Bothrops atrox — also known as the common lancehead, fer-de-lance, barba amarilla and mapepire balsain — is a highly venomous pit viper species found in the tropical lowlands of northern South America east of the Andes, as well as the Caribbean island of Trinidad. No subspecies are currently recognized. Taxonomy The common lancehead was one of the many reptile and amphibian species described by Carl Linnaeus in the landmark 1758 10th edition of his Systema Naturae, where it was given the binomial name Coluber atrox. 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. Names Common names include lancehead, fer-de-lance, barba amarilla, and mapepire balsain, among others. The Spanish common name barba amarilla (yellow beard), an allusion to the pale yellow chin color, is also used in English. In Venezuela, it is called mapanare. In Colombia, it is known as mapaná (Llanos of Vichada) and talla equis. In Guyana and Suriname, it is called labaria or labarria. 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). The name jergón is an allusion to the x-like markings of the color pattern. In Ecuador and Panama, these x-like markings have led to the snake simply being referred to as equis (the Spanish name of the letter 'x'). In Trinidad it is known as mapepire balsain. In Bolivia it is called Yoperojobobo. In Brazil the common names are Jararaca or Jararaca-do-norte. Description 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 . The largest specimen measured by Campbell and Lamar (2004) was a female with a total length of . 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