Elapidae

Elapidae (/ɪˈlæpɪdiː/, commonly known as elapids /ˈɛləpɪdz/; Ancient Greek: ἔλλοψ éllops "sea-fish"[6]) is a family of venomous snakes characterized by their permanently erect fangs at the front of the mouth. Many members of this family are also recognized by their threat display of rearing upwards while spreading the neck-flap. Elapids are endemic to tropical and subtropical regions around the world, with terrestrial forms in Asia, Australia, Africa, and the Americas alongside marine forms in the Pacific and Indian Oceans. Members of the family have a wide range of sizes, from the 18 cm (7.1 in) white-lipped snake to the 5.85 m (19 ft 2 in) king cobra. Most species have neurotoxins in their venom which is channeled by those hollow fangs, while some may contain other toxic components in various proportions. The family includes 55 genera with some 360 species and over 170 subspecies.

Elapidae
King cobra (Ophiophagus hannah), the world's longest venomous snake
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Superfamily: Elapoidea
Family: Elapidae
F. Boie, 1827
Subfamilies and genera[lower-alpha 1]

Description

Appearance

Terrestrial elapids look similar to the Colubridae; almost all have long, slender bodies with smooth scales, a head 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. Exceptions to all these generalizations occur: 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.

Sea snakes (the 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, their ventral scales are much reduced in size, their nostrils are located dorsally (no internasal scales), and they give birth to live young (viviparity). The reduction in ventral scaling has greatly diminished their land mobility, but aids in swimming.

Members of this family have a wide range of sizes. Drysdalia species are small serpents typically 50 cm (20 in) and down to 18 cm (7.1 in) in length. Cobras, mambas, and taipans are mid- to large sized snakes which can reach 2 m (6 ft 7 in) or above. The king cobra is the world's longest venomous snake with a maximum length of 5.85 m (19.2 ft) and an average mass of 6 kg (13 lb).[7]

Behavior

Most elapids are terrestrial, while some are strongly arboreal (African Pseudohaje and Dendroaspis, Australian Hoplocephalus). Many species are more or less specialized burrowers (e.g. Ogmodon, Parapistocalamus, Simoselaps, Toxicocalamus, and Vermicella) in either humid or arid environments. Some species have very generalised diets (euryphagy), but many taxa have narrow prey preferences (stenophagy) and correlated morphological specializations, for example feeding almost exclusively on other serpents (especially the king cobra and kraits). Elapids may display a series of warning signs if provoked, either obviously or subtly. Cobras and mambas lift their inferior body parts, expand hoods, and hiss if threatened; kraits often curl up before hiding their heads down their bodies.

In general, sea snakes are able to respire through their skin. Experiments with the yellow-bellied sea snake, Hydrophis 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 spp.) are the sea snakes least adapted to aquatic life. Their bodies are less compressed laterally, and they have thicker bodies and ventral scaling. Because of this, they are capable of some land movement. They spend much of their time on land, where they lay their eggs and digest prey.

Dentition
The lateral view of a king cobra's skull showing fangs

All elapids have a pair of proteroglyphous fangs to inject venom from glands located towards the rear of the upper jaw. The fangs, which are enlarged and hollow, are the first two teeth on each maxillary bone. Usually only one fang is in place on each side at any time. The maxilla is intermediate in both 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 and usually below the front edge of the eye and are angled backwards; some elapids (Acanthophis, taipan, mamba, and king cobra) have long fangs on quite mobile maxillae and can make fast strikes. A few species are capable of spraying their venom from forward-facing holes in their fangs for defense, as exemplified by spitting cobras. Venom may cause intense pain, if not blindness, upon contact with eyes.[8]

Distribution

Terrestrial elapids are found worldwide in tropical and subtropical regions, mostly in the Southern Hemisphere. Most prefer humid tropical environments, and so are not found in the Sahara or Middle East, although some can be found in Mexican and Australian deserts. Sea snakes occur mainly in the Indian Ocean and the south-west Pacific. They occupy coastal waters and shallows, and are common in coral reefs. However, the range of Hydrophis platurus extends across the Pacific to the coasts of Central and South America.[9]

