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Elapidae

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Elapidae
Cobras are part of the Elapidae family
Cobras are part of the Elapidae family
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Elapidae
F. Boie, 1827
Subfamily: Elapinae
Hydrophiinae
Laticaudinae

Elapidae (Greek ἔλλοψ éllops, "sea-fish")[1] is a major family of venomous snakes found in tropical and subtropical regions around the world, terrestrially in Asia, Australia, Africa, North America and South America and aquatically in the Pacific and Indian Oceans. Elapid snakes exist in a wide range of sizes, from 18 cm species of Drysdalia to the 5.6 m (18 ft) Ophiophagus hannah (King cobra), and are characterized by hollow, fixed fangs through which they inject venom. Currently, 61 genera that include 325 species are recognized.[2]

Taxonomy

In the past, many subfamilies were recognized, or have been suggested for the Elapidae, including the Elapinae, Hydrophiinae (sea snakes), Micrurinae (coral snakes), Acanthophiinae (Australian elapids) and the Laticaudinae (sea kraits). Currently, none are universally recognized. There is now good molecular evidence via karyotyping and protein electrophoretic analysis, immunological distance, DNA sequence analysis etc. for reciprocal monophyly of two groups: the African, Asian and New World Elapinae, and Australasian and marine Hydrophiinae. Thus, the Australian terrestrial elapids are 'hydrophiines', though not sea snakes, while it is believed that Laticauda and the 'true sea snakes' evolved separately from among the Australasian land-snakes. Asian cobras, coral snakes, and American coral snakes also appear to be monophyletic, while African cobras do not.[3][4]

The type genus for the Elapidae was originally Elaps, but that group was moved to another family. In contrast to what usually happens in botany, the Elapidae family was not renamed. In the meantime, Elaps was renamed Homoroselaps and moved back to the Elapidae. However, Nagy et al. 2005 regard it as a sister taxon to Atractaspis which should therefore have been assigned to the Atractaspididae.

Description

In an examination of morphological characters, concluded that elapids fall into two groups: the palatine draggers and palatine erectors. "Palatine draggers" include Australasian terrestrial elapids (except Parapistocalamus) and hydrophiine sea snakes. In these species, the palatine acts as an anterior extension of the pterygoid, remaining horizontal even when the maxilla is erected. The "palatine erectors" include terrestrial African, Asian, and American elapids, the marine Laticauda, and Parapistocalamus. In these species, the palatine is erected along with the maxilla during protraction of the palate (McDowell, 1970). McDowell’s hypothesis was used in the snake classification of Smith et al. (1977), who divided Elapidae sensu lato into Elapidae sensu stricto and Hydrophiidae for the palatine erectors and draggers, respectively.[5]

All elapids have a pair of proteroglyphous fangs that are used to inject venom from glands located towards the rear of the upper jaws. In outward appearance terrestrial elapids look similar to the family Colubridae: almost all have long and slender bodies with smooth scales, a head that is covered with large shields and not always distinct from the neck, and eyes with round pupils. In addition, their behavior is usually quite active and most are oviparous. There are exceptions to all these generalizations, for example, the death adders (Acanthophis) include short and fat, rough-scaled, very broad-headed, cat-eyed, live-bearing, sluggish ambush predators with partly fragmented head shields.

Some elapids are strongly arboreal (African Pseudohaje and Dendroaspis, Australian Hoplocephalus), while many others are more or less specialised burrowers (e.g. Ogmodon, Parapistocalamus, Simoselaps, Toxicocalamus, Vermicella) in either humid or arid environments. Some species have very generalised diets, but many taxa have narrow prey preferences (stenophagy) and correlated morphological specialisations, e.g. for feeding on other snakes, elongate burrowing lizards, squamate eggs, mammals, birds, frogs, fish and others.

Sea snakes (Hydrophiinae, sometimes considered to be a separate family) have adapted to a marine way of life in different ways and to various degrees. All have evolved paddle-like tails for swimming and the ability to excrete salt. Most also have laterally compressed bodies, ventral scales are much reduced in size, their nostrils are located dorsally (no internasal scales) and give birth to live young (ovoviviparous). In general, they have the ability to respire through their skin; experiments with the yellow-bellied sea snake, Pelamis platurus, have shown that this species can satisfy about 20% of its oxygen requirements in this manner, allowing for prolonged dives. The sea kraits (Laticaudinae), are the sea snakes least adapted to an aquatic life. They spend much of their time on land, where they lay their eggs. They have wide ventral scales, the tail is not as well-developed for swimming, and their nostrils are separated by internasal scales.

