Lachesis (genus)

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Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Subfamily: Crotalinae
Genus: Lachesis
Daudin, 1803
  • Lachesis - Daudin, 1803
  • Trigonocephalus - Oppel, 1811
  • Trigalus - Rafinesque, 1815
  • Cophias - Merrem, 1820[1]

Common names: bushmasters.

Lachesis is a genus of venomous pit vipers found in the remote, forested areas in Central and South America.[1] Three species are currently recognized.[2]


Most adults measure less than 2.5 m in length, with 3.5 m being the likely maximum size. This makes them the longest venomous snakes in the Americas and the world's longest viperid snakes. There are many reports of larger specimens, but all are doubtful.[3]

The head is relatively smaller and more pointed in South American populations, while in Central America it is larger with a bluntly rounded snout. The rostral scale is more or less triangular and may be as wide or wider than it is high. There are 3/3 preoculars, with the upper being the largest. A suture separates the middle preocular from the supralacunal, while the lower preocular and the sublacunal are fused, forming a single elongated scale. The second supralabial is often fused with the prelacunal, forming the anterior border of the pit.[3]

The ground color in adult specimens is pinkish tan, orangish tan, reddish brown or yellowish, but this varies considerably. Subadults and juveniles generally have a darker ground color, but with a lighter dorsal pattern (medium to dark brown).[3]

Geographic range

Found in Central and South America.[1]


Members of this genus are perhaps the only New World pit vipers that lay eggs. The only other species in this part of the world that may do this is Bothrocophias colombianus. There are about 6-11 eggs in the average clutch and a maximum of 20, with females remaining coiled around the eggs during an incubation period that may last for 60-90 days depending on conditions and the (sub)species. Hatchlings are 34.5-48 cm in length and weigh 42.6-67 g.[3]


The reputation of this genus is undeserved, probably made up by people who thought that their large size also called for a formidable reputation. While certainly capable of delivering a lethal bite, it is no more capable of doing so than other species.[4]


Species[2] Authority[2] Subsp.*[2] Common name Geographic range[1]
L. melanocephala Solórzano and Cerdas, 1986 0 Black-headed bushmaster Costa Rica: Pacific versant of southeastern Puntarenas province from near sea level to about 1500 m.
L. mutaT (Linnaeus, 1766) 1 South American bushmaster South America in the equatorial forests east of the Andes: Colombia, eastern Ecuador, Peru, northern Bolivia, eastern and southern Venezuela, Guyana, Surinam, French Guiana and much of northern Brazil. It also occurs on the island of Trinidad.[5]
L. stenophrys Cope, 1875 0 Central American bushmaster In Central America it is found in the Atlantic lowlands of southern Nicaragua, Costa Rica and Panama, as well as the Pacific lowlands of central and eastern Panama. In South America it occurs in the Pacific lowlands of Colombia and northwestern Ecuador, the Caribbean coast of northwestern Colombia and inland along the Magdalena and Cauca river valleys.

*) Not including the nominate subspecies (typical form).
T) Type species.

Cited references

  1. 1.0 1.1 1.2 1.3 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).
  2. 2.0 2.1 2.2 2.3 Lachesis (TSN 209555). Integrated Taxonomic Information System. Accessed on 25 October 2006.
  3. 3.0 3.1 3.2 3.3 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.
  4. Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X.
  5. List of Snakes of Trinidad and Tobago at Republic of Trinidad and Tobago Biodiversity Clearing House. Accessed 6 November 2006.

Other references