The puff adder (Bitis arietans) 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 species is commonly known as the puff adder, African puff adder, or common puff adder. Taxonomy German naturalist Blasius Merrem described the puff adder in 1820. The word arietans means "striking violently" and is derived from the Latin arieto. The type locality given is "Promontorio bonae spei" (Cape of Good Hope), South Africa. Subspecies Description The snake's typical size is about 1.0 m (39.3 in) in total length (body and tail) and very stout. Large specimens of 190 cm (75 in) total length, weighing over 6.0 kg (13.2 lb) and with a girth of 40 cm (16 in) have been reported. Specimens from Saudi Arabia are not as large, usually no more than in total length. Males are usually larger than females and have relatively longer tails. The color pattern varies geographically. The head has two well-marked dark bands - one on the crown and the other between the eyes. On the sides of the head, two oblique, dark bands or bars run from the eye to the supralabials. Below, the head is yellowish white with scattered dark blotches. Iris color ranges from gold to silver-gray. Dorsally, the ground color varies from straw yellow, to light brown, to orange or reddish brown. This is overlaid with a pattern of 18–22 backwardly directed, dark brown to black bands that extend down the back and tail. Usually, these bands are roughly chevron-shaped, but may be more U-shaped in some areas. They also form two to six light-and-dark cross-bands on the tail. Some populations are heavily flecked with brown and black, often obscuring other coloration, giving the animal a dusty-brown or blackish appearance. The belly is yellow or white, with a few scattered dark spots. Newborn young have golden head markings with pinkish to reddish ventral plates toward the lateral edges. One unusual specimen, described by Branch and Farrell (1988), from Summer Pride, East London, in South Africa, was striped. The pattern consisted of a narrow (one