Vipera darevskii

Vipera darevskii is a small venomous viper species endemic to northwestern Armenia, northeastern Turkey, and possibly also adjacent southern Georgia.[2] No subspecies are currently recognized.[3]

Vipera darevskii
Adult male Darevsky's viper from Armenia
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Genus: Vipera
Species:
V. darevskii
Binomial name
Vipera darevskii
Vedmederja, Orlov & Tuniyev, 1986[1]
Common names: Darevsky's viper.[2]

Etymology

The specific name, darevskii, is in honor of Russian herpetologist Ilya Sergeyevich Darevsky.[4]

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 there is sexual dimorphism in size, color, and pattern appearance. The reported maximum total length (body + tail) for females is 42.1 cm (16.6 in). The total length of the largest male was 25.8 cm (10.2 in).[2] 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

This ovoviviparous snake 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 babies 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

This mountainous snake is only known from the southwestern Dzavakhety Mountains in Shirak Marz of Armenia, on Madatapa, Javakheti Ridge, Erusheti Mountains and Akhaltsihe Highland Georgia and the east of the Artvin Province and Ardahan Province of Turkey.

The type locality given is "Mount Leghli" (Achkasar), Mokrye mountains (Wet mountains), Gukasyanskii region(former Ghukasyan district), Armenia."[1] This species are also present in adjacent areas in Georgia and Turkey.

Habitat and ecology

The mountain ridges supporting Darevsky's viper have unique climate conditions. They compose the coldest and the most humid region of the Armenian Highland. The average annual precipitation here is about 1,000 mm (39 in). Even during the hottest and driest months of July and August, hot days lead to intensive evaporation of humidity and cloud formation. Almost every evening, aggregating clouds release some, often heavy, showers and remoisturize the environment. At night temperatures regularly drop down to just 4-6 °C (39-43 °F), and morning sunrays regularly have to cut through the dense fog, before they reach the east-facing slopes and provide heat necessary for functioning of this viper. In some north-facing patches, close to the watersheds and summits of mountain ridges, some residual snow and ice never melts. Such patches as a rule are unsuitable for snakes. Suitable patches of rocky deposits are mainly situated on the steep and warmest south-facing and southeast-facing slopes of deep mountain valleys within an elevation range of 2300–3000 m (7,550-9,840 ft) above sea level.

High mountainous moraines, as well as outcrops of bedrock surrounded by alpine grasslands, are being utilized as the main habitat by this snake. Deposits of rocks provide snakes with deep hibernation dens, but also serve as daily shelters and protection from overheating and/or overcooling as well as from predators. Also rocky deposits support important food resources: rock lizards (mainly Darevskia valentini) and small rodents (Microtus ssp.). Darevsky's vipers are diurnal snakes, and during the day they often move inside the rocky deposits to maintain optimal body temperature, which is about 26–28 °C (79-82 °F). Very little is known about natural enemies of this viper. Remains of this snake were found in the feces of a beech marten (Martes foina nehringi).

Land use and protection

Slopes of ridges supporting Darevsky's viper are being regularly used by local residents as pasture for domestic cattle, and are being mowed. Currently the major part of the habitat of this snake in Armenia is included in the Lake Arpi National Park.

Conservation status

This species is classified as critically endangered (CR) according to the IUCN Red List of Threatened Species with the following criteria: B1ab(ii,iii)+2ab(ii,iii) (v3.1, 2001).[5] This indicates that its extent of occurrence is estimated to be less than 100 km2, its area of occupancy is estimated to be less than 10 km2, its population is severely fragmented and a continuing decline is observed, projected, or inferred, in the extent of its habitat.[6] Year assessed: 2009.

References
  1. McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
  2. Mallow D, Ludwig D, Nilson G. 2003. True Vipers: Natural History and Toxinology of Old World Vipers. Malabar, Florida: Krieger Publishing Company. 359 pp. ISBN 0-89464-877-2.
  3. "Vipera darevskii ". Integrated Taxonomic Information System. Retrieved 17 August 2006.
  4. Beolens B, Watkins M, Grayson M. 2011. The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Vipera darevskii, p. 65).
  5. Vipera darevskii at the IUCN Red List. Accessed 13 May 2014.
  6. 2001 Categories & Criteria (version 3.1) at the IUCN Red List. Accessed 13 May 2014.

