Designation of the Lectotype for Tropidophorus laotus(Reptilia:Scincidae)and Description of A New Closely Related Species from Southern Yunnan Province, China

Despite continuous progress made on the taxonomy of the genus Tropidophorus, the Lao Water Skink, T. laotus, is only known from brief descriptions of its syntypes in historical literature. Here we designate a lectotype and paralectotype of the species, redescribe the species based on the type series and newly collected topotypes, provide the first colored photographs of taxonomically-verified individuals, and estimate its phylogenetic position using mitochondrial DNA data for the first time.Using these comparable data, we confirm that the previously identified “T. berdmorei” population from southern Yunnan Province, China, represents a distinct new species that is closely related and morphologically similar to T. laotus, but differs from true T. laotus by having considerable genetic divergence(4.7%–4.8% for 12S, 3.2%–4.2% for 16S)and distinct morphological characters(e.g., undivided frontonasal scales and a distinct color pattern of the throat). The southern Yunnan population is therefore described as a new species. With the above newly acquired data, we update the checklist and the provincial-level distribution of the genus Tropidophorus in China and compile an updated key to all recognized species of the genus from China and Indochina.