Bitis

Bitis is a genus of vipers found in Africa and the southern Arabian Peninsula. It includes the largest and the smallest vipers in the world. Members are known for their characteristic threat displays that involve inflating and deflating their bodies while hissing and puffing loudly. The type species for this genus is B. arietans, which is also the most widely distributed viper in Africa. Currently, 18 species are recognized.

Members of the genus are commonly known as African adders,Mallow D, Ludwig D, Nilson G. 2003. True Vipers: Natural History and Toxinology of Old World Vipers. Malabar, Florida: Krieger Publishing Company. 359 pp. . African vipers,Spawls S, Branch B. 1995. The Dangerous Snakes of Africa. Dubai: Ralph Curtis Books. Oriental Press. 192 pp. . or puff adders.

Description Size variation within this genus is extreme, ranging from the very small B. schneideri, which grows to a maximum of and is perhaps the world's smallest viperid, to the very large B. gabonica, which can attain a length over and is the heaviest viper in the world.

All have a wide, triangular head with a rounded snout, distinct from the neck, and covered in small, keeled, imbricated scales. The canthus is also distinct. A number of species have enlarged rostral or supraorbital scales that resemble horns. Their eyes are relatively small. They have large nostrils that are directed outwards and/or upwards. Up to six rows of small scales separate the rostral and nasal scales. All species have a well-developed supranasal sac. The fronts of the maxillary bones are very short, supporting only one pair of recurved fangs.U.S. Navy. 1965. Poisonous Snakes of the World. Washington, District of Columbia: United States Government Printing Office. 212 pp.

These snakes are moderately to extremely stout. Their bodies are covered with keeled scales that are imbricated (overlapping) with apical pits. At midbody, the dorsal scales number 21–46. Laterally, the dorsal scales may be slightly oblique. The ventral scales, which number 112–153, are large, rounded, and sometimes have slight lateral keels. Their tails are short. The anal scale is single. The paired subcaudal scales number 16-37 and are sometimes keeled laterally.

Geographic range Puff adders are found in Africa and the southern Arabian Peninsula.

Behavior Bitis species are known for their behavior of inflating and deflating their bodies in loud hissing or puffing threat displays. They are terrestrial ambush predators, and appear sluggish, but can strike with amazing speed. In contrast to the pitvipers of the subfamily Crotalinae, Bitis species appear to lack heat-sensitive organs and showed no differences in their behavior in laboratory tests towards warm and cool objects that mimicked prey.

The rectilinear locomotion is very common in many Bitis species.

Reproduction All members are viviparous and some give birth to large numbers of offspring.

Venom All members of this genus are dangerous⁠some extremely so. At least six different polyvalent antivenoms are available. Five are produced by Aventis Pasteur (France), Pasteur Merieux (France) and SAIMR (South Africa). All of these specifically protect against B. arietans and four also cover B. gabonica.Bitis arietans antivenoms at Munich AntiVenom INdex. Accessed 25 August 2006.Bitis gabonica antivenoms at Munich AntiVenom INdex. Accessed 25 August 2006. At least one protects specifically against bites from B. nasicornis: India Antiserum Africa Polyvalent.Miami-Dade Fire Rescue Venom Response Unit at VenomousReptiles.org . Accessed 5 September 2006. In the past, such antivenoms have been used to treat bites from other Bitis species, but with mixed results.

