thumb|Russell's viper (Daboia russelli) in a sensing moment

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. including:

  • D. s. formosensis <small>(Maki, 1931)</small> occurs in Thailand and is considered a synonym of D. siamensis.
  • D. s. limitis <small>(Mertens, 1927)</small> occurs in Indonesia and is considered a synonym of D. siamensis.
  • D. r. pulchella <small>(Gray, 1842)</small> occurs in Sri Lanka and is considered a synonym of D. russelii.
  • D. r. nordicus <small>(Deraniyagala, 1945)</small> 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. 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

thumb|Head of Russell's viper

thumb|Large fangs

thumbnail|Russell's viper in Pune Zoo

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 body is stout, the cross-section of which is rounded to circular. The dorsal scales are strongly keeled; only the lowest row is smooth. Mid-body, the dorsal scales number 27–33. The ventral scales number 153–180. The anal plate is not divided. The tail is short—about 14% of the total length—with the paired subcaudals numbering 41–68. The following dimensions for a "fair-sized adult specimen" were reported in 1937:

  • Total length
  • Length of tail
  • Girth
  • Width of head
  • Length of head

Distribution and habitat

Russell's viper is found in India, Sri Lanka, Bangladesh, Nepal, and Pakistan. Populations from South-East Asia previously assigned to this species are now considered to be part of a different species, Daboia siamensis. The type locality is listed as "India". More specifically, this would be the Coromandel Coast, by inference of Russell (1796).

Within its range, it can be common in some areas, but scarce in others. The bite may be a snap, or they may hang on for many seconds. The identity of this sensor is not certain, but the nerve endings in the supranasal sac of these snakes resemble those found in other heat-sensitive organs.

Reproduction

Russell's viper is ovoviviparous. in a single litter. At birth, juveniles are in total length. The minimum total length for a gravid female is about . It seems that sexual maturity is achieved in 2–3 years. In one case, it took a specimen nearly 4.5 hours to give birth to 11 young. The quantity of venom produced by individual specimens of D. russelii is considerable. Venom yields for adult specimens have been reported as 130–250&nbsp;mg, 150–250&nbsp;mg, and 21–268&nbsp;mg. For 13 juveniles with an average total length of , the venom yield ranged from 8 to 79&nbsp;mg (mean 45&nbsp;mg). 0.40&nbsp;mg/kg intraperitoneal, about 0.75&nbsp;mg/kg subcutaneous.<!----> For most humans, a lethal dose is about 40–70&nbsp;mg, well within the amount that can be delivered in one bite. In general, the toxicity depends on a combination of five different venom fractions, each of which is less toxic when tested separately. Venom toxicity and bite symptoms in humans vary within different populations and over time.

Symptoms

Envenomation symptoms begin with pain at the site of the bite, immediately followed by swelling of the affected extremity. Bleeding is a common symptom, especially from the gums and in the urine, and sputum may show signs of blood within 20 minutes after the bite. The blood pressure drops, and the heart rate falls. Blistering occurs at the site of the bite, developing along the affected limb in severe cases. Necrosis is usually superficial and limited to the muscles near the bite, but may be severe in extreme cases. Vomiting and facial swelling occur in about one-third of all cases. Other scientific studies support the hypothesis that D. russelii bites can cause hypopituitarism.

Antivenom treatment

In India, the Haffkine Institute prepares a polyvalent antivenom that is used to treat bites from this species.

Clinical use

Because this venom is so effective at inducing thrombosis, it has been incorporated into an in vitro diagnostic test for blood clotting that is widely used in hospital laboratories. This test is often referred to as dilute Russell's viper venom time (dRVVT). The coagulant in the venom directly activates factor X, which turns prothrombin into thrombin in the presence of factor V and phospholipid. The venom is diluted to give a clotting time of 23 to 27 seconds and the phospholipid is reduced to make the test extremely sensitive to phospholipid. The dRVVT test is more sensitive than the aPTT test for the detection of lupus anticoagulant (an antibody associated with antiphospholipid syndrome), because it is not influenced by deficiencies in clotting factors VIII, IX or XI.

