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 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 it has the longest fangs of any venomous snake – up to 2 inches (5 cm) in length – and the highest venom yield of any snake. No subspecies are recognized.
Bitis is a genus of venomous 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.
Bitis nasicornis is a viper species 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, and river jack. Like all other vipers, it is venomous.
The puff adder is a 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.
The berg adder is a venomous 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.
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 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. scneideri 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 heraldica is a venomous viper species endemic to Angola. It is easily distinguished from B. caudalis by its heavily speckled belly and lack of any supraocular "horns". No subspecies are currently recognized.
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 venomous viper species found in Namibia and southern Angola. No subspecies are currently recognized.
The red adder is a viper species found only in Western Cape Province, South Africa. No subspecies are currently recognised. Like all other vipers, it is venomous.
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 Kenya. There are no subspecies that are recognized as being valid.
Bitis xeropaga, commonly known as the desert mountain adder or Lüderitz dwarf viper, is a viper species found in southern Namibia and northwestern Cape Province in South Africa. Like all other vipers, it is venomous. No subspecies are currently recognized.
Causus rhombeatus, commonly known as the rhombic night adder, is a viper species endemic to subsaharan Africa. No subspecies are currently recognized. Like all other vipers, it is venomous.
Causus resimus is a viper species found in isolated populations distributed across tropical Africa. No subspecies are currently recognized. Like all other vipers, it is venomous.
