A new snake species of the genus Gonyosoma Wagler, 1828 (Serpentes: Colubridae) from Hainan Island, China

Based on morphological and molecular comparisons, the Hainan Island rhinoceros snake population differs from the mainland G. boulengeri populations. [...]we treat the Hainan Island population as a new species. Morphological data, including 11 meristic characters, were examined as follows: loreal (Lor), preocular (PrO), postocular counts (PtO), supralabial (SL), infralabial (IL), temporal counts (Tem), dorsal scale row numbers (DSR, counting at one head length behind head, at midbody, and at one head length before vent, respectively), ventral counts (VEN, according to Dowling (1951)), subcaudal counts (SC, terminal scute excluded from number of subcaudals), preanal plate (PreAn), and infralabial contact with first pair of chin shields (IL-CS). Nine measurements were also recorded as follows: total length (TL, distance from tip of snout to tip of tail), snout-vent length (SVL, distance from tip of snout to posterior margin of cloaca), tail length (TaL, distance from posterior margin of cloaca to tail tip), head length (HL, posterior edge of jaw to tip of snout), head width (HW, maximum head width), eye length (EL, maximum vertical eye length), eye width (EW, maximum horizontal eye width), head height (HH), and rostral width (RW). The intraspecific distances among the six Hainan Island rhinoceros snakes ranged from 0.0% to 0.6%, whereas the distances between the Hainan rhinoceros snake and continental sister species, G. boulengeri, ranged from 2.5% to 3.0%. [...]combined with morphological data, the specimens from Diaoluoshan, Hainan, China, are considered a new species and described below.