A New Species of Plateau Pit Viper (Reptilia: Serpentes: Gloydius) from the Upper Lancang (=Mekong) Valley in the Hengduan Mountain Region, Tibet, China.

The Plateau Pit Viper, Gloydius strauchi, from southwest and central China has long been considered a single, widespread species despite suspicion that it represents a potential complex of distinct evolutionary lineages. Although series of works were published on the G. strauchi species complex over the last 10 yr, species boundaries and diagnostic features of different members of the complex have remained poorly understood. Combining both morphological and genetic data, we re-evaluate taxonomic statuses of populations of G. strauchi in southwest China and describe the eastern Tibetan populations as a new species. The new species is most closely related to G. monticola phylogenetically, and it differs from all congeners by having a matte dorsal body scale texture, oval and robust head shape, distinct body ornamentation and coloration, and unique hemipene morphology. In addition, we provide the first updated diagnostic key to all recognized members of the G. strauchi species complex, and discuss ongoing taxonomic problems associated with cryptic diversity within the genus in China. [ABSTRACT FROM AUTHOR]