''Bitis'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

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 ...

s found in

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 ...

and the southern

Arabian Peninsula The Arabian Peninsula (, , or , , ) or Arabia, is a peninsula in West Asia, situated north-east of Africa on the Arabian plate. At , comparable in size to India, the Arabian Peninsula is the largest peninsula in the world. Geographically, the ...

. It includes the largest and the smallest vipers in the world. Members are known for their characteristic

threat displays Deimatic behaviour or startle display means any pattern of bluffing behaviour in an animal that lacks strong defences, such as suddenly displaying conspicuous eyespots, to scare off or momentarily distract a predator, thus giving the prey anima ...

that involve inflating and deflating their bodies while hissing and puffing loudly. The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

for this genus is '' B. arietans'', which is also the most widely distributed viper in Africa. Currently, 18

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), ...

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 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-viper ...

, 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 The canthus (: canthi, palpebral commissures) is either corner of the eye where the upper and lower eyelids meet. More specifically, the inner and outer canthi are, respectively, the medial and lateral ends/angles of the palpebral fissure. The ...

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 The rostral scale, or rostral, in snakes and other sca ...

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 In reptiles, the nasal scale refers to the scale that encloses the nostril. Mallow D, Ludwig D, Nilson G (2003). ''True Vipers: Natural History and Toxinology of Old World Vipers''. Malabar, Florida: Krieger Publishing Company. 359 pp. . Somet ...

. 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 Keeled Scales is an independent record label based in Austin, Texas. It was founded in 2014 by musicians Tony Presley (Real Live Tigers) and Seth Whaland (Literature, Tres Oui). The label has released over 60 albums from artists such as Buck Mee ...

that are imbricated (overlapping) with apical pits. At midbody, the

dorsal scales In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales. Campbell JA, Lamar WW (2004). ''The Venomous Reptiles of the Western Hemisphere''. Ithaca and London: Comstock Publis ...

number 21–46. Laterally, the dorsal scales may be slightly oblique. The

ventral scales In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that cont ...

, which number 112–153, are large, rounded, and sometimes have slight lateral keels. Their tails are short. The

anal scale In snakes, the anal scale or anal plate is the scale just in front of and covering the cloacal opening. This scale can be either single ("anal entire") or paired ("anal divided"). When paired, the division is oblique.Mallow D, Ludwig D, Nilson G ...

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 of the United States and Canada''. Comstock Publishing Associates, a Division of Cornell University Press. (7t ...

number 16-37 and are sometimes keeled laterally.

Geographic range

Puff adders are found in

and the southern

Behavior

''Bitis'' species are known for their behavior of inflating and deflating their bodies in loud hissing or puffing threat displays. They are

terrestrial Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on o ...

ambush predators, and appear sluggish, but can strike with amazing speed. In contrast to the pitvipers of the subfamily

Crotalinae The Crotalinae, commonly known as pit vipers,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . or pit adders, are a subfamily of vipers found in Asia and the Americas. Like all other vipers ...

, ''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 Rectilinear locomotion or rectilinear progression is a mode of animal locomotion, locomotion most often associated with snakes. In particular, it is associated with heavy-bodied species such as terrestrial African adders, Pythonidae, pythons and B ...

is very common in many ''Bitis'' species.

Reproduction

All members are

viviparous In animals, viviparity is development of the embryo inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives birth to a fully or partially developed juve ...

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
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 In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

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 In biology, a subgenus ( 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 the ge ...

: * ''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

External links

*
Southern adder (''Bitis armata'')
a
ARKive
Accessed 5 October 2006. {{Authority control Snake genera Taxa named by John Edward Gray Snakes of Arabia