872 is described from western Hunan Province of China based on both mitochondrial DNA and morphological data. The new species is morphologically most similar and genetically most closely related to O. cheni Zhao, 1999 and O. latouchii (Boulenger, 1899), but possesses considerable genetic divergence (p-distance 5.1%-16.7%) and can be differentiated from all other congeners by a combination of the following morphological characters: (1) body size large (total length 514-586 mm) and strongly built; (2) dorsal scale rows 17 throughout, feebly keeled anteriorly and moderately keeled posteriorly; (3) ventral scales 147-152, subcaudal scales 54-62; (4) preocular absent, loreal elongated and touching orbit; (5) supralabials 8-9, fifth and sixth entering obit; (6) anterior temporals short, length 1.74-2.04 times longer than width; (7) maxillary teeth subequal, 28-30; (8) dorsal surface of head with distinct irregular yellow stripes and markings edged with ochre; (9) body with clear black and yellow longitudinal streaks, partly fused to several lighter patches or thicker stripes anteriorly; and (10) venter pale yellow, with asymmetric blackish speckles along outer margin. We present an updated diagnostic key to all members of the genus Opisthotropis, and recommendations on the ecological study for the group are provided.

Key words: Distribution, Natricinae, Natural history, Taxonomy, OpisthotropisOpisthotropis zhaoermii sp. nov.

Figure 1: General and close-up views of Opisthotropis zhaoermii sp. nov. in life
holotype CIB109999 (adult female), A: General view; B: Close-up view;
 and paratype CIB109998 (adult male), C: General view; D: Close-up view.

Photos by Jin-Long Ren
 DOI: 10.24272/j.issn.2095-8137.2017.068 

Distribution and natural history: This species is only known from the type locality presently (Figure 6). Opisthotropis zhaoermii sp. nov. inhabits small, fast-flowing mountain streams in forested areas, with water temperature and pH between 19.9–21.2 °C and 7.85–7.93, respectively. Being nocturnal, individuals were seen swimming at the edge of the backwater of travertine waterfalls from 2100h to 0100h at night (Figure 7). The holotype was collected during a heavy rainstorm that caused the water to become extreme turbid, with water temperature and pH measurements of 19.5 °C and 8.13, respectively. 
When handled, individuals never stroked or displayed threating postures. Instead, individuals struggled violently and released a musky, pungent, and enduring defensive odor, much like that of O. balteata and O. kuatunensis (Pope, 1935). The scales of the snakes become dehydrated and crimped quickly after leaving the water for about 10 min, but recovered rapidly when returned to water. Similar to other congeners in China, the new species may prey on earthworms, tadpoles, freshwater isopods, crabs, and small fish (Pope, 1935). Other herpetofauna, including Quasipaa boulengeri, Odorrana schmackeri, Lycodon rufozonatum, L. fasciatus, and Deinagkistrodon acutus, were observed sympatric with the new species. 

Etymology: The specific epithet, zhaoermii, is derived from the name of an internationally renowned Chinese herpetologist, Prof. Er-Mi Zhao, who unfortunately passed away on 24 December 2016. Designation of this specific epithet honors his great contribution to herpetological research in China, specifically to his contribution to the taxonomy of Opisthotropis, including the first description of the sister species (i.e., O. cheni, see above) of the newly found species. We suggest Zhao’s Mountain Stream Snake as its English common name, and “Zhao Shi Hou Leng She” (赵氏后棱蛇) as its Chinese common name. 

Jin-Long Ren, Kai Wang, Ke Jiang, Peng Guo and Jia-Tang Li. 2017. A New Species of the Southeast Asian Genus Opisthotropis (Serpentes: Colubridae: Natricinae) from western Hunan, China.    Zoological Research. 38(5); 251-263. DOI: 10.24272/j.issn.2095-8137.2017.068      

文章导读: 摘要 后棱蛇属 Opisthotropis Günther,1872物种分布于中国南部和东南亚的广泛区域。基于线粒体DNA与形态学证据,描述了后棱蛇属 Opisthotropis一新种赵氏后棱蛇Opisthotropis zhaoermii sp.nov.,该物种目前仅知于模式产地湖南古丈县。该新种在遗传与形态上与莽山后棱蛇 O. cheni Zhao,1999和山溪后棱蛇 O. latouchii(Boulenger,1899)最为接近,但遗传距离与本属其他物种差异较大(5.1%-16.7%),并可根据以下形态学特征与本属其他物种进行区分:(1)体型较大(体全长514-586 mm)而粗壮;(2)通身背鳞17行,前部起弱棱而后增强;(3)腹鳞147-152枚,尾下鳞54-62枚;(4)无眶前鳞,颊鳞延长而入眶;(5)上唇鳞8-9,第五枚与第六枚入眶;(6)前颞鳞短,长宽比1.74-2.04;(7)上颌齿等大,28-30枚;(8)头背有边缘赭色的不规则黄色线纹;(9)身体有黑黄相间的纵纹,体前部的部分纵纹合并成数个浅色斑块或条纹;(10)腹部浅黄色,外侧有不对称点斑。此外,本研究更新了后棱蛇属所有物种的检索表,对该类群的生态学研究提出了建议。

关键词: 分布,  分类,  后棱蛇属 Opisthotropis,  生活史,  水游蛇亚科,  赵氏后棱蛇 Opisthotropis zhaoermii sp.nov.    


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