References

Further reading

  • Boulenger GA (1890). The Fauna of British India, Including Ceylon and Burma. Reptilia and Batrachia. London: Secretary of State for India in Council. (Taylor and Francis, printers). xviii + 541 pp. ("Vipera russellii", pp.&nbsp;420–421, Figure 123).
  • Boulenger GA (1896). Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the...Viperidæ. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiv + 727 pp. + Plates I.- XXV. ("Vipera russellii", pp.&nbsp;490–491).
  • Cox M (1991). The Snakes of Thailand and Their Husbandry. Malabar, Florida: Krieger Publishing Company. 526 pp.&nbsp;.
  • Daniels JC (2002). Book of Indian Reptiles and Amphibians Mumbai: Bombay Natural History Society/Oxford University Press. viii + 238pp.
  • Das I (2002). A Photographic Guide to Snakes and other Reptiles of India. Sanibel Island, Florida: Ralph Curtis Books. 144 pp. . (Russell's viper, "Daboia russelii", p.&nbsp;60).
  • Gharpurey K (1962). Snakes of India and Pakistan. Bombay, India: Popular Prakishan. 79 pp.
  • Groombridge B (1980). A phyletic analysis of viperine snakes. Ph-D thesis. City of London: Polytechnic College. 250 pp.
  • Groombridge B (1986). "Phyletic relationships among viperine snakes". In: Proceedings of the third European herpetological meeting; 1985 July 5–11; Charles University, Prague. pp 11–17.
  • Jena I, Sarangi A (1993). Snakes of Medical Importance and Snake-bite Treatment. New Delhi: SB Nangia, Ashish Publishing House. 293 pp.
  • Mahendra BC (1984). "Handbook of the snakes of India, Ceylon, Burma, Bangladesh and Pakistan". Annals of Zoology (Agra, India) 22.
  • Minton SA Jr. (1974). Venom Diseases. Springfield, Illinois: CC Thomas Publishing. 386 pp.
  • Morris PA (1948). Boy's Book of Snakes: How to Recognize and Understand Them. A volume of the Humanizing Science Series, edited by Jaques Cattell. New York: Ronald Press. viii + 185 pp. (Russell's viper, "Vipera russellii", pp.&nbsp;156–157, 182).
  • (in German).
  • Reid HA (1968). "Symptomatology, pathology, and treatment of land snake bite in India and southeast Asia". In: Bucherl W, Buckley E, Deulofeu V (editors). Venomous Animals and Their Venoms. Vol. 1. New York: Academic Press. pp 611–42.
  • Shaw G, Nodder FP (1797). The Naturalist's Miscellany. Volume 9. London: Nodder and Co. 65 pp. (Coluber russelii, new species, Plate 291).
  • 130 pp.
  • Smith MA (1943). The Fauna of British India, Ceylon and Burma, Including the Whole of the Indo-Chinese Sub-region. Reptilia and Amphibia. Vol. III.—Serpentes. London: Secretary of State for India. (Taylor and Francis, printers). xii + 583 pp. ("Vipera russelli", pp.&nbsp;482–485).
  • Tweedie MWF (1983). The Snakes of Malaya. Singapore: Singapore National Printers Ltd. 105 pp. ASIN B0007B41IO.
  • Wall F (1921). Ophidia Taprobanica or the Snakes of Ceylon. Colombo, Ceylon [Sri Lanka]: Colombo Museum. (H.R. Cottle, Government Printer). xxii + 581 pp. ("Vipera russelli", pp.&nbsp;504–529, Figures 91-92).
  • Whitaker R (1978). Common Indian Snakes. New Delhi (India): MacMillan. 85 pp.
  • Zhao EM, Adler K (1993). Herpetology of China. Society for the Study of Amphibians and Reptiles. 522 pp.&nbsp;.
  • Russell's viper at Michigan Engineering. Accessed 5 September 2007.
  • Russell's viper at SurvivalIQ. Accessed 5 September 2007.
  • Mark O'Shea in Sri Lanka at Mark O'Shea. Accessed 5 September 2007.
  • Common Poisonous Snakes in Taiwan at Formosan Fat Tire. Accessed 5 September 2007.
  • . Accessed 5 September 2007.
  • . Accessed 5 September 2007.
  • Toxicology.