Search

Snakes of the natricid genus Trachischium Günther, 1858 are distributed in the southern Himalayas. Due to their secretive nature and fossorial habits, their taxonomy, evolution, and ecology remain poorly understood. Based on a multilocus molecular phylogeny and morphological comparisons we explored Trachischium systematics. Results indicated that all representatives of Trachischium form a strongly supported clade with their close relatives in Blythia, and that Blythia is nested within Trachischium. Therefore, we suggest that Blythia is synonymous with Trachischium. Molecular data and morphological comparisons revealed cryptic diversity within Trachischium, and thus we describe one new species from China while also excluding T. guentheri and T. tenuiceps from the Chinese fauna. [ABSTRACT FROM AUTHOR]

Although several phylogeographic studies of Asian snakes have been conducted, most have focused on pitvipers, with non‐venomous snakes, such as colubrids or natricids, remaining poorly studied. The Chinese keelback water snake (Trimerodytes percarinatus Boulenger) is a widespread, semiaquatic, non‐venomous species occurring in China and southeastern Asia. Based on mitochondrial DNA (mtDNA) and single nucleotide polymorphism (SNP) data, we explored the population genetic structure, genetic diversity, and evolutionary history of this species. MtDNA‐based phylogenetic analysis showed that T. percarinatus was composed of five highly supported and geographically structured lineages. SNP‐based phylogenetic analysis, principal component analysis, and population structure analysis consistently revealed four distinct, geographically non‐overlapping lineages, which was different from the mtDNA‐based analysis in topology. Estimation of divergence dates and ancestral area of origin suggest that T. percarinatus originated ~12.68 million years ago (95% highest posterior density: 10.36–15.96 Mya) in a region covering southwestern China and Vietnam. Intraspecific divergence may have been triggered by the Qinghai‐Xizang Plateau uplift. Population demographics and ecological niche modeling indicated that the effective population size fluctuated during 0.5 Mya and 0.002 Mya. Based on the data collected here, we also comment on the intraspecific taxonomy of T. percarinatus and question the validity of the subspecies T. p. suriki. [ABSTRACT FROM AUTHOR]

Although several phylogeographic studies of Asian snakes have been conducted, most have focused on pitvipers, with non‐venomous snakes, such as colubrids or natricids, remaining poorly studied. The Chinese keelback water snake (Trimerodytes percarinatus Boulenger) is a widespread, semiaquatic, non‐venomous species occurring in China and southeastern Asia. Based on mitochondrial DNA (mtDNA) and single nucleotide polymorphism (SNP) data, we explored the population genetic structure, genetic diversity, and evolutionary history of this species. MtDNA‐based phylogenetic analysis showed that T. percarinatus was composed of five highly supported and geographically structured lineages. SNP‐based phylogenetic analysis, principal component analysis, and population structure analysis consistently revealed four distinct, geographically non‐overlapping lineages, which was different from the mtDNA‐based analysis in topology. Estimation of divergence dates and ancestral area of origin suggest that T. percarinatus originated ~12.68 million years ago (95% highest posterior density: 10.36–15.96 Mya) in a region covering southwestern China and Vietnam. Intraspecific divergence may have been triggered by the Qinghai‐Xizang Plateau uplift. Population demographics and ecological niche modeling indicated that the effective population size fluctuated during 0.5 Mya and 0.002 Mya. Based on the data collected here, we also comment on the intraspecific taxonomy of T. percarinatus and question the validity of the subspecies T. p. suriki. [ABSTRACT FROM AUTHOR]

Lycodon gammiei (Blanford, 1878), a rarely encountered species of Asian snake, is characterized by ambiguous systematics and biology. Based on a sole specimen of L. gammiei rediscovered in southeastern Xizang, China, we conduct a detailed morphological examination and description, and investigate the systematic position of this species. Morphologically, the newly collected specimen is closely aligned with specimens previously described. Mitochondrial DNA-based phylogenetic analyses reveal that L. gammiei constitutes an independent evolutionary lineage, forming a clade with L. fasciatus (Anderson, 1879), L. gongshan Vogel & Luo, 2011, L. butleri Boulenger, 1900, and L. cavernicolus Grismer, Quah, Anuar, Muin, Wood & Nor, 2014. The closest genetic distance between L. gammiei and its congeners was 10.2%. The discovery of L. gammiei in Medog County, China, signifies an eastward expansion of its known geographical distribution. [ABSTRACT FROM AUTHOR]

• The monophyly of Trimerodytes is strongly supported, with T. yapingi as the basal to the remaining species. • Trimerodytes likely originated in Hengduan Mountains (eastern Tibetan Plateau) in western China at 23.93 Ma (17.09–31.30). • The validity of T. yunnanensis is supported. The Asian water snake genus Trimerodytes (formerly Sinonatrix) is endemic to East and Southeast Asia. Although several species have been included in various phylogenetic studies previously, the evolution and relationships among members of this genus as a whole remain unexplored. In this study, we report the sequencing two protein-coding mitochondrial gene fragments (MTCYB and ND2) and three nuclear genes (c-mos , NT3 , and Rag1), reconstruct interspecific phylogeny, and explore biogeography for the genus Trimerodytes. Both Bayesian inference and maximum likelihood analyses consistently recover the monophyly of Trimerodytes with strong support, with T. yapingi the sister-group to the remaining species. The divergence date and ancestral area estimation suggest that Trimerodytes likely originated in Hengduan Mountains (eastern Tibetan Plateau) in western China at 23.93 Ma (95% HPD: 17.09–31.30), and intraspecific divergence began at about 4.23 Ma (95% HPD: 2.74–6.10). Analyses support the validity of T. yunnanensis. [ABSTRACT FROM AUTHOR]