Bitis | |
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Bitis arietans | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | Squamata |
Suborder: | Serpentes |
Family: | Viperidae |
Subfamily: | Viperinae |
Genus: | Bitis Gray, 1842 |
Synonyms [1] | |
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Bitis is a genus of vipers found in Africa and the southern Arabian Peninsula. [1] 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. [2] The type species for this genus is B. arietans , [1] which is also the most widely distributed viper in Africa. [3] Currently, 18 species are recognized. [4]
Members of the genus are commonly known as African adders, [2] African vipers, [3] or puff adders.
Size variation within this genus is extreme, ranging from the very small B. schneideri , which grows to a maximum of 28 cm (11 in) and is perhaps the world's smallest viperid, to the very large B. gabonica , which can attain a length over 2 m (6.6 ft) and is the heaviest viper in the world. [2]
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. [2] [5]
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. [2] [5]
Puff adders are found in Africa and the southern Arabian Peninsula. [1]
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. [2] 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. [6] [7]
The rectilinear locomotion is very common in many Bitis species.
All members are viviparous and some give birth to large numbers of offspring. [2]
All members of this genus are dangerous— some extremely so. [2] 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 . [8] [9] At least one protects specifically against bites from B. nasicornis : India Antiserum Africa Polyvalent. [10] In the past, such antivenoms have been used to treat bites from other Bitis species, but with mixed results. [2]
Image | Species [1] | Taxon author [1] | Subsp.* [4] | Common name | Geographic range [1] |
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B. albanica | Hewitt, 1937 | 0 | Albany adder | Republic of South Africa, Eastern Cape Province from Port Elizabeth to near Committees. | |
B. arietans T | (Merrem, 1820) | 1 | Puff adder | Most 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 Yemen | |
B. armata | (A. Smith, 1826) | 0 | Southern adder | Republic of South Africa, Southwestern Western Cape, from West Coast National Park to De Hoop Nature Reserve | |
B. atropos | (Linnaeus, 1758) | 0 | Berg adder | Isolated 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 Province | |
B. caudalis | (A. Smith, 1839) | 0 | Horned adder | The 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 Karoo | |
B. cornuta | (Daudin, 1803) | 0 | Many-horned adder | The coastal region of southwest Namibia through west and southwest Cape Province in South Africa, with a few isolated populations in eastern Cape Province | |
B. gabonica | (A.M.C. Duméril, Bibron & A.H.A. Duméril, 1854) | 0 | Gaboon viper | Guinea, 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 Africa | |
B. harenna | Gower, Wade, Spawls, Böhme, Buechley, Sykes, & Colston, 2016 | 0 | Bale Mountains adder | Ethiopia | |
B. heraldica | (Bocage, 1889) | 0 | Angolan adder | The high plateau of central Angola | |
B. inornata | (A. Smith, 1838) | 0 | Plain mountain adder | Isolated population on the Sneeuberge, eastern Cape Province, South Africa | |
B. nasicornis | (Shaw, 1792) | 0 | Rhinoceros viper | From 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 Kenya | |
B. parviocula | Böhme, 1977 | 0 | Ethiopian mountain adder | Known from only five localities in the highlands to southwest Ethiopia, at altitudes of 1700–2800 m. [11] | |
B. peringueyi | (Boulenger, 1888) | 0 | Peringuey's desert adder | The Namib Desert from southern Angola to Lüderitz, Namibia | |
B. rhinoceros | (Schlegel, 1855) | 0 | West African Gaboon viper | Guinea, Guinea-Bissau, Liberia, Sierra Leone, Ivory Coast, Ghana, Togo | |
B. rubida | Branch, 1997 | 0 | Red adder | Several isolated populations in the northern Cape Fold Mountains and inland escarpment in Western Cape Province, South Africa | |
B. schneideri | (Boettger, 1886) | 0 | Namaqua dwarf adder | White coastal sand dunes from Namibia, near Lüderitz, south to Hondeklip Bay, Little Namaqualand, South Africa | |
B. worthingtoni | Parker, 1932 | 0 | Kenya horned viper | Restricted to Kenya's high central Rift Valley at altitudes over 1500 m | |
B. xeropaga | Haacke, 1975 | 0 | Desert mountain adder | Northwestern 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.
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: [2]
Viperinae, or viperines, are a subfamily of vipers endemic to Europe, Asia and Africa. They are distinguished by their lack of the heat-sensing pit organs that characterize their sister group, the subfamily Crotalinae. Currently, 13 genera are recognized. Most are tropical and subtropical, although one species, Vipera berus, even occurs within the Arctic Circle. Like all vipers, they are venomous.