Venom

Venoms of species in the Elapidae are mainly neurotoxic for immobilizing prey and defense. The main group of toxins are PLA2 and Three finger toxins (3FTx). Other toxic components in some species comprise cardiotoxins and cytotoxins, which cause heart dysfunctions and cellular damage, respectively. All members are venomous to varying extents, and some are considered among the world's most venomous snakes based upon their murine LD50 values, such as the taipans.[10] Large species, mambas and cobras included, are dangerous for their capability of injecting high quantities of venom upon single envenomation and/or striking at a high position proximal to the victim's brain, which is vulnerable to neurotoxicity. Antivenom is promptly required to be administrated if bitten by any elapids. Venom of spitting cobras is more cytotoxic rather than neurotoxic. It damages local cells, especially those in eyes, which are deliberately targeted by the snakes. The venom may cause intense pain if not blindness upon contact with eyes. It is not lethal on skin if no wound provides any chance for the toxins to make contact with the blood.[8] Specific antivenoms are the only cure to treat elapidae bites. There are commercial monovalent and polyvalent antivenoms for Mambas, Cobras, Najas, and some other important elapids. Recently, experimental antivenoms based on recombinant toxins have a shown that is feasible to create antivenoms with a wide spectrum of coverage.[11]

Taxonomy

The table below lists out 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. Molecular evidence via techniques like karyotyping, protein electrophoretic analyses, immunological distance and DNA sequencing, suggests reciprocal monophyly of two groups: African, Asian, and New World Elapinae versus Australasian and marine Hydrophiinae. The Australian terrestrial elapids are technically 'hydrophiines', although they are not sea snakes. It is believed that the Laticauda and the 'true sea snakes' evolved separately from Australasian land snakes. Asian cobras, coral snakes, and American coral snakes also appear to be monophyletic, while African cobras do not.[12][13]

The type genus for the Elapidae was originally Elaps, but the group was moved to another family. In contrast to what is typical of botany, the family Elapidae 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 have been assigned to the Atractaspidinae.

Genus[14] Taxon
author[14]		 Species[14] Subspecies*[14] Common
name		 Geographic
range[9]
Acanthophis Daudin, 1803 7 0 death adders Australia, New Guinea, Indonesia (Seram Island 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
Antaioserpens Wells & Wellington, 1985 2 0 burrowing snakes Australia
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
Austrelaps Worrell, 1963 3 0 copperheads Australia (South Australia, New South Wales, Victoria, Tasmania)
Boulengerina Dollo, 1886 2 1 water cobras Cameroon, Gabon, the Democratic Republic of the Congo, Congo, the Central African Republic, Tanzania, Equatorial Guinea, Rwanda, Burundi, Zambia
Brachyurophis Günther, 1863 7 0 shovel-nosed snakes Australia
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 15 11 Oriental coral snakes India, Bangladesh, Sri Lanka, Nepal, Indonesia, Cambodia, Malaysia, Singapore, Thailand, Burma, Brunei, the Philippines, Vietnam, Laos, southern China, Japan (Ryukyu Islands), Taiwan
Cryptophis Worrell, 1961 5 0 Australia and Papua New Guinea
Demansia Gray, 1842 9 2 whipsnakes New Guinea, continental Australia
Dendroaspis Schlegel, 1848 4 1 mambas Sub-Saharan Africa
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 (not related to North American garter snakes, which are harmless to humans) Sub-Saharan Africa
Emydocephalus Krefft, 1869 3 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 Islands
Enhydrina Gray, 1849 2 0 beaked sea snakes In the Persian Gulf (Oman, United Arab Emirates, etc.), south to the Seychelles and Madagascar,