Further reading
  • Aghasyan, A.L. 1996. [The Fauna of Snakes of Armenia and Nakhichevan]. Ph.D. thesis. Yerevan. 34 pp. (In Russian).
  • Aghasyan, A.L., and Aghasyan, L.A. 2009. Conservation and further research of distribution of the critically endangered Darevsky's viper (Vipera darevskii) in Armenia. Project final report. Yerevan. 51 p.
  • Ananjeva, N.B.; Borkin, L.Ya.; Darevsky, I.S.; Orlov, N.L. 1998. [Encyclopedia of Russian Nature: Amphibians and Reptiles]. Moscow: ABF Publishing. 351 pp. (In Russian).
  • Ananjeva, N.B.; Orlov, N.L.; Khalikov, R.G.; Darevsky, I.S.; Rjabov, S.A.; Barabanov, A.V. 2004. [Atlas of Reptiles of Northern Eurasia]. Saint Petersburg, Russia: "Ivan Fedorov" Printing. 230 pp. (In Russian).
  • Darevsky, I.S. 1957. [The Fauna of Reptiles of Armenia and its Zoogeographical Analysis]. Ph.D. Thesis. Yerevan. 468 pp.(In Russian).
  • Darevsky, I.S. 1956. [A new species of the venomous snake, Vipera kaznakowi Nikolsky, for the fauna of Armenia]. Bulletin of the Academy of Sciences of Armenia, Yerevan 9 (12): 127–130. (In Russian).
  • Geniez, P., and Tynié, A. 2005. Discovery of a population of the critically engangered Vipera darevskii Vedmederja, Orlov & Tuniyev, 1986 in Turkey, with new elements on its identification (Reptilia: Squamata: Viperidae). Herpetozoa 18 (1/2): 25–33.
  • Orlov, N.L., and B.S. Tuniyev. 1986. [Present ranges, possible ways of their formation and phylogeny of the three species of vipers from the Eurosiberic group (V. kaznakowi complex) in the Caucasus]. Proceedings of the Zoological Institute, USSR Academy of Sciences, Leningrad 157: 104–135. (In Russian).
  • Avci, A.; Ilgas, C.; Baskaya, S.; Baran, I.; Kumlutas, Y. 2010. Contribution to the distribution of Pelias darevskii (Vedmederja, Orlov & Tunyev, 1986) (Reptilia: Squamata: Viperidae) in Northeastern Anatolia. Russian Journal of Herpetology 17 (1): 1–7.
  • Tadevosyan, T.L. 2002. [Poisonous Snakes as an Ecological Risk Factor and the Ways of its Neutralisation. Proceedings of the Third Republican Youth Scientific Conference "21st century: Ecological Science in Armenia"]. Yerevan. pp. 20–36.(In Armenian).
  • Tadevosyan, T.L. 2003. [Modern Anthropogenic Impact on the Population of Darevsky's viper, Pelias (Vipera sensu lato) darevskii Vedmederja, Orlov & Tunyev, 1986, in the Limits of the Southern Part of Javakhety Ridge (Armenia)]. [Materials of the Regional Scientific Conference to Consecrate 60 years of the Institute of Zoology, National Academy of Sciences, Republic of Armenia]. Yerevan. pp. 143–144. (In Russian).
  • Tadevosyan, T.L. 2004. [Mapping of the Presumed Range of Darevsky's viper]. [8th Pushinskaja School Conference of Young scientists]. (In Russian).
  • Vedmederja, V.I. 1984. [Range, variability and peculiarities of ecology of the Caucasus viper]. pp. 8–9. In [Species and their Productivity in the Habitat. Part V. Questions of Herpetology]. Sverdlovsk. (In Russian).
  • Tuniyev, S.B., Iremashvili, G.N., De Las Heras, B., Tuniyev, B.S.2014. About Type Locality and Finds of Darevsky's Viper [Pelias darevskii (Vedmederja, Orlov et Tuniyev, 1986) Reptilia: Viperinae] in Georgia. Russian Journal of herpetology, Vol. 21, No 4., 2014, pp. 281–290.
  • Vedmederja, V.I.; N.L. Orlov; B.S. Tuniyev. 1986. [On the taxonomy of three viper species of the Vipera kaznakowi complex]. Proceedings of the Zoological Institute, Leningrad 157: 55–61. (In Russian).
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