African puff adder

Bitis arietans is a venomous viper species found in savannah and grasslands from Morocco and western Arabia throughout Africa except for the Sahara and rain forest regions. It is responsible for causing the most fatalities in Africa owing to various factors, such as its wide distribution and frequent occurrence in highly populated regions. Two subspecies are currently recognized, including the nominate subspecies described here.

The species is commonly known as puff adder, African puff adder, or common puff adder.

The average size is about 1 m in length and very stout. Large specimens of 190 cm (75 in), weighing over 6.0 kg (13.2 lbs) and with a girth of 40 cm (16 in) have been reported. Specimens from Saudi Arabia are not as large, usually no more than 80 cm in length. Males are usually larger than females and have relatively longer tails. The head has a less than triangular shape with a blunt and rounded snout. Still, it is much wider than the neck. The rostral scale is small. The circumorbital ring consists of 10–16 scales. Across the top of the head, there are 7–11 interocular scales. 3–4 scales separate the suboculars and the supralabials. There are 12–17 supralabials and 13–17 sublabials. The first 3–4 sublabials contact the chin shields. Often, there are two fangs on each maxilla and both can be functional.

Midbody there are 29–41 rows of dorsal scales. These are strongly keeled except for the outermost rows. The ventral scale count is 123–147, the subcaudals 14–38. Females have no more than 24 subcaudals. The anal scale is single.

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, there are two oblique dark bands or bars that 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 2–6 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 (1 scale wide) pale yellowish stripe that ran from the crown of the head to the tip of the tail.
Generally, though, these are relatively dull-looking snakes, except for male specimens from highland east Africa and Cape Province, South Africa, that usually have a striking yellow and black color pattern.