Expanded description and distribution of Opisthotropis tamdaoensis Ziegler, David & Vu, 2008 (Squamata, Natricidae), first record from Yunnan Province of China

On the basis of newly-collected <i>Opisthotropis</i> specimens from Hekou, Yunnan, China, this study reports the first country record of <i>Opisthotropis tamdaoensis</i> from China. The Chinese <i>Opisthotropis tamdaoensis</i> population totally agrees with the original description of this species and revealed only a minor genetic distance (lower than 2.9%) in the mitochondrial gene fragment of the cytochrome <i>b</i> (<i>Cytb</i>) compared with the topotypic population. Based upon the our newly-collected specimens and published data, we revised the diagnosis of <i>Opisthotropis tamdaoensis</i>: nasal not divided below nostril;loreal usually 1, not in contact with internasals;pre-oculars 1-2, postoculars 2 subocular, usually 1;anterior temporals 1-2, posterior temporals 2-4;supralabials usually 9, only the fifth or fifth to sixth supralabial (rarely none) in contact with the orbit;infralabials usually 9-10;first pair of chin shields longer than the second pair;dorsal scales smooth anteriorly, keeled posteriorly, in (17-19)-17-17 rows;tails relatively short, TaL/TL 0.143-0.161;pre ventrals 0-4, ventrals 160-176, precloacal divided; 48-56 divided subcaudals;uniform olive-grey dorsum, with a dark longitudinal lateral stripe within the dark flank colouration, ventral side pale or light yellow, without sharp transition towards the dark dorsal colouration, subcaudal region may bear dark mottling. This finding broadly extends our understanding of this poorly-known snake species and raises the total known <i>Opisthotropis</i> number in China to 14. Moreover, this study reports the second <i>Opisthotropis</i> species in Yunnan Province, China.