Elapidae
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 Egyptian cobra, Naja haje
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The Elapidae, or elapids, are a family of venomous snakes found in tropical and subtropical regions around the world, including the Indian Ocean and the Pacific. They are characterized by possessing a set of hollow, fixed fangs through which they inject venom, and come in a wide range of sizes, from only 18 cm (Drysdalia) up to 6 m in length (Ophiophagus). Currently, 61 genera are recognized.[1]
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[edit] Description
Outwardly, terrestrial elapids look similar to the 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.
Sea snakes, which are also elapids, have adapted to a marine way of life in different ways and to various degrees. Characteristics can include laterally compressed bodies, rudder-like tails for swimming, the ability to excrete salt and give birth to live young (ovoviviparous). Some genera, including Hydrophis, have ventral scales that are much reduced in size. Others, like the olive sea snakes (Aipysurus sp.) can absorb oxygen from the surrounding water directly through their skin and may obtain 10-22% in this manner. The sea kraits (Laticauda sp.), seem to be the least well-adapted to an aquatic life, having wide ventral scales, a poorly developed tail fin and needing to return to land in order to mate and lay eggs (oviparous).
All elapids have a pair of proteroglyphous (hollow) fangs that are used to inject venom from glands located towards the rear of the upper jaws. Each of the two fangs is located at the front of the mouth on a largely immovable and short maxillary bone. When the mouth is closed, the fangs fit into grooved slots in the buccal floor. Due to this construction, elapids must actually bite in order to envenomate. This action is therefore not as quick as with the viperids, that can envenomate with only a quick, stabbing motion. Elapids use their venom both to immobilize their prey and in self-defense.
[edit] Venom
All elapids are venomous and many are potentially deadly. The venoms are mostly neurotoxic and are considered more dangerous than the mainly proteolytic viper venoms. Members include the black mamba (Dendroaspis polylepis), a species many regard as the world's most dangerous snake, the fierce snake (Oxyuranus microlepidotus), which is the most venomous land snake, and Hydrophis belcheri, a sea snake and the most toxic venom of all snakes.
[edit] Genera
| Genus[1] | Authority[1] | Species[1] | Subsp.*[1] | Common name | Geographic range |
|---|---|---|---|---|---|
| Acalyptophis | Boulenger, 1869 | 1 | 0 | Spiny-headed seasnake | Gulf of Thailand, South China sea, coast of Guangdong and Strait of Taiwan, Indonesia, Philippines, New Guinea, New Caledonia, Australia (Northern Territory, Queensland, Western Australia) |
| Acanthophis | Daudin, 1803 | 7 | 0 | Death adders | Australia, New Guinea, Indonesia (Seram, Tanimbar) |
| Aipysurus | Lacépède, 1804 | 7 | 1 | Timor Sea, South China Sea, Gulf of Thailand, coast of Australia (North Territory, Queensland, West Australia), New Caledonia, Loyalty Islands, southern New Guinea, Indonesia, western Malaysia, Vietnam | |
| Aspidelaps | Fitzinger, 1843 | 2 | 4 | Shieldnose cobras | South Africa (Cape Province, Transvaal), Namibia, southern Angola, Botswana, Zimbabwe,Mozambique |
| Aspidomorphus | Fitzinger, 1843 | 3 | 0 | Collared adders | New Guinea |
| Astrotia | Fischer, 1855 | 1 | 0 | Stoke's 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 | Australian 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 | Indian kraits | India (incl. Andaman Island), Myanmar, Nepal, Vietnam, Afghanistan, Pakistan, Sri Lanka, Bangladesh, Cambodia, Indonesia (Java, Sumatra, Bali, Sulawesi), Peninsular Malaysia, Singapore, Thailand |
| Cacophis | Günther, 1863 | 4 | 0 | Dwarf 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 (Ryūkyū Islands), Taiwan |