Species Image Species Taxon author Subsp.* Common name Geographic rangeB. albanicaHewitt, 19370Albany adderRepublic of South Africa, Eastern Cape Province from Port Elizabeth to near Committees.B. arietansT(Merrem, 1820)1Puff adderMost of sub-Saharan Africa south to the Cape of Good Hope, including southern Morocco, Mauritania, Senegal, Mali, southern Algeria, Guinea, Sierra Leone, Ivory Coast, Ghana, Togo, Benin, Niger, Nigeria, Chad, Sudan, Cameroon, Central African Republic, northern, eastern and southern Democratic Republic of the Congo, Uganda, Kenya, Somalia, Rwanda, Burundi, Tanzania, Angola, Zambia, Malawi, Mozambique, Zimbabwe, Botswana, Namibia, South Africa, also occurs on the Arabian peninsula, where it is found in southwestern Saudi Arabia and YemenB. armata(A. Smith, 1826)0Southern adderRepublic of South Africa, Southwestern Western Cape, from West Coast National Park to De Hoop Nature ReserveB. atropos(Linnaeus, 1758)0Berg adderIsolated populations in the mountainous areas of southern Africa: the Inyanga Highlands and Chimanimani Mountains of eastern Zimbabwe and nearby Mozambique, in South Africa along the Drakensberg Escarpments in the provinces of Transvaal, western Natal, Lesotho and eastern Free State, and in the southern coastal mountains of western and eastern Cape ProvinceB. caudalis(A. Smith, 1839)0Horned adderThe arid region of southwest Africa: southwest Angola, Namibia, across the Kalahari Desert of southern Botswana, into northern Transvaal and southwestern Zimbabwe, in South Africa from the northern Cape Province south to the Great KarooB. cornuta(Daudin, 1803)0Many-horned adderThe coastal region of southwest Namibia through west and southwest Cape Province in South Africa, with a few isolated populations in eastern Cape ProvinceB. gabonica(A.M.C. Duméril, Bibron & A.H.A. Duméril, 1854)0Gaboon viperGuinea, Ghana, Togo, Nigeria, Cameroon, DR Congo, Central African Republic, southern Sudan, Uganda, Kenya, eastern Tanzania, Zambia, Malawi, eastern Zimbabwe, Mozambique, northeast KwaZulu-Natal Province in South AfricaB. harennaGower, Wade, Spawls, Böhme, Buechley, Sykes, & Colston, 20160Bale Mountains adder EthiopiaB. heraldica(Bocage, 1889)0Angolan adderThe high plateau of central AngolaB. inornata(A. Smith, 1838)0Plain mountain adderIsolated population on the Sneeuberge, eastern Cape Province, South AfricaB. nasicornis(Shaw, 1792)0Rhinoceros viperFrom Guinea to Ghana in West Africa, and in Central Africa in the Central African Republic, southern Sudan, Cameroon, Gabon, Congo, DR Congo, Angola, Rwanda, Uganda and western KenyaB. parvioculaBöhme, 19770Ethiopian mountain adderKnown from only five localities in the highlands to southwest Ethiopia, at altitudes of 1700–2800 m.Largen, M., and Spawls, S. 2010. The Amphibians and Reptiles of Ethiopia and Eritrea. Frankfurt am Main: Edition Chimara. B. peringueyi(Boulenger, 1888)0Peringuey's desert adderThe Namib Desert from southern Angola to Lüderitz, NamibiaB. rhinoceros(Schlegel, 1855)0West African Gaboon viperGuinea, Guinea-Bissau, Liberia, Sierra Leone, Ivory Coast, Ghana, TogoB. rubidaBranch, 19970Red adderSeveral isolated populations in the northern Cape Fold Mountains and inland escarpment in Western Cape Province, South AfricaB. schneideri(Boettger, 1886)0Namaqua dwarf adderWhite coastal sand dunes from Namibia, near Lüderitz, south to Hondeklip Bay, Little Namaqualand, South AfricaB. worthingtoniParker, 19320Kenya horned viperRestricted to Kenya's high central Rift Valley at altitudes over 1500 mB. xeropagaHaacke, 19750Desert mountain adderNorthwestern Cape Province in South Africa and the arid mountains of the lower Orange River basin, north into southern Namibia and Great Namaqualand as far as Aus *) Not including the nominate subspecies. T) Type species.

Taxonomy Lenk et al. (1999) used molecular data (immunological distances and mitochondrial DNA sequences) to estimate the phylogenetic relationships among species of Bitis. They identified four major monophyletic groups for which they created four subgenera:

Bitis – B. arietans Calechidna – B. albanica, B. armata, B. atropos, B. caudalis, B. cornuta, B. heraldica, B. inorata, B. peringueyi, B. rubida, B. schneideri, B. xeropaga Macrocerastes – B. gabonica, B. nasicornis, B. parviocula Keniabitis – B. worthingtoni

References

Bitis

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