A new species of colubrid snake,Lycodon cathayasp. nov., is described based on two adult male specimens collected from Huaping Nature Reserve, Guangxi, southern China. In a phylogenetic analyses, the new species is shown to be a sister taxon to the clade composed ofL. futsingensisandL. namdongensiswith low statistical support, and can be distinguished from all known congeners by the significant genetic divergence in the mitochondrial cytochromebgene fragment (p-distance ≥ 7.9%), and morphologically by the following combination of characters: (1) dorsal scales in 17–17–15 rows, smooth throughout; (2) supralabials eight, third to fifth in contact with eye, infralabials nine; (3) ventral scales 199–200 (plus two preventral scales), subcaudals 78; (4) loreal single, elongated, in contact with eye or not, not in contact with internasals; (5) a single preocular not in contact with frontal, supraocular in contact with prefrontal, two postoculars; (6) maxillary teeth 10 (4+2+2+2); (7) two anterior temporals, three posterior temporals; (8) precloacal plate entire; (9) ground color from head to tail brownish black, with 31–35 dusty rose bands on body trunk, 13–16 on tail; (10) bands in 1–2 vertebral scales broad in minimum width; (11) bands separate ground color into brownish black ellipse patches arranged in a row along the top of body and tail; (12) elliptical patches in 3–6 scales of the vertebral row in maximum width; (13) ventral surface of body with wide brownish black strip, margined with a pair of continuous narrow greyish white ventrolateral lines. With the description of the new species, 64 congeners are currently known in the genusLycodon, with 16 species occurring in China.
