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| Crotalus durissus|
Crotalus durissus is a venomous rattlesnake species found in Mexico and South America. The most widely distributed member of its genus, this species poses a serious medical problem in many parts of its range. 12 subspecies are currently recognized, including the typical form.
Grows to a maximum length of about 180 cm.
The body has an exceedingly rough appearance as the normal dorsal scale keels are accentuated into protuberances or tuberculations. This is most apparent on the scale rows to either side of the vertebral scales, with a decreasing intensity in the lower rows. The vertebral scales are about as prominently keeled as the fourth row down on the flanks (with the vertebral scales as the first row).
Found from Mexico (on the Atlantic side in Tamaulipas and Nuevo León, on the Pacific side in Michoacán) to Costa Rica (Guanacaste and the Meseta Central), including Belize, Guatemala, El Salvador and Nicaragua. There are also many isolated populations in northern South America, including Colombia, Venezuela, Guyana, Suriname, French Guiana and northern Brazil. Also occurs in Colombia and eastern Brazil to southeastern Peru, Bolivia, Paraguay, Uruguay, and northern Argentina (Catamarca, Córdoba, Corrientes, Chaco, Entre Rios, Formosa, La Pampa, La Rioha, Mendoza, Misiones, San Juan, San Luis, Santa Fe, Santiago del Estro and Tucumán). The type locality given is "America."
Bite symptoms are very different from those of Nearctic species, particularly in the southern parts of the range, due to the presence of neurotoxins (crotoxin and crotamine) that cause progressive paralysis. Bites from Brazilian specimens, notably C. d. terrificus, can result in impaired vision or complete blindness, auditory disorders, ptosis, paralysis of the peripheral muscles, especially of the neck, which becomes so limp as to appear broken, and eventually life-threatening respiratory paralysis. The ocular disturbances, which according to Alvaro (1939) occur in some 60% of terrificus cases, are sometimes followed by permanent blindness. Phospholipase A2 neurotoxins also cause damage to skeletal muscles and possibly the heart, causing general aches, pain and tenderness throughout the body. Myoglobin released into the blood results in dark urine. Other serious complications may result from systemic disorders (incoagulable blood and general spontaneous bleeding), hypotension and shock. Hemorrhagins may be present in the venom, but any corresponding effects are completely overshadowed by the startling and serious neurotoxic symptoms.
On the other hand, bites from subspecies in the northern parts of the range, such as C. d. durissus in Central America, are more like rattlesnake bites in the United States. Local symptoms may be severe, with pain, massive swelling, blistering and necrosis that often lead to physicians performing fasciotomies and in some cases amputations. Systemic effects involving hemostatic disturbances are rare, as are renal failure and neurotoxicity. Only the venom of newborn C. d. durissus contains crotoxin that is responsible for neurotoxic symptoms.
|Subspecies||Authority||Common name||Geographic range|
|C. d. cascavella||Wagler, 1824|
|C. d. collilineatus||Amaral, 1926|
|C. d. culminatus||Klauber, 1952||Southwestern Mexico from southern Michoacán to approx. the Isthmus of Tehuantepec.|
|C. d. cumanensis||Humboldt, 1833|
|C. d. dryinus||Linnaeus, 1758|
|C. d. durissus||Linnaeus, 1758|
|C. d. marajoensis||Hoge, 1966|
|C. d. ruruima||Hoge, 1966|
|C. d. terrificus||(Laurenti, 1768)|
|C. d. totonacus||Gloyd & Kauffeld, 1940||Northern Mexico.|
|C. d. trigonicus||Harris & Simmons, 1978|
|C. d. tzabcan||Klauber, 1952||Mexico in the Yucatán Peninsula south to northern Belize and northern Guatemala.|
- McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
- Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X.
- Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.
- Warrell DA. 2004. Snakebites in Central and South America: Epidemiology, Clinical Features, and Clinical Management. In Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.
- Crotalus durissus (TSN 563936). Integrated Taxonomic Information System. Accessed on 18 November 2006.
- Klauber LM. 1997. Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. University of California Press, Berkeley. ISBN 0-520-21056-5.
- Alvaro ME. 1939. Snake Venom in Ophthalmology. Am. Jour. Opth., Vol. 22, No. 10, pp. 1130-1145.