Integrative taxonomy identifies a new species of Trimeresurus Lacépède, 1804 (Reptilia: Serpentes: Viperidae) from Yunnan Province, China

The genus Trimeresurus currently contains at least 56 recognized species of venomous terrestrial to arboreal species distributed across South and Southeast Asia. We collected several specimens of the subgenus Viridovipera in Yunnan Province, China in recent years. Based on morphological characters and phylogenetic analysis, we confirm that Trimeresurus yunnanensis is distributed in the west of the Honghe River in Yunnan Province and the Trimeresurus species living along the lower reaches of the Honghe River Basin and adjacent areas is an undescribed taxon. The new species Trimeresurus hongheensis sp. nov. can be distinguished from all known congeners by the pairwise genetic divergence in the mitochondrial cytochrome-b (p-distance≥5.0%) and 16S rRNA gene fragment (p-distance≥0.5%), and morphologically by the combination of the following characters: (1) hemipenes short and strongly spinose, with deep bifurcation; (2) a white postocular stripe bordered above and below by red or only a white postocular stripe present in males; postocular stripe white or absent in females; (3) the ventrolateral stripe is red (below) and white (above) in males and white in females; (4) iris brick red or sepia in males; iris yellow or rusty-red in females; (5) VEN 150–165 in males and 157–165 in females; SC 61–76 in males and 56–61 in females; (6) dorsal tail mostly rusty red; (7) 9–12 cephalic scales; (8) 19 or 21 dorsal scale rows at mid-body; (9) first supralabial completely separated from the nasal scale.