Fea's Viper

Azemiopinae is a monogeneric subfamily created for the genus Azemiops that contains the viper species A. feae and A. kharini. They are commonly known as Fea's vipers. No subspecies are recognized. The first specimen was collected by Italian explorer Leonardo Fea, and was described as a new genus and new species by Boulenger in 1888. Formerly considered to be one of the most primitive vipers, molecular studies have shown that it is the sister taxon to the pit vipers, Crotalinae. It is found in the mountains of Southeast Asia, in China, southeastern Tibet, and Vietnam. Like all other vipers, they are venomous.

Description

Neither species grows to 1 m in length. According to Liem et al. (1971), the maximum length is 77 cm, while Orlov (1997) described a male and a female measuring 72 cm and 78 cm, respectively.

It is considered to be the most primitive of all viperids for several reasons. It has a reasonably sturdy body and a short tail, but the dorsal scales are smooth rather than keeled like those of most vipers. The head, which is slightly flattened and more elliptical in shape than triangular, is not covered with numerous small scales like most other vipers, but with large shields like the colubrids and the elapids. Also, the skull is built differently. It does, however, have a pair of hollow, rotating fangs, although these are short. The fangs have a ridge at the tip lateral to the discharge orifice, as well as a blade-like structure on the ventral surface otherwise seen only in some opistoglyphous and atractaspid snakes. The venom glands are relatively small. Unlike most vipers, Fea's viper is oviparous and hibernates during the winter.

The color pattern of Fea's viper is striking; dorsally, its basic body color is a shiny, deep blue-gray to black, marked by several widely spaced, thin (one or two scales), white-orange crossbands. The head is orange to slightly yellow with a distinct cross-pattern outlined in gray. The eyes are yellowish with vertical pupils. Ventrally, it is olive-gray, with some small, lighter spots. The chin and throat are variegated with yellow.

The smooth dorsal scales are arranged in 17 rows at midbody. The anal plate is entire (undivided), but the subcaudals are in two rows (divided). The ventral count is around 180, and subcaudals around 40.

Internasals and prefrontals are subequal in length, which is between 0.7 and 1.0 mm. The frontal is slightly broader than long, nearly three times as broad as the supraocular. Parietals are as long as their distance from the end of the snout. The loreal scale is small, pentagonal, and as tall as long. Two (or three) preoculars and two postoculars are present, and two large superposed anterior temporals occur, but only the upper in contact with the postoculars. It has six upper labials. The first and second are smallest, the third enters the eye, and the fourth and fifth are largest. It has seven lower labials, the first is large and forms a suture with its fellow, and the second is small. It has one pair of short chin shields.

Geographic range