Darevsky's Viper

Vipera darevskii, known as Darevsky's viper, is a small species of viper, a venomous snake in the subfamily Viperinae of the family Viperidae. The species is native to northwestern Armenia, northeastern Turkey, and possibly also adjacent southern Georgia. There are no subspecies that are recognized as being valid.

Etymology

The specific name, darevskii, is in honor of Russian herpetologist Ilya Sergeyevich Darevsky.

Venom

Darevsky's viper is a relatively small venomous snake. Its bite is painful and will cause local swelling, but appears not to be life-threatening to adult humans.

Description

In this species, V. darevskii, there is sexual dimorphism in size, color, and pattern appearance. The reported maximum total length (including tail) for females is 42.1 cm (16.6 in). The total length of the largest male was 25.8 cm (10.2 in). The dorsal surface of V. darevskii has a light brown to grey background color, with a dark brown to black (often broken) zigzag pattern along the back, and a single row of small dark blotches on each side of the body. The belly has a pattern of numerous grey or black dots. In females the belly is greyer, while in males it is almost black with some white fragments on the edges of the ventral scales. The chin shields and labial scales are white, with few dark fang-shaped markings on the labials, which makes this species different from the related Vipera eriwanensis, which has a somewhat pink tint on the labials. In general adult males are noticeably brighter and have more color contrast compared to females. Females have a browner background color and a less pronounced brown pattern; while adult males have a relatively light background color with a yellow tint, and a dark, often black, pattern.

The dorsal scales are keeled. The dorsal surface of the head anterior to the frontal (the area sometimes called the pileus) carries a complex of enlarged shields.

Natural history

Little is known about the ontogenetic development and the life span of Darevsky's viper.

Diet

Like all other snakes, Darevsky's viper is a predator. It forages on lizards, small rodents, and orthopterans. Due to the potent venom, the digestion process is very fast. Digestion of fuzzy rats in vipers kept at 4–7 °C (39–45 °F) lasted only 3 days. A speculation exists that these snakes need a lot of food.

Reproduction

An ovoviviparous snake, V. darevskii mates in May, after the first spring shed. Females feed intensively throughout the warm season, and give birth to 4–8 babies in September to Early October. Newborn babies are just 15–18 cm (5.9–7.1 in) long (including tail), and weigh about 0.5 g (0.018 oz).

Neonates

During their first two weeks, newborn V. darevskii consume the residual nutrition from the yolk. They grow without eating and get ready for the first shed which takes place within 10–14 days. It is unknown, whether baby vipers forage before their first hibernation or not. Generally baby Daresky's vipers feed on newborn rock lizards (Darevskia valentini) and small orthopterans.

Geographic range