Bitis caudalis | |
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Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Subphylum: | Vertebrata |
Class: | Reptilia |
Order: | Squamata |
Suborder: | Serpentes |
Family: | Viperidae |
Subfamily: | Viperinae |
Genus: | Bitis |
Species: | B. caudalis |
Binomial name | |
Bitis caudalis (Smith, 1839) |
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Synonyms | |
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Bitis caudalis is a venomous viper species found in the arid region of south-west Africa. Easily distinguished by the presence of a single, large horn-like scale over each eye. No subspecies are currently recognized.[6]
Contents |
A short and stout little viper that usually averages 30–40 cm in length. The largest specimen reported is a female from southern Botswana measuring 51.5 cm.[2]
The arid region of south-west Africa: south-west Angola, Namibia, across the Kalahari Desert of southern Botswana, into northern Transvaal and southwestern Zimbabwe. In South Africa it is found from the northern Cape Province south to the Great Karoo. Type locality: "... the sandy districts north of the Cape Colony..." [South Africa].[1]
Mostly found in sparsely vegetated desert and semi-arid scrub country.[2]
Bites are assumed to be rare and no epidemiological information is available.[4] Little information is available regarding the toxicity and amount of venom produced. Spawls and Branch (1995) report an average yield of 85 mg of wet venom,[2] while Christensen (1971) offers an LD50 value of 1.2 mg/kg IV.[7]
Based on this LD50 value, Spawls and Branch (1995) estimated that about 300 mg of this venom would be required to kill an adult. They regard this venom as one of the weakest of the genus[2] although it must be mentioned that the tests are conducted solely on mice which might have a different reaction from humans to the venom. On the other hand, an older report by the U.S. Navy (1965, 1991) suggests that it is highly toxic and that a number of deaths have occurred as a result.[5][8] According to Broadley and Cock (1975), envenomation symptoms in humans include swelling, severe pain, nausea, vomiting and shock. Blisters and necrotic ulcers may form around the bite site.[4]
The National Antivenom and Vaccine Production Centre in Riyadh, Saudi Arabia, produces a polyvalent antivenin that includes a paraspecific antibody that protects against bites from this species.[9] According to the U.S. Navy (1965, 1991),[5][8] polyvalent antivenins produced by SAMIR and the Pasteur Institute are said to be effective, while Mallow et al. (2003) report that currently available antivenins are of limited effectiveness.[4]
Viljoen et al. (1982) isolated a protein, a neurotoxic phospholipase A2, from the venom, which they called "caudoxin". According to Lee et al. (1983), this is a presynaptic toxin similar to bungarotoxin, but with different binding sites.[4]
A number of authors, including Mertens (1955), use a trinomial to refer to this species, even though no subspecies are recognized.[1]