Geographic distribution

On land, these snakes are found worldwide in tropical and subtropical regions, except in Europe. They occur in Africa, Asia, Oceania (Australia), the Middle East, North America and South America. Sea snakes occur mainly in the Indian Ocean and the southwest Pacific Ocean. However, the range of one species, Pelamis platura, extends across the Pacific to the coasts of Central and South America.

Venom

All elapids are venomous snakes which are potentially deadly. Their venom is mainly neurotoxic, although many of them also possess several other toxins, including cardiotoxin and cytotoxin. Some large-sized elapids, such as the Asiatic king cobra, African black mamba, and Australasian coastal taipan, can inject a high quantity of venom during envenomation. Elapids use their venom both to immobilize their prey and in self defense. The most venomous snake in the world is Belcher's sea snake, but on land the Inland taipan is considered to be the most venomous with a subcutaneous LD50 of 0.025 mg/kg.[6]

Genera

Genus[2] Taxon author[2] Species[2] Sub-species*[2] Common name Geographic range[7]
Acalyptophis Boulenger, 1869 1 0 spiny-headed seasnake Gulf of Thailand, South China Sea, the Strait of Taiwan, and the coasts of Guangdong, Indonesia, Philippines, New Guinea, New Caledonia, Australia (Northern Territory, Queensland, Western Australia)
Acanthophis Daudin, 1803 7 0 death adders Australia, New Guinea, Indonesia (Seram and Tanimbar)
Aipysurus Lacépède, 1804 7 1 olive sea snakes Timor Sea, South China Sea, Gulf of Thailand, and coasts of Australia (Northern Territory, Queensland, Western Australia), New Caledonia, Loyalty Islands, southern New Guinea, Indonesia, western Malaysia and Vietnam
Aspidelaps Fitzinger, 1843 2 4 shieldnose cobras South Africa (Cape Province, Transvaal), Namibia, southern Angola, Botswana, Zimbabwe, Mozambique
Aspidomorphus Fitzinger, 1843 3 3 collared adders New Guinea.
Astrotia Fischer, 1855 1 0 Stokes' sea snake Coastal areas from west India and Sri Lanka through Gulf of Thailand to China Sea, west Malaysia, Indonesia east to New Guinea, north and east coasts of Australia, Philippines
Austrelaps Worrell, 1963 3 0 copperheads Australia (South Australia, New South Wales, Victoria, Tasmania)
Boulengerina Dollo, 1886 2 1 water cobras Cameroon, Gabon, Democratic Republic of the Congo, Congo, Central African Republic, Tanzania, Equatorial Guinea, Rwanda, Burundi, Zambia
Bungarus Daudin, 1803 12 4 kraits India (incl. Andaman Island), Myanmar, Nepal, Vietnam, Afghanistan, Pakistan, Sri Lanka, Bangladesh, Cambodia, Indonesia (Java, Sumatra, Bali, Sulawesi), Peninsular Malaysia, Singapore, Taiwan, Thailand
Cacophis Günther, 1863 4 0 rainforest crowned snakes Australia (New South Wales, Queensland)
Calliophis Gray, 1834 8 11 Oriental coral snakes India, Bangladesh, Sri Lanka, Nepal, Indonesia, Cambodia, Malaysia, Singapore, Thailand, Burma, Brunei, Philippines, Vietnam, Laos, southern China, Japan (Ryukyu Islands), Taiwan
Demansia Gray, 1842 9 2 whipsnakes New Guinea, continental Australia
Dendroaspis Schlegel, 1848 4 1 mambas Kenya, Tanzania, Mozambique, Malawi, Zimbabwe, South Africa, Ghana, Togo, Benin, Nigeria, Cameroon, Guinea, Gabon, Principe (Gulf of Guinea), Central African Republic, Democratic Republic of the Congo, Congo, Uganda, Rwanda, Burundi, Equatorial Guinea, Angola, Sudan, Botswana, Burkina Faso, Eritrea, Senegal, Mali, Ethiopia, Ivory Coast, Namibia, Somalia, Swaziland, Zambia, Gambia, Guinea Bissau, Liberia, Ivory Coast, Sierra Leone
Denisonia Krefft, 1869 2 0 ornamental snakes Central Queensland and central northern New South Wales, Australia
Drysdalia Worrell, 1961 3 0 southeastern grass snakes Southern Australia (Western Australia, South Australia, Victoria, Tasmania, New South Wales)
Echiopsis Fitzinger, 1843 1 0 bardick Southern Australia (Western Australia, South Australia, Victoria, New South Wales)
Edichnopsis Young, 2009 2 0 Sebastian cobra (separate species) India, Sri Lanka, Nepal, Bhutan, South east China (including Tibet and Hong Kong), Northern Burma, Laos and Vietnam. Also found in Southern Cambodia
Elapognathus Boulenger, 1896 2 0 southwestern grass snakes Western Australia
Elapsoidea Bocage, 1866 10 7 African or venomous garter snakes (not related to North American garter snakes, which are nonvenomous) Senegal, South Africa, Mozambique, Namibia, Botswana, Zimbabwe, Swaziland, Gambia, Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Ghana, Ivory Coast, Malawi, Mali, Mauritania, Niger, Nigeria, Uganda, Senegal, Sudan, Tanzania, Togo, Democratic Republic of the Congo, Congo, Zambia, Kenya, north Burundi, Rwanda, Ethiopia, Uganda, Somalia
Emydocephalus Krefft, 1869 2 0 turtlehead sea snakes The coasts of Timor (Indonesian sea), New Caledonia, Australia (Northern Territory, Queensland, Western Australia), and in the Southeast Asian Sea along the coasts of China, Taiwan, Japan, and the Ryukyu Island
Enhydrina Gray, 1849 2 0 beaked sea snakes In the Persian Gulf (Oman, United Arab Emirates, etc.), south to the Seychelles and Madagascar,

