Bothrops atrox

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.

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. 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 In Bolivia, it is called Yoperojobobo. In Brazil, the common names are jararaca or Jararaca-do-norte. The name fer-de-lance comes from French, meaning, "head of a lance", "spearhead", or literally "lance iron".

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 . Suriname, French Guiana, eastern Ecuador, eastern Peru, Panama, northern Bolivia, and the northern half of Brazil. Along with Bothrops caribbaeus and B. lanceolatus, it is one of three Bothrops species found in the West Indies.

Behavior

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.

Feeding

Their main diet includes mostly small mammals (such as rodents and opossums) and birds, but also frogs, lizards, smaller snakes, fish, crayfish, centipedes, and tarantulas. Larger prey is struck and released, after which it is tracked down by its scent trail.

Reproduction

Bothrops atrox can give live birth to up to 80 offspring 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 in total length, more brightly colored than adults, and have yellow or beige tails.

Three species of the Neotropical pit viper Bothrops atrox group were confirmed to undergo facultative parthenogenesis on the basis of captivity information and by the use of molecular markers (heterologous microsatellites). Infertile eggs, non-viable ova and malformed offspring were frequent in those cases. As a result, clotting assays such as prothrombin time and aPTT will be highly disturbed. Spontaneous recovery from coagulopathy is seen 14 to 30 hours after bite according to a study performed in French Guiana. A Mexican polyvalent antivenom was tested, but had no effect on it. B. atrox venom can result in several systemic and local symptoms, such as severe bleeding, kidney failure, abnormal clotting, blisters, and necrosis. The bite can also result in hemorrhage in the central nervous system, which leads to sequelae and even death. In a case reported in the Brazilian Amazon, symptoms such as pain and ecchymoses, headaches, nausea, vomiting, diarrhea, hypertension, and blood incoagulability were reported, the patient died of stroke, even after administration of the antivenom. The common lancehead has an LD<sub>50</sub> of 1.1 to 4.9 mg/kg; the venom of juveniles is more inflammatory, lethal, and hemorrhagic, and kills more quickly than that of adults. People bitten by neonates are more likely to develop coagulopathy.

Venom yield averages , although it may be as much as . 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.