Walterinnesia is a genus of venomous snakes in the family Elapidae. The genus contains two species, known commonly as desert black snakes or black desert cobras, which are endemic to the Middle East. Walterinnesia aegyptia was long considered to be the only species within the genus. However, it was recently found that the eastern populations actually represent a different species, Walterinnesia morgani. W. aegyptia is entirely black in color, and has highly shiny scales. W. morgani differs in having a juvenile pattern of reddish crossbars on the back, and lower average ventral and subcaudal scale counts.
|Scientific classification |
The generic name, Walterinnesia, is in honor of Walter Francis Innes Bey (1858–1937), who was a physician and zoologist in Egypt.
These snakes are medium in length, with a medium, cylindrical body and a short tail. Their average length is 0.5 meters (1 ft 8 in), but they can grow to lengths of 1.8 meters (5 ft 11 in). Their head is moderately small, broad, flattened and slightly distinct from the neck. The snout is broad, sharply edged with a distinct canthus rostralis. The eyes are small in size with round pupils. Dorsal scales are smooth anteriorly and weakly keeled on the posterior part of the body and tail. They are very glossy throughout. Dorsal scale count 27 (24 to 29) - 23 (21 - 25) - 17. Unlike other snakes commonly referred to as "cobras", the black desert cobra rarely rear up or produces a hood before striking in defense.
Geographical range and habitat
They are native to the Middle East. Walterinnesia aegyptia is found in the countries of Egypt, Lebanon, Jordan, Israel, northwestern Saudi Arabia, and Kuwait. It may also be found in areas of Syria that border Lebanon, as well as the deserts of Qatar.
These species occur in the desert (excluding completely sand deserts such as the ad-Dahna Desert). They can also be found in semi-desert scrublands and rocky terrain, extending into the foothills of vegetated Mediterranean terrain. They are also often found near human habitation in irrigated agricultural settlements.
Behaviour and diet
The desert black snakes are nocturnal and are strictly terrestrial snakes. They are most active around midnight. They actively pursue and forage for their prey and rather than envenomate their prey with an open mouth, they'll usually bite their prey sideways at short distances and often use constriction and suffocation techniques in addition to their venom to kill their prey. There are reports of these snakes being aggressive when molested, but like most snakes, they will usually try to escape rather than immediately bite or face their threat. Venom is not injected immediately when they bite, but released seconds later with chewing movement.
W. aegyptia is highly venomous. The subcutaneous LD50 for the venom of W. aegyptia is 0.4 mg/kg. For comparison, the Indian cobra's (Naja naja) subcutaneous LD50 is 0.80 mg/kg, while the Cape cobra's (Naja nivea) subcutaneous LD50 is 0.72 mg/kg. This makes W. aegyptia (the desert black snake) a more venomous snake than both. Like many elapid snakes, the venom is primarily neurotoxic and effects of envenenomation are from systemic circulation of the toxins rather than from local effect on tissue near the site of injection.
A survey of the literature revealed only a few clinical cases reported. Most of the information concerning W. aegyptia was collected from laboratory and animal studies.
- "Walterinnesia ". ITIS (Integrated Taxonomic Information System).
- Nilson, Göran; Rastegar-Pouyani, Nasrullah (2007). "Walterinnesia aegyptia Lataste, 1887 (Ophidia: Elapidae) and the status of Naja morgani Mocquard 1905". Russian Journal of Herpetology 14: 7-14.
- Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Walterinnesia aegyptia, p. 130).
- Clinical Toxinology Resources - Walterinnesia aegyptia
- Ugurtas IH, Papenfuss TJ, Orlov NL (2001). "New record of Walterinnesia aegyptia Lataste, 1887 (Ophidia: Elapidae: Bungarinae) in Turkey". Russian Journal of Herpetology 8: 239–245.
- LD50 Menu
- Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson J, Loscalzo J (editors) (2012). Harrison's Principles of Internal Medicine, 18th Edition. New York: McGraw-Hill. 4,012 pp. ISBN 978-0071748896.
- Lataste F (1887). "Description d'un nouveau genre et d'une nouvelle espèce d'ophidien protéroglyphe d'Égypte ". Le Naturaliste, Journal des échanges et des nouvelles 9: 411-413. (Walterinnesia, new genus, p. 411; W. aegyptia, new species, pp. 411-413). (in French).
- Mocquard F (1905). "Diagnoses de quelques espèces nouvelles de Reptiles ". Bulletin du Muséum d'Histoire Naturelle, Paris 11: 76-79. (Naja morgani, new species, pp. 78-79). (in French).