A new species of the genus Calamaria H. Boie in F. Boie, 1827 (Squamata, Calamariidae) from Xishuangbanna, Yunnan Province, China

A new species of reed snake, <i>Calamaria synergis</i> <b>sp. nov.</b>, is described based on two specimens collected from Mountain Jinuo, Jinghong City, Xishuangbanna Dai Autonomous Prefecture, Yunnan Province, China. The new species is distinguished from its congeners by a unique combination of morphological characters, including eight enlarged maxillary teeth; rostral higher than wide; prefrontal shorter than frontal and contacting the first two supralabials; mental not in contact with anterior chin shields; single preocular and postocular; four supralabials, with the 2^nd and 3^rd contacting the eye; five infralabials; five scales surrounding the paraparietal; ventrals 161-166; subcaudals 20-23, paired; dorsal scales reduced to six rows at the tail base and further to four rows near the terminal subcaudals; tail relatively short (6.6-9.2% of total length), abruptly tapering at the tip; dorsum blackish-brown with a distinct pale nuchal ring; two outermost dorsal scale rows pale khaki with upper margins darkened; ventral surface uniform pale khaki. Phylogenetic analysis of the mitochondrial cytochrome <i>b</i> gene places the new species as sister to <i>C. andersoni</i> and <i>C. yunnanensis</i>, from which it differs by an uncorrected <i>p</i>-distance of 8.7% and 7.9%, respectively. <i>Calamaria synergis</i> <b>sp. nov.</b> is currently known only from tropical evergreen forests of Xishuangbanna at elevations around 1,050 m asl. We propose its conservation status as Data Deficient (DD) following the IUCN Red List categories.