Gloydius is a genus of venomous pitvipers endemic to Asia, also known as Asian moccasins or Asian ground pit vipers. Named after American herpetologist Howard K. Gloyd,[2] this genus is very similar to the North American genus Agkistrodon. 24 species are currently recognized.[3]
Species of Gloydius are found in Russia, east of the Ural Mountains through Siberia, Iran, Himalayas from Pakistan, India, Nepal, China, Korea, Japan and the Ryukyu Islands.[1]
Due to the strong morphological similarity, these snakes were classified in the genus Agkistrodon until very recently. However, by 1999 cladistic studies clearly showed that Agkistrodon did not form a clade (indeed, it was not even paraphyletic) and was thus split into several genera.
A new species, G. tsushimaensis, was described by Isogawa, Moriya & Mitsui (1994). It is referred to as the Tsushima island pitviper and is found only on Tsushima Island, Japan.