| Demansia | Gray, 1842 | 9 | 2 | Venomous whip snakes | 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 | Australian crowned snakes | Australia |
| Echiopsis | Fitzinger, 1843 | 2 | 0 | Bardick snakes | Australia |
| Elapognathus | Boulenger, 1896 | 2 | 0 | Little brown snakes | Australia |
| Elapsoidea | Bocage, 1866 | 10 | 7 | Venomous garter snakes | 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 | |
| Enhydrina | Gray, 1849 | 2 | 0 | Beaked sea snakes | |
| Ephalophis | M.A. Smith, 1931 | 1 | 0 | Grey's sea snake | |
| Furina | Duméril, 1853 | 5 | 0 | Naped snakes | |
| Hemachatus | Fleming, 1822 | 1 | 0 | Spitting cobra | South Africa, Zimbabwe, Lesotho, Swaziland |
| Hemiaspis | Fitzinger, 1861 | 2 | 0 | Swamp snakes | |
| Hemibungarus | Peters, 1862 | 1 | 2 | Asian coral snakes | Taiwan, Japan (Ryūkyū Islands) |
| Homoroselaps | Jan, 1858 | 2 | 0 | Harlequin snakes | |
| Hoplocephalus | Wagler, 1830 | 3 | 0 | Pale-headed snakes | Eastern Australia |
| Hydrelaps | Boulenger, 1896 | 1 | 0 | Port Darwin seasnake | |
| Hydrophis | Latreille In Sonnini & Latreille, 1801 | 34 | 3 | Asian sea snakes | |
| Kerilia | Gray, 1849 | 1 | 0 | Jerdon's sea snake | |
| Kolpophis | M.A. Smith, 1926 | 1 | 0 | Bighead sea snake | |
| Lapemis | Gray, 1835 | 1 | 1 | Shaw's sea snake | |
| Laticauda | Laurenti, 1768 | 5 | 0 | Sea kraits | |
| Leptomicrurus | Schmidt, 1937 | 4 | 2 | Blackback Coral Snake | |
| Loveridgelaps | McDowell, 1970 | 1 | 0 | Solomon's small-eyed snake | |
| Micropechis | Boulenger, 1896 | 1 | 0 | New Guinea small-eyed snake | |
| Micruroides | Schmidt, 1928 | 1 | 2 | Western coral snakes | USA (Arizona, SW New Mexico), Mexico (Sonora, Sinaloa) |
| Micrurus | Wagler, 1824 | 69 | 54 | Coral snakes | |
| Naja | Laurenti, 1768 | 20 | 5 | Cobras | |
| Notechis | Boulenger, 1896 | 2 | 0 | Tiger snakes | Southern Australia, including many offshore islands |
| Ogmodon | Peters, 1864 | 1 | 0 | Fiji cobra | |
| 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 | 1 | Taipans | Australia, New Guinea |
| Parahydrophis | Burger & Natsuno, 1974 | 1 | 0 | Northern mangrove sea snake | |
| 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 | |
| Pelamis | Daudin, 1803 | 1 | 0 | Yellow-bellied sea snake | |
| Praescutata | Wall, 1921 | 1 | 0 | ||
| 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 | ||
| Salomonelaps | McDowell, 1970 | 1 | 0 | Solomons coral snake | |
| Simoselaps | Jan, 1859 | 13 | 3 | Australian coral snakes | |
| Sinomicrurus | Slowinski et al., 2001 | 5 | 4 | ||
| Suta | Worrell, 1961 | 10 | 2 | Curl Snake | Australia |
| Thalassophis | P. Schmidt, 1852 | 1 | 0 | Anomalous sea snake | |
| Toxicocalamus | Boulenger, 1896 | 9 | 0 | Forest snakes | |
| Tropidechis | Günther, 1863 | 2 | 0 | Rough-scaled snake | Eastern Australia |
| Vermicella | Gray In Günther, 1858 | 5 | 0 | Bandy-bandies | |
| Walterinnesia | Lataste, 1887 | 1 | 0 | Black desert cobra | Egypt, Israel, Lebanon, Syria, Jordan, Iraq, Iran, Kuwait, Saudi Arabia |
*) Not including the nominate subspecies (typical form).
[edit] Taxonomy
The table below lists all of the elapid genera and no subfamilies. 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. It seems certain that the elapids will be broken up eventually, but there are still a number of unresolved issues as to how this should be done. One involves the former Hydrophiidae, a group for which Rasmussen (2002) provided evidence suggesting that its members are phylogenetically more related to other elapids than they are to each other.
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.
[edit] Cited references
- ^ a b c d e Elapidae (TSN 174348). Integrated Taxonomic Information System. Accessed on 27 November 2006.
[edit] External links
- EMBL Reptile Database - Family Elapidae
- Integrated Taxonomic Information System - Elapidae
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