On the Taxonomy of Atretium yunnanensis Anderson, 1879 (Squamata: Natricidae), with Redescriptions and Natural History Data of the Poorly Known Species

Atretium yunnanensis was originally recognized as a variant of Atretium schistosum. It was subsequently elevated to full species status and has long been assigned to the natricine genus Atretium. However, the taxonomic status of A. yunnanensis still remained unevaluated by a polyphasic taxonomic approach. In the present study, the generic assignment of A. yunnanensis was re-evaluated based on both morphological and genetic evidences from newly collected specimens (including topotypes). The genus Atretium was recovered as polyphyletic with reference to A. yunnanensis, whereas A. yunnanensis was nested within the genus Fowlea Theobald, 1868. Moreover, Atretium yunnanensis is morphologically closer to the members of Fowlea rather than the genus Atretium. Since the continuous recognition of A. yunnanensis in the genus Atretium will preclude the monophyly of genus Atretium, we transfer A. yunnanensis to the genus Fowlea. In addition, we provided detailed descriptions of Fowlea yunnanensis, including hemipenial description, colored photos, distribution map, and natural history.