The taxonomic history of the Amphiesma sensu lato has long been confused, and this complex was recently divided into three genera, i.e., Amphiesma Duméril, Bibron, and Duméril, 1854 sensu stricto, Hebius Thompson, 1913, and Herpetoreas Günther, 1860. Being the least known genus, Herpetoreas is reviewed herein through an integrative taxonomic approach. Our results indicate that specimens previously referred to Hebius parallelus (Boulenger, 1890) from Mêdog, Tibet, China, represent a new species. We describe here this new species and refer it to the genus Herpetoreas; therefore, we remove Hebius parallelus from the Chinese herpetofauna. A diagnostic key to all the species of Herpetoreas is also provided. Furthermore, we re-evaluate the diagnostic characters of the three genera formerly confused with Amphiesma, namely, Amphiesma, Hebius, and Herpetoreas. We provide a key to these three morphologically similar genera. We also emphasize the importance of the maxillary teeth and hemipenial morphology in the generic diagnosis in the family Natricidae.

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 partition of 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 H. s. maximus is morphologically distinguishable from the latter nominate subspecies. Therefore, we support the validity of H. s. maximus and elevate it to full species status, namely Hebius maximus comb. nov., and we revise the distribution range of H. sauteri 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.

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 maximuscomb. 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.