Formosan odd-scaled snake, Taiwan burrowing snake
Achalinus formosanus, common name Formosan odd-scaled snake or Taiwan burrowing snake, is a non-venomous snake in family Xenodermidae that is found in Taiwan and in the southern Ryukyu Islands (Japan).
Achalinus formosanus is a small snake growing to a total length of about 90 cm (35 in). The whole body is iridescent under light. Head is small, oval, and without distinct neck. Body is slender and tail is moderately short. Eyes are small, bead-like; iris is black and indistinct. Upper head, body and tail is uniform olive, grayish tan, or black. Mid-dorsal row of scales on body and tail show a dark longitudinal line. Ventral surface is olive-yellow or dark gray. The young are usually black.
Achalinus formosanus formosanus is known from central and southern Taiwan at elevations of 1,000–2,000 m (3,300–6,600 ft) asl. Achalinus formosanus chigirai occurs at low altitudes (below 200 m (660 ft)) on the Iriomote-jima and Ishigaki Islands, both belonging to the Yaeyama Group.
It is a nocturnal, terrestrial snake that probably preys on earthworms, slugs, and frogs. It is non-venomous and not aggressive. It is oviparous.