The horned adder (''Bitis caudalis'') is a

viper Vipers are snakes in the family Viperidae, found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, New Zealand, Ireland, and various other isolated islands. They are venomous and have long (relative to non-vipe ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

. It is found in the

arid Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, increased temperatures, and limited water availability.Perez-Aguilar, L. Y., Plata ...

region of southwest

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

, in Angola, Botswana, Namibia; South Africa, and Zimbabwe. It is easily distinguished by the presence of a single, large horn-like scale over each eye. No

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

are currently recognized. Like all other vipers, it is

venomous Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

Common names

The species is commonly known as the horned adder,Spawls S, Branch B. 1995. ''The Dangerous Snakes of Africa''. Ralph Curtis Books. Dubai: Oriental Press. 192 pp. . horned puff adder,Mallow D, Ludwig D, Nilson G. 2003. ''True Vipers: Natural History and Toxinology of Old World Vipers''. Krieger Publishing Company, Malabar, Florida. 359 pp. . or horned viper.U.S. Navy. 1991. ''Poisonous Snakes of the World''. US Government. New York: Dover Publications Inc. 203 pp. .

Description

A short, stout little viper, it usually averages in total length (body + tail). The largest specimen reported being seen is a female from southern

Botswana Botswana, officially the Republic of Botswana, is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory part of the Kalahari Desert. It is bordered by South Africa to the sou ...

measuring total length.

Geographic range

The snake is found in far arid regions of southwest Africa: southwest

Angola Angola, officially the Republic of Angola, is a country on the west-Central Africa, central coast of Southern Africa. It is the second-largest Portuguese-speaking world, Portuguese-speaking (Lusophone) country in both total area and List of c ...

Namibia Namibia, officially the Republic of Namibia, is a country on the west coast of Southern Africa. Its borders include the Atlantic Ocean to the west, Angola and Zambia to the north, Botswana to the east and South Africa to the south; in the no ...

, across the

Kalahari Desert The Kalahari Desert is a large semiarid climate, semiarid sandy savanna in Southern Africa covering including much of Botswana as well as parts of Namibia and South Africa. It is not to be confused with the Angolan, Namibian, and South African ...

of southern

, into northern

Transvaal Transvaal is a historical geographic term associated with land north of (''i.e.'', beyond) the Vaal River in South Africa. A number of states and administrative divisions have carried the name ''Transvaal''. * South African Republic (1856–1902; ...

and southwestern

Zimbabwe file:Zimbabwe, relief map.jpg, upright=1.22, Zimbabwe, relief map Zimbabwe, officially the Republic of Zimbabwe, is a landlocked country in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Bots ...

. In

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

, it is found from the

Northern Cape The Northern Cape ( ; ; ) is the largest and most sparsely populated Provinces of South Africa, province of South Africa. It was created in 1994 when the Cape Province was split up. Its capital is Kimberley, South Africa, Kimberley. It includes ...

province south to the

Great Karoo The Karoo ( ; from the Afrikaans borrowing of the South Khoekhoe Khoemana (also known as !Orakobab or Korana) word is a semidesert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its extent i ...

. Its type locality is given as "... the sandy districts north of the Cape Colony..." outh Africa

Habitat

Horned adders are mostly found in sparsely vegetated

desert A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...

and semiarid scrub country.

Venom

Bites are assumed to be rare and no epidemiological data are available. Little information is available regarding the toxicity and amount of venom produced. Spawls and Branch (1995) reported an average yield of 85 mg of wet venom, while Christensen (1971) offered an value of 1.2 mg/kg IV.Brown JH. 1973. ''Toxicology and Pharmacology of Venoms from Poisonous Snakes''. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. . Other research has found the LD₅₀ to be between 0.15 and 0.22 mg/kg C Y Lee et al. 1982. "Site of action of caudoxin, a neurotoxic phospholipase A2 from the horned puff adder (Bitis caudalis) venom". Toxicon, 20(3), 637-647 Based on this LD₅₀ value, Spawls and Branch (1995) estimated about 300 mg of this venom would be required to kill an adult. They regarded this venom as one of the weakest of the genus, although 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) suggested it is highly toxic and a number of deaths have occurred as a result.U.S. Navy. 1965. ''Poisonous Snakes of the World''. US Government. Washington, District of Columbia: US Govt. Printing Office. 212 pp. 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. The National Antivenom and Vaccine Production Centre in

Riyadh Riyadh is the capital and largest city of Saudi Arabia. It is also the capital of the Riyadh Province and the centre of the Riyadh Governorate. Located on the eastern bank of Wadi Hanifa, the current form of the metropolis largely emerged in th ...

Saudi Arabia Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in West Asia. Located in the centre of the Middle East, it covers the bulk of the Arabian Peninsula and has a land area of about , making it the List of Asian countries ...

, produces a polyvalent antivenin that includes a paraspecific antibody that protects against bites from this species.''Bitis caudalis''
a
Munich AntiVenom INdex (MAVIN)
Accessed 21 April 2007. According to the U.S. Navy (1965, 1991), polyvalent antivenins produced by SAIMR and the

Pasteur Institute The Pasteur Institute (, ) is a French non-profit private foundation dedicated to the study of biology, micro-organisms, diseases, and vaccines. It is named after Louis Pasteur, who invented pasteurization and vaccines for anthrax and rabies. Th ...

are said to be effective, while Mallow et al. (2003) reported currently available antivenins are of limited effectiveness. Viljoen et al. (1982) isolated a protein, a

neurotoxic Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specifical ...

phospholipase A₂, from the venom, which they called "caudoxin". According to Lee et al. (1983), this is a

presynaptic In the nervous system, a synapse is a structure that allows a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or a target effector cell. Synapses can be classified as either chemical or electrical, depending o ...

toxin similar to bungarotoxin, but with different binding sites.

Taxonomy

A number of authors, including

Mertens __NOTOC__ Mertens () is a surname of Flanders, Flemish origin, meaning "son of Merten" (Martin (name), Martin). It is the fifth most common name in Belgium with 18,518 people in 2008. Geographical distribution As of 2014, 43.4% of all known bearer ...

(1955), use a trinomial to refer to this species, even though no subspecies are recognized.

References

External links

* . Accessed 1 March 2007. * . Accessed 1 March 2007. {{Taxonbar, from=Q1498639 Bitis Snakes of Africa Reptiles of Angola Reptiles of Botswana Reptiles of Namibia Reptiles of South Africa Reptiles of Zimbabwe Reptiles described in 1839 Taxa named by Andrew Smith (zoologist)