Rhinoceros Viper

Bitis nasicornis is a viper species belonging to the genus Bitis, part of a subfamily known as "puff-adders", 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, river jack and many more (see section: common names). Like all other vipers, it is venomous.

Common names

Its common and historical names include butterfly viper, rhinoceros viper, river jack, rhinoceros horned viper, horned puff adder and rhinoceros puff adder. Americo-Liberians apparently call adult "puff-adders", such as the B. nasicornis, but also the B. gabonica (gaboon viper), cassava snakes.

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 synonymous with the genus Bitis) is also a historical name for Bitis caudalis (horned adder) 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

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). 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. He also states that: "in case of the horned puff-adder, the young when born are a foot long" (~30 cm), which is 20 to 65 percent longer than the average birth length given by Spawls et al. (2004): 18–25 cm (7–10 in). 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.