On the validity of Hebius sauteri maximus (Malnate, 1962) (Squamata, Natricidae), with the redescription of H. maximus comb. nov. and H. sauteri (Boulenger, 1909)

Hebius sauteri (Boulenger, 1909) has been long recognized as a widely distributed species with three subspecies, namely Hebius sauteri sauteri from Taiwan Island and southeastern China, Hebius sauteri bourreti (Malnate, 1962) from northern Vietnam, and Hebius sauteri maximus (Malnate, 1962) from Sichuan, southwestern China. However, the validity of these subspecies of the H. sauteri complex has not been evaluated. In the current study, we re-evaluate the taxonomic status of H. s. maximus based on morphological and molecular evidence. Molecular phylogenetic results indicate that H. s. maximus is a distantly diverged clade with respect to H. s. sauteri, and that H. s. maximus is morphologically distinguishable from the nominative subspecies. Therefore, our results support the validity of H. s. maximus and we elevate it to full species status, namely Hebius maximus comb. nov. The distribution range of H. sauteri is revised according to our proposed taxonomic change. Furthermore, detailed redescription, natural history, and coloration of both H. sauteri and H. maximus and comments on the validity of H. s. bourreti are also provided.