Elapidae

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Elapidae
Egyptian cobra, Naja haje
Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Reptilia Order: Squamata Suborder: Serpentes Family: Elapidae Boie, 1827

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 that include 231 species are recognized.^[1]

Contents 1 Description 2 Venom 3 Genera 4 Taxonomy 5 References

[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. There are exceptions to all these generalizations: e.g. 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 and correlated morphological specialisations, e.g. for feeding on other snakes, elongate burrowing lizards, squamate eggs, mammals, birds, frogs, fish, etc.

Sea snakes, which are also elapids, 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 (Laticauda sp. ), are the least well-adapted to an aquatic life. They spend much of their time on land where they also lay their eggs (oviparous). They having wide ventral scales, the tail is not as well-developed for swimming, and their nostrils are separated by internasal scales. See also Sea snake.

All elapids have a pair of proteroglyphous fangs that are used to inject venom from glands located towards the rear of the upper jaws. The fangs are the first two teeth on each maxillary bone, which are enlarged and hollow, and usually only one is in place on each side at any time. The maxilla is intermediate in length and mobility between typical colubrids (long, less mobile) and viperids (very short, highly mobile). When the mouth is closed, the fangs fit into grooved slots in the buccal floor; in the longest-fanged elapids (e.g. Acanthophis, Oxyuranus) it is common for the fangs to pierce right through the intermandibular skin, which does not seem to endanger the snake. The fangs are usually below the front edge of the eye and are angled backwards; due to this construction, most 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. Some elapids (Acanthophis, Oxyuranus, and especially Dendroaspis) have long fangs on quite mobile maxillae (the prefrontal and ectopterygoid contacts are nearly as close together as in viperids), and can therefore make very fast stabbing strikes like viperids. A few species are capable of spraying their venom from forward facing holes at the tips of their fangs as a means of defense. 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[2]
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 (North Territory, Queensland, West 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	0		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	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).
Elapognathus	Boulenger, 1896	2	0	Southwestern grass snakes	Western Australia.
Elapsoidea	Bocage, 1866	10	7	African or Venomous Garter snakes (unrelated to North American non-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	The coasts of Timor (Indonesian sea), New Caledonia, Australia (North Territory, Queensland, West 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	North-western 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.[3]
Kerilia	Gray, 1849	1	0	Jerdon's sea snake	Southeast Asian waters.[3]
Kolpophis	M.A. Smith, 1926	1	0	Bighead sea snake	Indian Ocean.[3]
Lapemis	Gray, 1835	1	1	Shaw's sea snake	Persian Gulf to Indian Ocean, South China Sea, Indo-Australian archipelago and the western Pacific.[3]
Laticauda	Laurenti, 1768	5	0	Sea kraits	Southeast Asian and Indoaustralian waters.
Leptomicrurus	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	Schmidt, 1928	1	2	Western coral snakes	USA (Arizona, SW New Mexico), Mexico (Sonora, Sinaloa).
Micrurus	Wagler, 1824	69	54	Coral snakes	southern North America, South America.
Naja	Laurenti, 1768	20	5	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 and Scanlon, 2000	1	0	Lake Cronin snake	Western Australia.
Pelamis	Daudin, 1803	1	0	Yellow-bellied sea snake	Indian and Pacific Oceans.
Praescutata	Wall, 1921	1	0		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	Slowinski et al., 2001	5	4		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	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 above 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. There is now good molecular evidence 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.^[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.

[edit] References

v • d • e Snake families Chordata • Reptilia • Squamata Alethinophidia Acrochordidae • Aniliidae • Anomochilidae • Atractaspididae • Boidae • Bolyeriidae • Colubridae • Cylindrophiidae • Elapidae • Loxocemidae • Pythonidae • Tropidophiidae • Uropeltidae • Viperidae • Xenopeltidae Scolecophidia Anomalepididae • Leptotyphlopidae • Typhlopidae