Atheris

Atheris is a genus of vipers known as bush vipers.Spawls S, Branch B (1995). The Dangerous Snakes of Africa. Ralph Curtis Books. Dubai: Oriental Press. 192 pp. . They are found only in tropical subsaharan Africa (excluding southern Africa) and many species have isolated and fragmented distributions due to their confinement to rain forests.Mallow D, Ludwig D, Nilson G (2003). True Vipers: Natural History and Toxinology of Old World Vipers. Malabar, Florida: Krieger Publishing Company. 359 pp. . Like all other vipers, they are venomous. In an example of convergent evolution, they show many similarities to the arboreal pit vipers of Asia and South America. Seventeen species are currently recognized.

Description They are relatively small in size, with adults ranging in total length (body + tail) from for A. katangensis to a maximum of for A. squamigera.

All species have a broad, triangular head that is distinct from the neck. The canthus is also distinct and the snout is broad. The crown is covered with small imbricate or smooth scales, none of which is enlarged. The eyes are relatively large with elliptical pupils. The eyes are separated from the supralabials by 1–3 scale rows and from the nasal by 2–3 scales.

The body is slender, tapering, and slightly compressed. The dorsal scales are overlapping, strongly keeled and have apical pits. Laterally these are smaller than the middorsals. Midbody there are 14–36 rows of dorsal scales. There are 133–175 rounded ventral scales. The subcaudal scales are single and number 38–67. The tail is strongly prehensile and can support the body while suspended from a branch or a twig.Mehrtens JM (1987). Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. .

Members of this genus come in a wide variety of colors and patterns, often within a single species. A. Ceratophora and A. Squamigera are particularly variable.

Location They inhabit rainforest regions and forests, mostly in remote areas far from human activity.

They are found in tropical subsaharan Africa, excluding southern Africa. Some species have only isolated populations, surviving in small sections of ancient rainforest. They once had a much wider distribution but are now declining.

Conservation status Some species are threatened by habitat destruction. A major cause of illness and mortality in both caged and wild bush viper snakes is snake fungal disease.

Behavior All species have extreme aggressive tendencies. All species are arboreal, although they can sometimes be found on or near the ground.

Atheris species have been known to prey upon a variety of small amphibians, lizards, rodents, birds, and even other snakes. Some species or populations may specialize in eating frogs, but most have been described as opportunistic feeders. Prey is typically ambushed from a hanging position, held until it has succumbed to the venom, and then swallowed.

All Atheris species are ovoviviparous. Mating takes place in October and November, and the females give birth to live young in March and April.

Captivity A. squamigera is reported to do very well in captivity, needing only arboreal access and having no particular temperature requirements. Captive specimens take mice and small birds. However, there have been reports of cannibalism. Food may be refused during the African winter months of July and August.

Venom Limited understanding exists about their venom, except that it is strongly hemotoxic, causing pain, swelling, and blood clotting problems. Until recently, their venom has often been regarded as less toxic than that of many other species, perhaps because bites are uncommon, but this turned out not to be the case. There are now a number of reports of bites that have led to severe hemorrhaging.Bitten by a Sedge Viper! at VenomousReptiles.org . Accessed 2 August 2007. A case of a bite from A. nitschei caused local tissue injury, hemolysis, thrombocytopenia, hypofibrinoginemia, coagulopathy, and increased elevation in D-dimer. Envenomation cases from A. chlorechis and A. squamigera have shown similar symptoms. One case was fatal. Atheris-specific antivenom does not exist and antivenom meant for bites from other species seems to have little effect, although Echis antivenom has been reported to have been of some help in a case of A. squamigera envenomation. Symptomatic treatment is all that can be administered due to the absence of an Atheris-specific antivenom.

Species

Image Species Taxon author Subsp.* Common name Geographic rangeA. acuminataBroadley, 19980Acuminate bush viperWestern UgandaA. anisolepisMocquard, 18870Mayombe bush viperWest central Africa: Gabon, Congo, west DR Congo, north AngolaA. barbouri(Loveridge, 1930)0Barbour's short-headed viper, Uzungwe Mountain bush viperThe Udzungwa and Ukinga mountains in southern TanzaniaA. broadleyiD. Lawson, 19990Broadley's bush viperBeolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. . (Atheris broadleyi, p. 39).Cameroon, Central African Republic, Nigeria, CongoA. ceratophoraF. Werner, 18950Usambara eyelash viperThe Usambara and Uzungwe Mountains in TanzaniaA. chlorechisT(Pel, 1851)0West African bush viperWest Africa including Guinea-Bissau, Guinea, Sierra Leone, Liberia, Ivory Coast, Ghana, Togo, Benin, isolated locations in Nigeria, Cameroon, Equatorial Guinea, and GabonA. desaixiAshe, 19680Mount Kenya bush viper, Ashe's bush viperTwo isolated populations in Kenya: in the forests at Chuka, south-eastern Mount Kenya, and Igembe in the northern Nyambeni rangeA. hetfieldi Ceríaco, Marques & Bauer, 20200Hetfield’s bush viper Bioko island, Equatorial GuineaA. hirsutaR. Ernst & Rödel, 20020Tai hairy bush viperIvory CoastA. hispidaLaurent, 19550African hairy bush viperCentral Africa: DR Congo, south-west Uganda, west KenyaA. katangensisde Witte, 19530Katanga mountain bush viperRestricted to Upemba National Park, Shaba Province in eastern DR CongoA. mabuensisBranch & Bayliss, 20090Mount Mabu forest viperMount Mabu and Mount Namuli, northern MozambiqueA. matildaeMenegon, Davenport & Howell, 20110Matilda's horned vipersouth west TanzaniaA. mongoensisCollet & J.-F. Trape, 20200Mongo hairy bush viperDemocratic Republic of CongoA. nitscheiTornier, 19020Great Lakes bush viperCentral Africa from east DR Congo, Uganda and west Tanzania southward to north Malawi and north Zambia.A. rungweensisBogert, 1940 0Mt. Rungwe bush viper southwestern Tanzania, northeastern Zambia, northern MalawiA. squamigera(Hallowell, 1856)0Variable bush viperWest and central Africa: Ivory Coast and Ghana, eastward through southern Nigeria to Cameroon, southern Central African Republic, Gabon, Congo, DR Congo, northern Angola, Uganda, Tanzania (Rumanika Game Reserve), western Kenya, and Bioko IslandA. subocularisFischer, 18880Cameroon (Not including the nominate subspeciesT) Type species

Taxonomy Other species may be encountered in literature, such as:

Until relatively recently, the following species, all of which are terrestrial, were also included in the genus Atheris:

Montatheris hindii (Boulenger, 1910) – montane viper Proatheris superciliaris (W. Peters, 1855) – lowland viper

Together with Atheris, these three genera are sometimes referred to as the tribe Atherini.

References

Atheris

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