Russell's Viper

Russell's viper (Daboia russelii) is a species of highly venomous snake in the family Viperidae. The species is native to South Asia. It was described in 1797 by George Shaw and Frederick Polydore Nodder. It is named after Patrick Russell. Known for its extremely painful bite, it is considered one of the "Big Four" venomous snake species in the region.

Taxonomy

Coluber russelii was the name proposed by George Shaw who described the species in 1797 based on a specimen presented to the British Museum by Patrick Russell. Russell described the species in 1796 and confirmed its highly venomous nature by experimenting on chickens and dogs. He added the native people called it katuka retula poda.

Analysis of morphological and mitochondrial DNA data shows that the eastern subspecies of Russell's viper should be considered a separate species, Daboia siamensis.

A number of other subspecies may be encountered in literature. including:

D. s. formosensis (Maki, 1931) occurs in Thailand and is considered a synonym of D. siamensis.

D. s. limitis (Mertens, 1927) occurs in Indonesia and is considered a synonym of D. siamensis.

D. r. pulchella (Gray, 1842) occurs in Sri Lanka and is considered a synonym of D. russelii.

D. r. nordicus (Deraniyagala, 1945) occurs in northern India and is considered a synonym of D. russelii.

The correct spelling of the species, D. russelii, has been, and still is, a matter of debate. Shaw and Nodder (1797), in their account of the species Coluber russelii, named it after Patrick Russell, but apparently misspelled his name, using only one "L" instead of two. McDiarmid et al. (1999) are among those who favor the original misspelling, citing Article 32c (ii) of the International Code of Zoological Nomenclature. Others, such as Zhao and Adler (1993) favor russellii.

Etymology

The species is named after Patrick Russell. The genus name is thought to be a latinisation of the Hindi word daboyā meaning "that lies hid", or "the lurker".

English common names of the Russell's viper include chain viper, Indian Russell's viper, seven pacer, chain snake, and scissors snake.

Description

The head is flattened, triangular, and distinct from the neck. The snout is blunt, rounded, and raised. The nostrils are large, each in the middle of a large, single nasal scale. The lower edge of the nasal scale touches the nasorostral scale. The supranasal scale has a strong crescent shape and separates the nasal from the nasorostral scale anteriorly. The rostral scale is as broad as it is high.

The crown of the head is covered with irregular, strongly fragmented scales. The supraocular scales are narrow, single, and separated by six to nine scales across the head. The eyes are large, flecked with yellow or gold, and surrounded by 10–15 circumorbital scales. The snake has 10–12 supralabials, the fourth and fifth of which are significantly larger. The eye is separated from the supralabials by three or four rows of suboculars. Of the two pairs of chin shields, the front pair is notably enlarged. The two maxillary bones support at least two, and at the most five or six, pairs of fangs at a time: the first are active and the rest replacements. The fangs attain a length of 16.5 mm (0.65 in) in the average specimen.