SE Asian Sea (Pakistan, India, Bangladesh, Myanmar, Thailand, Vietnam), Australia (North Territory, Queensland), New Guinea and Papua New Guinea

Ephalophis M.A. Smith, 1931 1 0 Grey's mudsnake Northwestern Australia
Furina Duméril, 1853 3 0 pale-naped snakes Mainland Australia
Glyphodon Günther, 1858 2 0 brown-headed snakes Australia (Queensland), New Guinea
Hemachatus Fleming, 1822 1 0 spitting cobra South Africa, Zimbabwe, Lesotho, Swaziland
Hemiaspis Fitzinger, 1861 2 0 swamp snakes Eastern Australia (New South Wales, Queensland)
Hemibungarus Peters, 1862 1 2 Asian coral snakes Taiwan, Japan (Ryukyu Islands)
Homoroselaps Jan, 1858 2 0 harlequin snakes South Africa
Hoplocephalus Wagler, 1830 3 0 broad-headed snakes Eastern Australia (New South Wales, Queensland)
Hydrelaps Boulenger, 1896 1 0 Port Darwin mudsnake Northern Australia, southern New Guinea
Hydrophis Latreille In Sonnini & Latreille, 1801 34 3 sea snakes Indoaustralian and Southeast Asian waters.[8]
Kerilia Gray, 1849 1 0 Jerdon's sea snake Southeast Asian waters[8]
Kolpophis M.A. Smith, 1926 1 0 bighead sea snake Indian Ocean[8]
Lapemis Gray, 1835 1 1 Shaw's sea snake Persian Gulf to Indian Ocean, South China Sea, Indo-Australian archipelago and the western Pacific[8]
Laticauda Laurenti, 1768 5 0 sea kraits Southeast Asian and Indoaustralian waters
Leptomicrurus K.P. Schmidt, 1937 4 2 blackback coral snake Northern South America
Loveridgelaps McDowell, 1970 1 0 Solomons small-eyed snake Solomon Islands
Micropechis Boulenger, 1896 1 0 New Guinea small-eyed snake New Guinea
Micruroides K.P. Schmidt, 1928 1 2 Western coral snakes USA (Arizona, southwestern New Mexico), Mexico (Sonora, Sinaloa)
Micrurus Wagler, 1824 69 54 coral snakes Southern North America, South America
Naja Laurenti, 1768 23 3 cobras Africa, Asia
Notechis Boulenger, 1896 2 0 tiger snakes Southern Australia, including many offshore islands
Ogmodon Peters, 1864 1 0 bola Fiji
Ophiophagus Günther, 1864 1 0 king cobra Bangladesh, Myanmar, Cambodia, China, India, Andaman Islands, Indonesia, Laos, Thailand, Vietnam, west Malaysia, Philippines
Oxyuranus Kinghorn, 1923 2 2 taipans Australia, New Guinea
Parahydrophis Burger & Natsuno, 1974 1 0 Northern mangrove sea snake Northern Australia, southern New Guinea
Paranaja Loveridge, 1944 1 2 many-banded snakes West/central Democratic Republic of the Congo, Congo, Cameroon
Parapistocalamus Roux, 1934 1 0 Hediger's snake Bougainville Island, Solomons
Paroplocephalus Keogh, Scott & Scanlon, 2000 1 0 Lake Cronin snake Western Australia
Pelamis Daudin, 1803 1 0 yellow-bellied sea snake Indian and Pacific Oceans
Praescutata viperina Wall, 1921 1 0 viperine sea snake Persian Gulf, Indian Ocean, South Chinese Sea northeast to coastal region of Fujian and Strait of Taiwan
Pseudechis Wagler, 1830 7 0 black snakes (and king brown) Australia
Pseudohaje Günther, 1858 2 0 forest cobras Angola, Burundi, Cameroon, Central African Republic, Democratic Republic of the Congo, Congo, Gabon, Ghana, Kenya, Nigeria, Rwanda, Uganda, Sierra Leone, Liberia, Ivory Coast, Togo, Nigeria
Pseudonaja Günther, 1858 8 2 venomous brown snakes (and dugites) Australia
Rhinoplocephalus Müller, 1885 6 0 Australian small-eyed snakes Southern and eastern Australia, southern New Guinea
Salomonelaps McDowell, 1970 1 0 Solomons coral snake Solomon Islands
Simoselaps Jan, 1859 13 3 Australian coral snakes Mainland Australia
Sinomicrurus (Calliophis) macclellandi Slowinski et al., 2001 5 4 MacClelland’s (Asian) coral snake India, Myanmar, Vietnam, China, Taiwan, Japan
Suta Worrell, 1961 10 2 hooded snakes (and curl snake) Australia
Thalassophis P. Schmidt, 1852 1 0 anomalous sea snake South Chinese Sea (Malaysia, Gulf of Thailand), Indian Ocean (Sumatra, Java, Borneo)
Toxicocalamus Boulenger, 1896 9 0 New Guinea forest snakes New Guinea (and nearby islands)
Tropidechis Günther, 1863 2 0 rough-scaled snake Eastern Australia
Vermicella Gray In Günther, 1858 5 0 bandy-bandies Australia
Walterinnesia Lataste, 1887 2[9] 0 black desert cobra Egypt, Israel, Lebanon, Syria, Jordan, Iraq, Iran, Kuwait, Saudi Arabia, Turkey [10]

