Bothrops atrox — Overview

Barba Amarilla, Fer-de-lance, Common Lancehead learn more about names for this taxon


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Bothrops atrox

Bothrops atrox — known as the common lancehead, fer-de-lance, and barba amarilla[2] — is a species of pit viper found in the tropical lowlands of northern South America east of the Andes.[1] No subspecies are currently recognized.[3]


A terrestrial species, adults usually grow to a total length 75–125 cm (about 30-50 inches) and are moderately heavy-bodied. Reports of the maximum size are not clear, as this species is often confused with B. asper. Soini (1974) mentioned of a series of 80 specimens collected in northeastern Peru, the largest was a female of 138.8 cm (4.55 ft). The largest specimen measured by Campbell and Lamar (2004) was a female with a total length of 162 cm (5.31 ft).[2]

The scalation includes 23-29 (usually 23-25) rows of dorsal scales at midbody, 169-214 and 177-214 ventral scales in males and females, respectively, 52-86 (usually 75 or fewer) subcaudal scales in males, which are usually divided, and 47-72 subcaudals in females. On the head, the rostral scale is about as high, or slightly higher, than it is wide. There are three to 11 (usually five to 9) keeled intersupraocular scales, seven to 13 (usually eight to 11) sublabial scales and six to 9 (usually seven) supralabial scales, the second of which is fused with the prelacunal to form a lacunolabial.[2]

Bothrops atrox in Arima, Trinidad and Tobago.

The color pattern is highly variable, including a ground color that may be olive, brown, tan, gray, yellow, or (rarely) rusty. The body markings are highly variable, as is the degree of contrast: in some specimens the pattern is very well defined, while in others it may be virtually absent. In general, however, the body pattern consists of a series of dorsolateral blotches, rectangular or trapezoidal in shape, which extend from the first scale row to the middle of the back. These blotches may oppose or alternate across the midline, often fusing to form bands. They also have pale borders, which in some cases may be prominent, and may be invaded from below by tan or gray pigment, occasionally dividing them into pairs of ventrolateral spots. The belly may be white, cream or yellowish gray, with an increasing amount of gray to black mottling posteriorly that may fade again under the tail. The head usually does not have any markings other than a moderately wide postocular stripe that runs from behind the eye back to the angle of the mouth. The iris is gold or bronze, with varying amounts of black reticulation, while the tongue is black.[2]

Common names[edit]

Common names include lancehead, fer-de-lance, and barba amarilla.[2]

The Spanish common name barba amarilla (yellow beard), an allusion to the pale yellow chin color, is also used in English. In Colombia, it is known as mapaná (Llanos of Vichada) and talla equis. In Guyana and Suriname, it is called labaria[4] or labarria.[5] In Peru, it is called aroani (Yagua), cascabel (juveniles), ihdóni (Bora), jergón, jergona, jergón de la selva, macánchi (Alto Marañón), machacú, marashar and nashipkit (Aguaruna names). In Venezuela, it is called mapanare. The jergón name[2] is an allusion to the x-like markings of the color pattern. In Ecuador, these x-like markings have led to the snake simply being referred to as equis (the Spanish pronunciation of the letter 'x'). In Trinidad it is known as mapepire balsain.[6] In Bolivia it is called Yoperojobobo.

Geographic range[edit]

This species is found in the tropical lowlands of South America east of the Andes, including southeastern Colombia, southern and eastern Venezuela,the island of Trinidad (although there is some confusion of the systematics of this population), Guyana,[7] Suriname, French Guiana, eastern Ecuador, eastern Peru, Panama, northern Bolivia and the northern half of Brazil.[1] The type locality is listed as "Asia", which is obviously a mistake. Schmidt and Walker (1943:295) proposed this be corrected to "Surinam".[1]


Despite the vast destruction of rain forests, it is amongst the most numerous of pit vipers and is not endangered. In Trinidad, it prefers wet forests from sea level to 940 m.[8]


Although generally terrestrial, it is also an excellent swimmer and even climbs trees when necessary to reach prey. Generally nocturnal, it may forage at any time of the day, though, if necessary. These snakes are also easily agitated.


