Ahaetulla, commonly referred to as Asian vine snakes or Asian whip snakes, is a genus of colubrid snakes distributed throughout tropical Asia. They are considered by some scientists to be mildly venomous and are what is commonly termed as 'rear-fanged' or more appropriately, opisthoglyphous, meaning their enlarged teeth or fangs, intended to aid in venom delivery, are located in the back of the upper jaw, instead of in the front as they are in vipers or cobras. As colubrids, Ahaetulla do not possess a true venom gland or a sophisticated venom delivery system. The Duvernoy's gland of this genus, homologous to the venom gland of true venomous snakes, produces a secretion which, though not well studied, is considered not to be medically significant to humans. Green-colored members of this genus are often referred to as green vine snakes. They are not to be confused with the "green vine snake" Oxybelis fulgidus, which convergently appears very similar but is found in Central and South America. Taxonomy Their closest relative is the monotypic genus Proahaetulla, which Ahaetulla diverged from in the mid-Oligocene. From here, the clade containing Proahaetulla and Ahaetulla is a sister group to the genus Dryophiops, and the clade containing all three of these genera is a sister group to the clade containing the bronzeback snakes (Dendrelaphis) and flying snakes (Chrysopelea). In 2020, an analysis of Ahaetulla nasuta, Ahaetulla dispar, and Ahaetulla pulverulenta throughout their range found them to represent species complexes containing several undescribed or formerly synonymized species, leading to the description of A. borealis, A. farnsworthi, A. malabarica, A. travancorica, and A. sahyadrensis, as well as the resurrection of A. oxyrhyncha and A. isabellina. Ahaetulla nasuta and Ahaetulla pulverulenta, formerly considered to have much wider ranges, are now considered endemic to Sri Lanka. Geographic range They are found from Sri Lanka and India to China and much of Southeast Asia. Sri Lanka and the Western Ghats of India are major hotspots of diversity for the genus, with 10 of the 17 currently-described species being endemic to these regions. Species The taxonomy of vine snakes is not well-documented, and literature varies widely, but there are 18 currently accepted species in the genus Ahaetulla: Ahaetulla anomala (Annandale, 1906) - Variable colored vine snake (possibly conspecific with A. oxyrhyncha) Ahaetulla borealis Mallik, Srikanthan, Pal, Princia D'Souza, Shanker & Ganesh, 2020 - Northern Western Ghats vine snake Ahaetulla dispar (Günther, 1864) -