Bitis nasicornis

Description

Bitis nasicornis is a venomous 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. Common names: butterfly viper, rhinoceros viper, river jack. Large and stout, it ranges in total length (body + tail) from 72 to 107 cm (about 28 to 42 inches). Spawls et al. (2004) mentioned a maximum total length of 120 cm (47 in), but admitted this is exceptional, quoting an average total length of 60-90 cm (about 24-35 inches). Females grow larger than males. The head is narrow, flat, triangular and relatively small compared to the rest of the body. 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. The fangs are not large: rarely more than 1.5 cm (0.59 in) long. Midbody there are 31-43 dorsal scale rows. These are so rough and heavily keeled that they sometimes inflict cuts on handlers when the snakes struggle. There are 117-140 ventral scales and the anal scale is single. Mallow et al. (2003) reported the subcaudals number 16-32, with males having a higher count (25-30) than females (16-19). Spawls et al. (2004) stated there are 12-32 subcaudals, paired, and males have the higher numbers of them. 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. 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.