Azemiopinae

Common names: Fea's viper.^[2]

Azemiopinae is a monotypic subfamily created for the monotypic genus, Azemiops, that contains the venomous viper species A. feae, described here. No subspecies are recognized.^[3] The first specimens were described by European explorer M.L. Fea, with the genus later being described by Boulenger in 1888.^[2] Considered to be one of the most primitive vipers,^[4] it is found in the mountains of South East Asia^[5] in China, toutheastern Tibet and Vietnam.^[2]

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Description

  This species does not grow to more than 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.^[2]

The Fea's viper is considered the most primitive of all viperids for a number of 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 hollow, rotating fangs, although these are short. The fangs have a ridge at the tip lateral to the discharge oriface, as well as a blade-like structure on the ventral surface seen only in some opistoglyphous and atractaspid snakes. The venom glands are relatively small. Finally, unlike most vipers, the Fea's viper is oviparous and hibernates during the winter months.^[2]

The color pattern of the Fea's viper is striking: its basic body color is a shiny, deep blue-gray to black and marked by a number of widely spaced thin (1-2 scales) white-orange bands. The head is orange to slightly yellow with a distinct cross-pattern outlined in gray. The eyes are yellowish with vertical pupils.^[2]

Geographic range

Ranges from northern Vietnam through southern China (Fujien, Guangxi, Jiangxi, Kweichow, Sichuan, Yunnan, Zhejiang), south-east, Myanmar and south-east Tibet. The type locality is listed as "Kakhien Hills (Kachin Hills), Myanmar."^[1]

Habitat

Found in mountainous regions at altitudes up to 1000 m. Cooler climates are preferred, with an average temperature of 20-25 °C. Sometimes it is found on roadsides, in straw and grass, in rice fields, and even in and around homes. In Vietnam, its preferred habitat is described as forests of bamboo and tree ferns, with clearings, where the forest floor is covered with rotting vegetation, where there are plenty of rock outcroppings and there are many open and subterranean streams. The species is nocturnal, prefers nighttime temperatures of 18-25 °C, very moist environments and hides in places that are absolutely wet.^[2]

Behavior

This species has a characteristic threat display. When disturbed, it flattens its body to make itself look wider, and its jaws flare outwards posteriorly to giving the normally ovoid head a triangular shape. Sometimes, it will vibrate its tail. Ultimately, it will strike, during which it may or may not use its fangs. As opposed to Orlov (1997), who states that this species is nocturnal, Zhao et al. (1981) report that it is crepuscular, being active from early March into late November.^[2]

Feeding

They apparently feed on small mammals. A captured, immature specimen was found to have eaten a common gray shrew (Crocidura attenuata). In captivity, these snakes are reported to be reluctant feeders, but when they did they took newborn mice, and then only at night. On several occasions when feeding was observed, the prey was not released after being struck.^[2]

Venom

Research conducted by Dr. Bryan Grieg Fry indicates that the venom profile of the Fea's viper is remarkably similar to that of the Wagler's viper (Tropidolaemus wagleri).^[6] Another study found that enzyme activities in Azemiops feae venom gland extract are similar to those of viperine venoms, except that Azemiops venom has no blood clotting, haemorrhagic or myolytic activities. ^[7]

References

Further reading