Keeled scales refer to reptile scales that, rather than being smooth, have a ridge down the center that may or may not extend to the tip of the scale, making them rough to the touch. According to Street's (1979) description of European lizards and snakes, in those that have keeled scales the keels are usually stronger in male specimens and are consistently arranged according to the species of reptiles, even though many others do not have them. With European lizards, the dorsal scales are usually well keeled, while those on the flanks are more weakly keeled and those on the belly smooth. Non-European lizards such as Sphaerodactylus macrolepis also display keeled scales.
The Gaboon viper, also called the Gaboon adder, is a large and highly venomous viper species found in the rainforests and savannas of sub-Saharan Africa. Like all other vipers, it is venomous. It is the largest member of the genus Bitis, and has the longest fangs of any venomous snake – up to 2 inches (5.1 cm) in length – and the highest venom yield of any snake. No subspecies are recognized.
Bitis nasicornis is a viper species belonging to the genus Bitis, part of a subfamily known as "puff-adders", found in the forests of West and Central Africa. This large viper is known for its striking coloration and prominent nasal "horns". No subspecies are currently recognized. Its common names include butterfly viper, rhinoceros viper, river jack and many more. Like all other vipers, it is venomous.
The puff adder is a highly venomous viper species found in savannahs and grasslands from Morocco and western Arabia throughout Africa except for the Sahara and rainforest regions. It is responsible for causing the most snakebite fatalities in Africa owing to various factors, such as its wide distribution, frequent occurrence in highly populated regions, and aggressive disposition. Like all other vipers, it is venomous. Two subspecies are currently recognized, including the nominate subspecies described here.
Hypnale is a genus of pit vipers endemic to Sri Lanka and southwestern India. Three monotypic species are currently recognized. All members have more or less upturned snouts that produce a hump-nosed effect.
Ovophis monticola, commonly known as the Chinese mountain pit viper, is a pit viper species found in Asia. Currently, two subspecies are recognized, including the nominate subspecies described here. Recent taxonomic work suggests that most of these should be considered as separate species. IUCN has already evaluated O. m. makazayazaya as Ovophis makazayazaya.
Trimeresurus albolabris, the white-lipped pit viper or white-lipped tree viper, is a venomous pit viper species endemic to Southeast Asia.
Causus is a genus of vipers found only in sub-Saharan Africa. It is a group considered to be among the most primitive members of the family Viperidae based on head scalation, oviparity, venom apparatus, and because they have round pupils. However, this is contradicted by recent molecular studies. Seven species are currently recognized. They are commonly known as night adders. Like all other vipers, they are venomous.
Bitis arietans somalica also known as the Somali puff adder, is a venomous viper subspecies found only in Somalia, eastern Ethiopia, and northern Kenya. It is distinguished from B. a. arietans by its keeled subcaudals.
The berg adder is a viper species endemic to mountainous regions in southern Africa. No subspecies are currently recognized.
The horned adder is a viper species. It is found in the arid region of southwest Africa, 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 are currently recognized. Like all other vipers, it is venomous.
Bitis schneideri is a species of venomous snake in the subfamily Viperinae of the family Viperidae. The species is native to a small coastal region that straddles the border between Namibia and South Africa. B. schneideri is the smallest species in the genus Bitis and possibly the world's smallest viper. There are no subspecies that are currently recognized as being valid.
Bitis inornata is a venomous viper species found only in Cape Province, South Africa. No subspecies are currently recognized.
Bitis parviocula is a venomous viper species found only in Ethiopia. It is large with a broad head and spectacular geometric markings. In 1995, the species was known from only three specimens, but additional information has surfaced since then. Little is known about its natural history or its venom. No subspecies are currently recognized.
Bitis peringueyi, also known as the Peringuey's adder, Peringuey's desert adder or desert sidewinding adder, is a viper species found in Namibia and southern Angola. No subspecies are currently recognized.
Bitis rhinoceros is a viper species endemic to West Africa. Like all vipers, it is venomous. It can be easily distinguished from the closely related species B. gabonica by the presence of two large nasal "horns".
Echis pyramidum, known as the Northeast African carpet viper, Egyptian saw-scaled viper, and by other common names, is a species of viper endemic to Northeast Africa and the Arabian Peninsula. Like all other vipers, it is venomous. Three subspecies are currently recognized, including the nominate subspecies described here.