Added 10 January 2010. Last updated 11 March 2014: updated details for X. hainensis and X. unicolor and Bibliography.
A family from SE Asia made up of a single genus and until recently a single species. The classification of Xenopeltis has always been a bit of a problem for taxonomists as despite initial appearances it is not a colubrid.
Zug, Witt and Caldwell give the following characteristics for the family: blunt head, cylindrical bodies, short tails and large ventral scales. Cranially, two common carotid arteries; teeth on premaxillaries; longitudinally oriented maxillaries with solid teeth; optic foramina perforate frontal-parietal sutures; mandible lacks coronoid; dentary bears numerous small teeth; infrared receptors lacking. Girdle and limb vestiges absent; intracostal arteries arise from dorsal aorta at nearly every trunk segment; left lung large, tracheal lung absent; both left and right oviducts are well developed. Although often described as nocturnal they may also forage during the day, at least some of the year. Commonly associated with water but found in variety of habitats. Reproduction is oviparous.
Xenopeltis are sometimes seen in captivity, but do not seem to be popular subjects. In a way this seems to be a bit of a mystery, given their comparative beauty, although their nocturnal/crepuscular and fossorial (burrowing) lifestyle may make them less interesting objects of display. On the other hand, at least one source considers them to acclimate poorly to captivity (see Links). It may be that methods of capturing wild-caught animals, and their subsequent handling during importation, are less than ideal. See Walls for terrarium suggestions: the latter author does not consider them overly difficult. Certainly there would appear here to be a place for captive breeding by dedicated herpetoculturists if the Sunbeam Snakes are to have a place in terrarium keeping in the future.
|
Genus |
Common Name |
Distribution |
Size |
Notes |
|
Xenopeltis |
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|
X. hainensis |
Hainan Sunbeam Snake |
China (Guangxi east to Zhejiang and south to Hainan) |
SVL 48-58 cm; TL 52-62 cm |
First described in 1972. Scalation details: nostril between 2 small nasals; 1 postocular; 7 supralabials, of which 4th and 5th enter the eye. Ventral scalation: 152-157. Other: 16-18 pairs of subcaudals; 22-24 teeth on maxillary. Coloration: dorsally indigo-brown with metallic sheen; 2 series of white longitudinal spots; underside of head light indigo grey or light brown; underside of body and tail base greyish-white; remainder of underside of tail indigo brown. [SOURCES: Hu et al, Walls, Zhao and Adler] |
|
X. unicolor |
Common Sunbeam Snake |
India (Nicobar Islands), Myanmar, W Malaysia, Borneo, Philippines (Sula and Palawan), Indonesia, Sri Lanka, Thailand, Laos, Vietnam, China |
SVL 40-100cm (Philippines), max 1.25m (India, SE Asia) |
In the Philippines, found in lowland habitat; in India, swamps and lowland forests; in SE Asia, lowlands and hills up to 1,300m. Food consists of other snakes, frogs, snails and rodents [Alcala], plus ground-nesting birds and amphibians [Das] and lizards [Cox et al]. Scalation details: nostril between 2 small nasals; 2 postoculars; 8 supralabials, of which 4th and 5th enter the eye; mental groove present. Dorsal scalation: 15 rows at midbody. Ventral scalation: 170-195, large (Walls cites 164-196). Subcaudals: 24-30, divided. Other: snout depressed and rounded; head flattened; body cylindrical; small eyes with vertically elliptic pupils; teeth small, equal, closely set, and very numerous (4 on each side of premaxillary), 35-45 teeth on maxillary. Coloration: overall iridiscent brown, with each scale being light-edged; ventrally white or cream. Reproduction: in India, clutches of 6-17 eggs; juveniles have pale yellow or cream colour. [SOURCES: Alcala, Boulenger, Cox, Das, Hu et al, Walls] |
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.
Boas Rosy and Ground, Jerry G Walls, TFH, 1994. Includes a bonus chapter with sections on the Burrowing Python Calabria reinhardtii, the Neotropical Python Loxocemus bicolor and the Sunbeam Snakes, Xenopeltis sp. Recommended.
Herpetology of China, Er-mi Zhao and Kraig Adler, SSAR, 1993. Catalogue of practically every reptile and amphibian species found in mainland China, Hongkong, Macao, Tibet and Taiwan. Helpful here in giving range details for China.
The Book of Indian Reptiles and Amphibians, J C Daniel, Bombay Natural History Society, Oxford University Press, Oxford, 2002.
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malysia, Singapore and Thailand, Merel J Cox, Peter Paul van Dijk, Jarujin Nabhitabhata, Kumthorn Thirakhupt, New Holland, 2006.
Herpetology, An Introductory Biology of Amphibians and Reptiles, 2nd edition, George R Zug, Laurie J Vitt, Janalee P Caldwell, Academic Press, 2001. Includes classification details for the families of the Reptilia and Amphibia.
Wikipedia article on Sunbeam Snakes
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