Bothrops insularis, commonly known as the golden lancehead,[3] is a species of extremely venomous pit viper 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.
[3] 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.
[3] 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.
[6] 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.
[5] The quality of its habitat continues to decline due to vegetation removal by members of the Brazilian Navy, who maintain the lighthouse on the island.
The golden lancehead is thought to descend from a population of B. jararaca that became isolated on Queimada Grande, which was connected to the South American mainland during the last glacial period, after a major sea-level rise at the beginning of the Holocene.
No mammals are native to the island Queimada Grande, which has undoubtedly had a profound impact on the evolution of the golden lancehead.
[3] In Campbell and Lamar's 2004 accounts of the venomous reptiles of Latin America, no mention was made of any predators that could potentially prey on an adults of B. insularis, but the list of animal species provided by Duarte et al. includes several species of birds, spiders, millipedes, and various lizards that inhabit the island, which could potentially be predators of young snakes.
[5] Other fauna, such as frogs, lizards, and birds, on the island eat invertebrates, but because insects are so plentiful in ecosystems, they may not be a limiting resource.
The golden lancehead is known to suffer from flukes (specifically Ochetosoma heterocoelium) in its mouth cavity, as well as to carry the hard-bodied tick Ambylomma rotundatum.
[5] Because of these problems, as well as overharvesting by overzealous scientists, Duarte et al. wrote that it is "very hazardous to assume that this is an invulnerable snake".
[18] Associated with the heavy inbreeding of B. insularis is the occurrence of "intersexes", individuals born with both a hemipenis and female reproductive parts.
[5] In addition to intersexes, when compared to its mainland relative B. jaracara, B. insularis has been found with reduced fecundity in females, and high levels of mutations in male sperm, thought to be a product of heavy inbreeding.
[18] As of 2019, snake expert Bryan Fry reported in an interview with 60 Minutes Australia that the migratory birds that B. insularis depends upon were visiting less due to deforestation on the Brazilian mainland.
[20] Considering the presence of potential prey susceptible to caudal luring,[20] though, and the opportunistic nature of B. insularis,[5] observing this behavior would not be surprising.