| Fea's viper | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Vertebrata |
| Class: | Reptilia |
| Order: | Squamata |
| Suborder: | Serpentes |
| Family: | Viperidae |
| Subfamily: | Azemiopinae Liem, Marx & Rabb, 1971 |
| Genus: | Azemiops Boulenger, 1888 |
| Species: | A. feae |
| Binomial name | |
| Azemiops feae Boulenger, 1888[1] |
|
Azemiopinae is a monotypic subfamily created for the monotypic genus, Azemiops, that contains the venomous viper species Azemiops feae, described here. No subspecies are recognized.[2] The first specimen was collected by Italian explorer Leonardo Fea, and was described as a new genus and new species by Boulenger in 1888.[3] Considered to be one of the most primitive vipers,[4] it is found in the mountains of South East Asia[5] in China, southeastern Tibet and Vietnam.[3] Its common name is Fea's viper.[3]
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This species does not grow 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.[3]
It is considered to be 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 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. Finally, unlike most vipers, Fea's viper is oviparous and hibernates during the winter months.[3]
The color pattern of Fea's viper is striking: dorsally its basic body color is a shiny, deep blue-gray to black, marked by a number of widely spaced thin (1-2 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.[3] 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). Ventral count is around 180, subcaudals around 40.
Internasals and prefrontals subequal in length. Frontal slightly broader than long, nearly 3 times as broad as the supraocular. Parietals as long as their distance from the end of the snout. Loreal small, pentagonal, as tall as long. Two (or three) preoculars. Two postoculars. Two large superposed anterior temporals, only the upper in contact with the postoculars. Six upper labials, first and second smallest, third entering the eye, fourth and fifth largest. Seven lower labials, first large and forming a suture with its fellow, second small. One pair of short chin shields.[6]
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]
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 crepuscular, prefers temperatures of 18-25 °C, and very moist environments for shelter.[3]
This species has a characteristic threat display. When disturbed, it flattens its body to make itself look wider, and its jaws flare outwards posteriorly, 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.[3]
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.[3]
Research conducted by Dr. Bryan Grieg Fry indicates that the venom profile of Fea's viper is remarkably similar to that of Wagler's viper (Tropidolaemus wagleri).[7] 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. [8]