Achalinus

Abstract: A new species of the xenodermatid snake genus Achalinus Peters, 1869 is described from Yunnan Province, Southwest China, based on a single male specimen. The new species is assigned to the genus Achalinus on the basis of absence of preocular and postocular, subcaudals arranged in single row, and results of phylogenetic analyses of mitochondrial DNA CO1 sequence data. Achalinus pingbianensis sp. nov. differs from its congeners by the combination of following morphological characters: absence of a loreal, internasals subequal to that between prefrontals and dorsal scales strongly keeled, 23 rows throughout. Currently, 13 species are in the genus Achalinus, further taxonomical and phylogenetic studies based on more extensive samples and more markers will help understand the cryptic diversity and clarify their interspecific relationships.

Abstract: Achalinus, commonly known as odd-scaled snakes due to their unique scutellation, are a fascinating group of xenodermid snakes distributed throughout east Asia. Currently, northern Vietnam is known to host six species of Achalinus, three of which are considered endemic. During recent herpetofaunal surveys conducted in the Bac Me District of Ha Giang Province, we collected a single specimen of Achalinus in a lowland region surrounded by secondary forest on karst. We conducted Bayesian and maximum likelihood phylogenetic analyses using multiple mitochondrial protein-coding loci and a ribosomal subunit to ascertain the phylogenetic position of the Ha Giang specimen among currently recognized odd-scaled snake species. The results of those analyses along with morphological differences support this specimen as representing a new species, which we describe as Achalinus zugorum, new species. We provide detailed morphological descriptions and comparisons of the new species as well as brief comments on the biogeography and conservation of Achalinus in northern Vietnam.