Bitis nasicornis is a viperspecies belonging to the genus Bitis, part of a subfamily known as "puff-adders",[3] found in the forests of West and Central Africa.[1][2][4] This large viper is known for its striking coloration and prominent nasal "horns".[5] No subspecies are currently recognized.[4][6] Its common names include butterfly viper, rhinoceros viper, river jack and many more (see section: common names).[7][5] Like all other vipers, it is venomous.
Its common and historical names include butterfly viper, rhinoceros viper, river jack,[7][5]rhinoceros horned viper, horned puff adder[8][3] and rhinoceros puff adder.[9]Americo-Liberians apparently call adult "puff-adders", such as the B. nasicornis, but also the B. gabonica (gaboon viper), cassava snakes.[3]
Historically this species was referred to as the rhinoceros viper (for example German: Nashornviper, French: Vipère rhinocéros) but this introduced confusion after the reclassification of the closely related species Bitis rhinoceros. The common name butterfly viper is therefore more distinct and preferred to avoid confusion.
The name "horned puff adder" (in relation to the viper subfamily "puff adders", today synonumous with the genus Bitis) is also a historical name for Bitis caudalis (horned adder)[7] and can cause confusion. Interestingly the dutch name for Bitis nasicornis is "rhinoceros puff adder" (Dutch: neushoornpofadder), while Bitis caudalis (horned adder) is named "horned puff adder" (Dutch: gehoornde pofadder).
Description
Detail of head
Large and stout,[10] it ranges in total length (body + tail) from 72 to 107cm (about 28 to 42 inches).[7] Spawls et al. (2004) mentioned a maximum total length of 120cm (47in), but admitted this is exceptional, quoting an average total length of 60–90cm (about 24–35 inches).[10] Explorer Harry Johnston (1858 – 1927) mentions in his book 'Liberia' (1906) that adult "puff-adders" of the species B. nasicornis and B. gabonica (gaboon viper) grow to "between four and five feet" (about 120 to 150 cm) in Liberia.[3] He also states that: "in case of the horned puff-adder, the young when born are a foot long" (~30 cm),[3] which is 20 to 65 percent longer than the average birth length given by Spawls et al. (2004): 18–25cm (7–10in).[10] Females grow larger than males.[11]
The head is narrow, flat, triangular and relatively small compared to the rest of the body.[7] The neck is thin. It has a distinctive set of two or three horn-like scales on the end of the nose, the front pair of which may be quite long. The eyes are small and set well forward.[10] The fangs are not large: rarely more than 1.5cm (0.59in) long.[7]
Midbody there are 31–43 dorsal scale rows.[7] These are so rough and heavily keeled that they sometimes inflict cuts on handlers when the snakes struggle.[5] There are 117–140 ventral scales[7] and the anal scale is single.[10] Mallow et al. (2003) reported the subcaudals number 16–32, with males having a higher count (25–30) than females (16–19).[7] Spawls et al. (2004) stated there are 12–32 subcaudals, paired, and males have the higher numbers of them.[10]
The color pattern consists of a series of 15–18 blue or blue-green, oblong markings, each with a lemon-yellow line down the center. These are enclosed within irregular, black, rhombic blotches. A series of dark crimson triangles run down the flanks, narrowly bordered with green or blue. Many of the lateral scales have white tips, giving the snake a velvety appearance. The top of the head is blue or green, overlaid with a distinct black arrow mark. The belly is dull green to dirty white, strongly marbled and blotched in black and gray.[10] Western specimens are more blue, while those from the east are more green. After they shed their skins, the bright colors fade quickly as silt from their generally moist habitat accumulates on the rough scales.[7]
It mainly occurs in forested areas, rarely venturing into woodlands. Its range is therefore more restricted than B. gabonica.[5]
Behavior
Primarily nocturnal, they hide during the day in leaf litter, in holes, around fallen trees or tangled roots of forest trees. Their vivid coloration actually gives them excellent camouflage in the dappled light conditions of the forest floor, making them almost invisible.[7] Although mainly terrestrial, they are also known to climb into trees and thickets, where they have been found up to 3m (9.8ft) above the ground.[5] This climbing behavior is aided by a partially prehensile tail.[7] They are sometimes found in shallow pools and have been described as powerful swimmers.[7][5]
They are slow moving, but capable of striking quickly, forwards or sideways, without coiling first or giving a warning. Holding them by the tail is not safe; as it is somewhat prehensile, they can use it to fling themselves upwards and strike.[7]
They have been described as generally placid creatures, less so than B. gabonica, but not as bad-tempered as B. arietans. When approached, they often reveal their presence by hissing,[7] said to be the loudest hiss of any African snake—almost a shriek.[10] These adders also make a sort of hissing noise through their nose as part of their respiratory function.
