Walterinnesia is a genus of venomous snakes in the familyElapidae. 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.
These snakes are medium in length, with a medium, cylindrical body and a short tail. Their average length is, but they can grow to lengths of. 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 - 23 - 17. Unlike other snakes commonly referred to as "cobras", the black desert cobra rarely rear up or produces a hood before striking in defense.
These species occur in the desert. They can also be found in semi-desert scrubland 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.
Diet
These species feeds mainly on lizards such as skinks, geckos, agamids, other snakes, toads and occasionally mice and birds. They will also readily eat carrion.
Venom
W. aegyptia is highly venomous. The subcutaneous for the venom of W. aegyptia is 0.4 mg/kg. For comparison, the Indian cobra's subcutaneous is 0.80 mg/kg, while the Cape cobra's subcutaneous is 0.72 mg/kg. This makes W. aegyptia 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.
