Gonyosoma is an Asian genus chiefly-known for the very attractive but tricky G. oxycephalum, the Red-Tailed Rat Snake. The genus has also become a receptacle for a few other species formerly assigned to Elaphe, although there is apparently some disagreement over exactly which ones.
G. oxycephalum seems to be the only species that occurs regularly in hobbyist literature and has an unenviable reputation for being difficult. The Bartletts recommend this species only to the most advanced keepers and zoological institutions.
|G. frenata, Assam Green Trinket Snake||G. jansenii||G. oxycephalum, Red-Tailed Rat Snake|
|Scientific Name||Common Name||Distribution||Size||Notes|
||Assam Green Trinket Snake||Assam (India), SE China to SW Sichuan, N Vietnam||2½'||Formerly considered an Elaphe species, this is an attractive snake, being an overall brightish green with paler sides. It can be distinguished from the similarly-coloured E. prasina by its black bar passing across the eye above the labial scales, which is lacking in E. prasina. Another distinguishing mark is the loreal scale which is fused to the prefrontal scale. It is not supposed to be widely distributed across its range, which is mainly mountainous, and physical and political obstacles further limit its availability. Staszko and Walls recommend a moderately heated terrarium with overwintering for reproductive purposes.
|G. jansenii||Indonesia (Sulawesi [Celebes])|
|G. oxycephalum||Red-Tailed Rat Snake||SE Asia, Indonesian archipelago||5-8½'||The consideration of this species as a true rat snake now seems to be in doubt, and indeed two other similarly doubtful species, E. frenata and E. prasina, have been placed in this genus by some authorities. Not much is known of its natural history, although it seems to inhabitat mangrove swamps with brackish water in at least some parts of its range: Alcala describes it as arboreal and large confined to forests within the Philippines. Nevertheless G. oxycephalum is a beautiful snake, being often a glossy shade of green with the red tail of its common name. Some specimens from the Indonesian part of its range are an attractive grey colour, lacking the red on the tail but instead often having yellow or green heads. Unfortunately this is probably one of the most difficult snakes to keep alive in captivity. Virtually all are wild-caught and arrive with heavy parasite loads, respiratory problems, refusal to feed and a highly aggressive temperament. Add to that the need for a spacious arboreal cage in a quiet area and the possibility that you may need to entice it to feed with birds rather than prekilled mice, and you can see why most hobbyists avoid it. The Bartletts recommend captive temperatures of up to 88 deg F by day, dropping to 75 deg F at night, a natural photoperiod and fairly high humidity. They also recommend it for only the most advanced hobbyists or zoological institutions. Scalation details [Alcala]: 30 scale rows at neck, 25 at midbody: scales smooth on the anterior part of the body but keeled on posterior half, pointing posteriorly: 240-255 ventrals, 120-135 subcaudals in double rows: anal shield divided. Coloration: Filipino specimens are overall bright yellowish to whitish green dorsally, with olive heads and greenish labials: the tail varies between yellowish and flesh colour: ventrally it is more yellowish than laterally: chin, throat and belly are cream yellow, and the outer edges of the ventrals are greenish.
Guide to Philippine Flora and Fauna. Volume X, Amphibians and Reptiles, Prof. Angel C Alcala, Natural Resources Management Centre, Ministry of Natural Resources and University of the Philippines, 1986. Very useful field guide to the herps of this area, which is usually under-represented in literature. One slight drawback is that the photographs are black-and-white and the descriptions of colour for many species are drawn from preserved specimens: otherwise this book is to be recommended if you can obtain a copy.
Herpetology of China, Er-mi Zhao and Kraig Adler, Society for the Study of Amphibians and Reptiles, 1993.
Rat Snakes: A Hobbyist's Guide to Elaphe & Kin, Ray Staszko & Jerry G Walls, TFH 1994.
Corn Snakes and Other Rat Snakes (Complete Pet Owner's Manual) by R D & P Bartlett, Barrons Pet Series 1996.
Index of ratsnake articles (on this site).
Reptilia-Denmark has an introductory article and some good photographs of G. oxycephalum.
Eco-Rep has an introductory article and describes experience of both imported and captive-bred G. oxycephalum.
www.gonysoma.de is a German-language site largely dedicated to snakes and in particular G. oxycephalum.
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