Two B. nasicornis hidden under tree root
Fully adult B. nasicornis resting flattened at Cincinnati Zoo, USA
B. nasicornis held captive with a Gaboon Viper (Bitis gabonica)
Feeding
Preferring to hunt by ambush, it probably spends much of its life motionless, waiting for prey to wander by.[10] Froesch (1967) described a captive specimen that would hardly ever leave its hide box, even when hungry, and once waited for three days for a live mouse to enter its hide box before striking. Feeding mainly on small mammals, but in wetlandhabitats, it is also known to take toads, frogs and even fish. One long-term captive specimen, regularly fed killed mice and frogs, always held on to its prey for several minutes after a strike before swallowing. It generally feeds on smaller prey than the closely related Gaboon viper (Bitis gabonica).[7]
Like most vipers, Bitis nasicornis are viviparous (producing their young alive).[3] In West Africa, the species gives birth to between six and 38 young in March–April at the beginning of the rainy season. Each neonate is 18–25cm (7–10in)[10] to a 1 foot (0.30m)[3] in total length when born. In eastern Africa, the breeding season is indefinite.[5]
Venom
Small doses of the snake's primarily hemotoxicvenom can be deadly. This is unlike the Gaboon viper, which uses a considerably larger amount of venom. Bitis nasicornis has both neurotoxic, as well as hemotoxic venom, as do most other venomous snakes. The hemotoxic venom in rhinoceros vipers is much more dominant. This venom attacks the circulatory system of the snake's victim, destroying tissue and blood vessels. Internal bleeding also occurs.
When not in use, the rhino viper's fangs are folded up into the roof of the snake's mouth. The snake has the ability to control the movement of its fangs. When a rhino viper opens its mouth, it does not necessarily mean that the fangs will flip down into place. The fangs penetrate deep into the victim and the venom flows through the hollow fangs into the wound.
Because of its restricted geographic range, few bites have been reported. No statistics are available.[5]
Relatively little is known about the toxicity and composition of the venom. In mice, the intravenous LD50 is 1.1mg/kg. The venom is supposedly slightly less toxic than those of B. arietans and B. gabonica. The maximum wet venom yield is 200mg.[5] One study reported this venom has the highest intramuscular LD50 value—8.6mg/kg—of five different viperid venoms tested (B. arietans, B. gabonica, B. nasicornis, Daboia russelii and Vipera aspis). Another showed little variation in the venom potency of these snakes, whether they were milked once every two days or once every three weeks. In rabbits, the venom is apparently slightly more toxic than that of B. gabonica.[7]
In only a few detailed reports of human envenomation, massive swelling, which may lead to necrosis, had been described.[5] In 2003, a man in Dayton, Ohio, who was keeping a specimen as a pet, was bitten and subsequently died.[12] At least one antivenom protects specifically against bites from this species: India Antiserum Africa Polyvalent.[13]
Related Research Articles
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 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.
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.
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.
Horned puff adder may refer to:
The many-horned adder is a viper species. It is found in certain rocky desert areas, mostly along the Atlantic coast of southern Africa, in western South Africa and southwestern Namibia. It has characteristic tufts of "horns" above each eye. Like all other vipers, it is venomous. No subspecies are currently recognized.
The Albany adder is a viper species. It was previously considered a subspecies of Bitis cornuta. Its range is restricted to eastern and southern Cape Province in South Africa. Like all vipers, it is venomous.
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 worthingtoni, also known commonly as the Kenya horned viper and the Kenyan horned viper, is a species of venomous snake in the subfamily Viperinae of the family Viperidae. The species is endemic to Kenya. There are no subspecies that are recognized as being valid.
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".
Bitis harenna, or the Bale Mountains adder, is a relatively unknown species of viper from and named after the Harenna Forest in the Oromia Region of Ethiopia. It is often mixed up with the Bitis parviocula in multiple scientific papers, as both it and B. parviocula lack horns between nostrils, as well as sharing specific numbers of specific scales and a pale 'cross bar' marking on the head behind the eyes. However, it can be told apart from all other Macrocerastes species by their unique colouring, markings and braincase. The species has only been officially sighted at a length of 66cm to 1m.
1 2 3 4 McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Herpetologists' League. 511 pp. ISBN1-893777-00-6 (series). ISBN1-893777-01-4 (volume).
↑ U.S. Navy. 1991. Poisonous Snakes of the World. US Govt. New York: Dover Publications Inc. 203 pp. ISBN0-486-26629-X.
↑ Johnston, Harry (1906). "Chapter XXV, Fauna: reptiles, amphibians, and fish". Liberia(PDF). London: Hutchinson & Co. p.809. ISBN1166209008. Retrieved 2023-05-09. black and white illustration no. 306: Examples of the principal poisonous snakes of Liberia, (Rhinoceros puff-adder)
1 2 3 4 5 6 7 8 9 10 Spawls S, Howell K, Drewes R, Ashe J. 2004. A Field Guide to the Reptiles of East Africa. London: A & C Black Publishers Ltd. 543 pp. ISBN0-7136-6817-2.
↑ Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN0-8069-6460-X.
Boulenger GA. 1896. Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the...Viperidæ. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers.) xiv + 727 pp. + Plates I.- XXV. (Bitis nasicornis, pp.500–501.)
Froesch VP. 1967. Bitis nasicornis, ein Problem-Pflegling? Aquar. U. Terrar. Z. 20: 186–189.
Shaw G. 1792. The Naturalist's Miscellany. Volume III. London: F.P. Nodder & Co. (Coluber nasicornis, Plate XCIV.)
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