The main diet includes mostly small mammals and birds, but also frogs and lizards. Larger prey is struck and released, after which it is tracked down via its scent trail.


Bothrops atrox can lay up to 80 eggs at once. Adults breed year-round. After mating, females with developing embryos travel in and out of sunlight to keep themselves and the embryos at a constant temperature. In equatorial regions, the gestation period is about three to four months, with an average of 60 young per litter. At birth, the young are about 30 cm (12 inches) in total length, more brightly colored than adults, and have yellow or beige tails.


These snakes are known to search for rodents in coffee and banana plantations. Workers there are often bitten by the snakes, which can lie camouflaged for hours, nearly undetectable, and strike with high speed.

Their venom consists mostly of hemotoxins. They are much feared because their venom is particularly lethal and fast acting. Presently, treatment is usually possible if the victim receives medical attention soon enough.[9] Commonly, bites from this snake cause symptoms including nausea, blackouts, and paralysis. In almost all cases, temporary and sometimes permanent loss of local or 'short term' memory were reported. Extended hospital stays, as well as weight loss of up to 15 pounds, have also been reported. Venom yield averages 124 milligrams (1.91 gr), although it may be as much as 342 milligrams (5.28 gr). The enzyme reptilase (batroxobin), derived from this snake's venom, is used in modern medical laboratories to measure fibrinogen levels and blood coagulation capability. The test is considered to be a replacement for thrombin time, and is used when heparin is present in the sample. The enzyme is unaffected by heparin.[10]


The taxonomy of this species is controversial; it may include B. leucurus and B. moojeni, and some of its populations are sometimes said to be separate species. B. asper was formerly included in this species, but most authorities now consider it distinct.

See also[edit]


  1. ^ a b c d McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
  2. ^ a b c d e f 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.
  3. ^ "Bothrops atrox". Integrated Taxonomic Information System. Retrieved 6 November 2006. 
  4. ^ "Environmental Impact Assessment- Buddy's International Hotel" (pdf). Cemco, Inc. 2006. p. 47. Archived from the original on 2007-08-10. Retrieved 2006-11-10. 
  5. ^ "Venomous Snakes of Guyana". Iwokrama International Centre for Rain Forest Conservation and Development. Retrieved 2006-11-10.  Includes a photograph.
  6. ^ Cote ce Cote la: Trinidad & Tobago Dictionary, p. 75. John Mendes. (1986) Arima, Trinidad.
  7. ^ Cole, C.J., C.R. Townsend, R.P. Reynolds, R.D. MacCulloch and A. Lathrop (2013). "Amphibians and reptiles of Guyana, South America: Illustrated keys, annotated species accounts, and a biogeographic synopsis". Proceedings of the Biological Society of Washington 125: 317–620. 
  8. ^ Herklots GAC. 1961. The Birds of Trinidad and Tobago. Collins, London, p. 10.
  9. ^ Stidworthy J. 1974. Snakes of the World. Grosset & Dunlap Inc. 160 pp. ISBN 0-448-11856-4.
  10. ^ Heimann, D; V Wolf; H Keller (June 1979). "[The use of reptilase for electrophoresis of heparinized plasma (author's transl)]". Zeitschrift für klinische Chemie und klinische Biochemie [Journal of Clinical Chemistry and Clinical Biochemistry]. 17 (6): 369–372. PMID 458385. Retrieved 2009-10-06. 

Further reading[edit]

  • Hays WST, Conant Sheila. 2007. Biology and Impacts of Pacific Island Invasive Species. 1. A Worldwide Review of Effects of the Small Indian Mongoose, Herpestes javanicus (Carnivora: Herpestidae). Pacific Science 61 (1): 3–16.
  • Linnaeus, C. 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Tenth Edition. Holmiæ. Stockholm. 824 pp. (Coluber atrox, p. 222.)
  • Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X.
  • O'Shea M. 2005. Venomous Snakes of the World. Princeton, New Jersey: Princeton University Press. 160 pp. ISBN 0-691-12436-1.


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