* Not including the nominate subspecies

Cited references

  1. Definition of 'elapid'.. dictionary.com. Retrieved on 7 May 2012.
  2. 2.0 2.1 2.2 2.3 2.4 Elapidae (TSN 174348) at Integrated Taxonomic Information System. Accessed 7 May 2012.
  3. Joseph Bruno Slowinski and Keogh J. S. (April 2000). "Phylogenetic Relationships of Elapid Snakes Based on Cytochrome b mtDNA Sequences". Molecular Phylogenetics and Evolution 15 (1): 157–64. PMID 10764543.
  4. Williams D, Wuster W, Fry B. G (July 2006). "The good, the bad and the ugly: Australian snake taxonomist and a history of the taxonomy of Australia's venomous snakes". Toxicon 48 (1): 919–30. PMID 16999982.
  5. Slowinski, Joseph. Knight, Alec. Rooney, Alejandro. (December 1996). "Inferring Species Trees from Gene Trees: A Phylogenetic Analysis of the Elapidae (Serpentes) Based on the Amino Acid Sequences of Venom Proteins." Molecular Phylogenetics and Evolution Vol. 8. No. 3. pp. 349–362. FY970434
  6. LD50 Menu at Venom Doc. Australian Venom Research Unit. University of Queensland. Accessed 7 May 2012.
  7. Elapidae at The Reptile Database. Accessed 7 May 2012.
  8. 8.0 8.1 8.2 8.3 The Hydrophiidae at Cyberlizard's home pages. Accessed 7 May 2012.
  9. Nilson, G. & N. Rastegar-Pouyani (2007) Walterinnesia aegyptia Lataste, 1887 (Ophidia: Elapidae) and the status of Naja morgani Mocquard 1905. Russian Journal of Herpetology, 14: 7-14.
  10. Ugurtas, I. H., T. J. Papenfuss and N. L. Orlov. 2001. New record of Walterinnesia aegyptia Lataste, 1887 (Ophidia: Elapidae: Bungarinae) in Turkey. Russian Journal of Herpetology. 8(3):239-245.