Southeast 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 A.M.C. Duméril, 1853 5 0 pale-naped snakes Mainland Australia, southern New Guinea, Aru Islands
Hemachatus Fleming, 1822 1 0 rinkhals/ring-necked spitting cobra South Africa, Zimbabwe, Lesotho, Swaziland
Hemiaspis Fitzinger, 1861 2 0 swamp snakes Eastern Australia (New South Wales, Queensland)
Hemibungarus W. Peters, 1862 3 0 Barred coral snakes Philippines (Luzon, Panay, Negros, Cebu, Polillo is.)
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.[15]
Incongruelaps 1 0 Riversleigh, Australia[16]
Laticauda Laurenti, 1768 5 0 sea kraits Southeast Asian and Indo-Australian waters
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 United States (Arizona, southwestern New Mexico), Mexico (Sonora, Sinaloa)
Micrurus Wagler, 1824 80 54 coral snakes Southern North America, South America
Naja Laurenti, 1768 36 3 cobras Africa, Asia
Neelaps (Duméril, Bibron & Duméril, 1854) 1 0 Australia
Notechis Boulenger, 1896 2 0 tiger snakes Southern Australia, including many offshore islands
Ogmodon W. Peters, 1864 1 0 bola Fiji
Ophiophagus Günther, 1864 1 0 King cobra Bangladesh, Myanmar, Cambodia, China, India, Andaman Islands, Indonesia, Laos, Thailand, Vietnam, western Malaysia, the Philippines
Oxyuranus Kinghorn, 1923 3 2 taipans Australia, New Guinea
Parahydrophis Burger & Natsuno, 1974 1 0 Northern mangrove sea snake Northern Australia, southern New Guinea
Parapistocalamus Roux, 1934 1 0 Hediger's snake Bougainville Island, Solomons
Paroplocephalus Keogh, Scott, and Scanlon, 2000 1 0 Lake Cronin snake Western Australia
Pseudechis Wagler, 1830 7 0 black snakes (and king brown) Australia
Pseudohaje Günther, 1858 2 0 tree 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 F. Müller, 1885 1 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, Boundy, & Lawson, 2001 8 8 Asia
Suta Worrell, 1961 11 0 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 11 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 6 0 bandy-bandies Australia
Walterinnesia Lataste, 1887 2[17] 0 black desert cobra Egypt, Israel, Lebanon, Syria, Jordan, Iraq, Iran, Kuwait, Saudi Arabia, Turkey [18]

* Not including the nominate subspecies

See also
  • List of snake genera, overview of all snake families and genera

Notes
  1. The elapids in the past were considered to have two subfamilies–the Elapinae made of terrestrial species and Hydrophiinae made of the marine species.[1] In 1997, Slowinski, Knight and Rooney found in their phylogenetic analysis using amino acid sequences from venom proteins, that the Australasian terrestrial species nested within Hydrophiinae. This led to removing the Australasian terrestrial species and placing them in the Hydrophiinae.[2][1] This has been support in subsequent recent genomic analyses, though these same studies also found the subfamily Elapinae to be paraphyletic in respect to the Hydrophiinae.[3][4][5] These studies have found coral snakes, cobras and mambas, kraits, and African gartersnakes forming successive outgroups to Hydrophiinae.[4][5] Since there are available clade names for these groups (with the exception of Elapsoidea), it is ideal to bring back the subfamilies Calliophiinae, Micrurinae, Najinae, and Bungarinae.

