Golden Lancehead

The golden lancehead (Bothrops insularis) is an extremely venomous pit viper species in the subfamily Crotalinae of the family Viperidae. The species is found exclusively on the island of Ilha da Queimada Grande, off the coast of São Paulo state, in Brazil. The common name of the species refers to the light yellowish-brown color of its underside and for its lance-like head shape that is characteristic of the genus Bothrops. No subspecies of B. insularis are recognized as being valid. It is one of the most venomous snakes in Latin America.

Physical morphology

Size and appearance

Usually, B. insularis grows to a total length (including tail) of 70 to 90 cm (28 to 35 in), but it is known to reach a total length of 118 cm (46 in). Its color pattern consists of a pale yellowish-brown ground color, overlaid with a series of dorsal blotches that may be triangular or quadrangular, broad or narrow, and alternating or opposite along the dorsal median. In captivity, this yellowish color often becomes darker, which may be the result of poor circulation caused by ineffective thermoregulation. A banded pattern results when the pattern is opposite. The head lacks a well-defined postorbital stripe. The belly is a uniform pale yellow or cream.

The name "lancehead" refers to the distinctive head shape of all snakes in the genus Bothrops, which is somewhat elongated and comes to a point at the nose. B. insularis also has a longer tail than its closest relative, B. jararaca, which is most likely an adaptation to help the snake maneuver through the trees, and to eat larger prey, such as birds, from a younger age.

Venom

Because of the isolated habitat of B. insularis, and the lack of mammal prey species, the venom of B. insularis has evolved to be adapted to the prey species of the island, primarily native ectotherms, arthropods, and migrating birds. As a result, its venom is more potent towards these groups than mammals, and becomes more potent as the snake matures. Chemical analysis of the venom of B. insularis suggests that it is five times as potent as that of B. jararaca and is the fastest-acting venom in the genus Bothrops.

Because B. insularis is only found in an area uninhabited by humans, an official report of a human being bitten by one has not been made, but other lanceheads are responsible for more human mortality than any other group of snakes in either North or South America. Ludwig Trutnau reports four human envenomations, three of which were fatal. The mortality rate for lancehead envenomations is 0.5–3.0% if the patient receives treatment and 7.0% if the patient does not receive treatment. The effects of envenomations by golden lanceheads include swelling, local pain, nausea and vomiting, blood blisters, bruising, blood in the vomit and urine, intestinal bleeding, kidney failure, hemorrhage in the brain, and severe necrosis of muscular tissue.

Reproduction