Bitis Nasicornis2
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''Bitis'' is a genus of venomous vipers found in Africa and the southern
Arabian Peninsula The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs") or Arabia, is a peninsula of Western Asia, situated northeast of Africa on the Arabian Plate ...
. 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 Rostral may refer to: Anatomy * Rostral (anatomical term), situated toward the oral or nasal region * Rostral bone, in ceratopsian dinosaurs * Rostral organ, of certain fish * Rostral scale, in snakes and scaled reptiles Other uses * Rostral colu ...
or
supraorbital Supraorbital refers to the region immediately above the eye sockets, where in humans the eyebrows are located. It denotes several anatomical features, such as: *Supraorbital artery *Supraorbital foramen *Supraorbital gland *Supraorbital nerve *Sup ...
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 In snakes, the subcaudal scales are the enlarged plates on the underside of the tail.Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates (7th printing, 1985). 1105 pp. . These scales may be either single or divided (pair ...
number 16-37 and are sometimes keeled laterally.


Geographic range

Puff adders are found in Africa and the southern
Arabian Peninsula The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs") or Arabia, is a peninsula of Western Asia, situated northeast of Africa on the Arabian Plate ...
.


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.


Reproduction

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


Venom

All members of this genus are dangerous – some 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
a
Munich AntiVenom INdex
Accessed 25 August 2006.

a
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
a
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

''*) Not including the nominate subspecies.''
T'') Type species.


Taxonomy

Other species may be encountered in literature, such as: * ''B. albanica'' – Hewitt, 1937 * ''B. armata'' – Smith, 1826 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 In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
: * ''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'' For now, this division is of little consequence as far as the nomenclature is concerned. However, the definition of subgenera within a genus is often the sign of an impending split. Therefore, those interested in these snakes would do well to familiarize themselves with these new subgenera.


References


Further reading

* * Duméril A-M-C, Bibron G. 1844. ''Erpetologie Générale ou Histoire Naturelle Complete des Reptiles. Vol.6''. Paris: Librarie Encyclopédique de Roret. 609 pp. 0 * Gray JE. 1842. Monographic Synopsis of the Vipers, or the Family Viperidæ. ''Zoological Miscellany, London'' 2: 68–71. 9 * Laurenti J.N. 1768. ''Specimen medicum, exhibens synopsin reptilium emendatum cum experimentis circa venena et antidota reptilium Austriacorum''. Vienna: J.T. de Trattern. 214 pp. 03 * * Merrem B. 1820. ''Versuch eines Systems der Amphibien. Tentamen systematis amphibiorum''. Marburg: J.C. Krieger. xv + 191 pp. 50 1 pl. * Reuss T. 1939. "Berichtigungen und Ergänzungen zu meinen Arbeiten über Toxicophidier, 1938." ''Zeitschrift für Aquarien- und Terrarien-Vereine, Berlin'' (1), 13–14 4 * U.S. Navy. 1991. ''Poisonous Snakes of the World''. New York: Dover Books. (Reprint of US Govt. Printing Office, Washington D.C.) 232 pp. .


External links

*
Southern adder (''Bitis armata'')
a
ARKive
Accessed 5 October 2006. {{Taxonbar, from=Q574527 Snake genera Taxa named by John Edward Gray