References
  1. Mattison C (2007). The New Encyclopedia of Snakes. Princeton University Press.
  2. Slowinski JB, Knight A, Rooney AP (December 1997). "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. 8 (3): 349–62. CiteSeerX 10.1.1.324.3013. doi:10.1006/mpev.1997.0434. PMID 9417893.
  3. Pyron RA, Burbrink FT, Wiens JJ (April 2013). "A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes". BMC Evolutionary Biology. 13: 93. doi:10.1186/1471-2148-13-93. PMC 3682911. PMID 23627680.
  4. Lee MS, Sanders KL, King B, Palci A (January 2016). "Diversification rates and phenotypic evolution in venomous snakes (Elapidae)". Royal Society Open Science. 3 (1): 150277. Bibcode:2016RSOS....350277L. doi:10.1098/rsos.150277. PMC 4736917. PMID 26909162.
  5. Figueroa A, McKelvy AD, Grismer LL, Bell CD, Lailvaux SP (2016). "A Species-Level Phylogeny of Extant Snakes with Description of a New Colubrid Subfamily and Genus". PLOS ONE. 11 (9): e0161070. Bibcode:2016PLoSO..1161070F. doi:10.1371/journal.pone.0161070. PMC 5014348. PMID 27603205.
  6. "Definition of 'elapid'". dictionary.com. Retrieved 2009-07-13.
  7. Chanhome L, Cox MJ, Vasaruchapong T, Chaiyabutr N, Sitprija V (June 2011). "Characterization of venomous snakes of Thailand". Asian Biomedicine. 5 (3): 311–28. doi:10.5372/1905-7415.0503.043 (inactive 2021-01-14).CS1 maint: DOI inactive as of January 2021 (link)
  8. Regional Office for Africa, World Health Organization (2010). "Handbook of Prevention and Clinical Management of Snakebites in Africa" (PDF). Retrieved April 25, 2019.
  9. Elapidae at the Reptarium.cz Reptile Database. Accessed 3 November 2008.
  10. Thomas S, Griessel E (Dec 1999). "LD50 Scores for various snakes". Archived from the original on 1 February 2012.
  11. de la Rosa G, Olvera F, Archundia IG, Lomonte B, Alagón A, Corzo G (August 2019). "Horse immunization with short-chain consensus α-neurotoxin generates antibodies against broad spectrum of elapid venomous species". Nature Communications. 10 (1): 3642. Bibcode:2019NatCo..10.3642D. doi:10.1038/s41467-019-11639-2. PMC 6692343. PMID 31409779.
  12. Slowinski JB, Keogh JS (April 2000). "Phylogenetic relationships of elapid snakes based on cytochrome b mtDNA sequences" (PDF). Molecular Phylogenetics and Evolution. 15 (1): 157–64. doi:10.1006/mpev.1999.0725. PMID 10764543.
  13. Williams D, Wüster W, Fry BG (December 2006). "The good, the bad and the ugly: Australian snake taxonomists and a history of the taxonomy of Australia's venomous snakes" (PDF). Toxicon. 48 (7): 919–30. doi:10.1016/j.toxicon.2006.07.016. PMID 16999982.
  14. "Elapidae". Integrated Taxonomic Information System. Retrieved 27 November 2006.
  15. The Hydrophiidae at Cyberlizard's home pages. Accessed [12 August] [2007].
  16. Scanlon J,Lee M, Archer M, 2002, Mid-Tertiary elapid snakes (Squamata, Colubroidea) from Riversleigh, northern Australia: early steps in a continent-wide adaptive radiation, Geobios 36 (2003) 573–601
  17. Nilson G, Rastegar-Pouyani N (2007). "Walterinnesia aegyptia Lataste, 1887 (Ophidia: Elapidae) and the status of Naja morgani Mocquard, 1905". Russian Journal of Herpetology 14: 7-14.
  18. Ugurtas IH, Papenfuss TJ, Orlov NL (2001). "New record of Walterinnesia aegyptia Lataste, 1887 (Ophidia: Elapidae: Bungarinae) in Turkey". Russian Journal of Herpetology 8 (3): 239-245.

Further reading
  • Goin CJ, Goin OB, Zug GR (1978). "Family Elapidae". Introduction to Herpetology (Third ed.). San Francisco: W.H. Freeman and Company. pp. 329–333. ISBN 0-7167-0020-4.CS1 maint: multiple names: authors list (link)
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.