''Bothrops alcatraz'', also known as the Alcatrazes lancehead, is a

pitviper The Crotalinae, commonly known as pit vipers,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . crotaline snakes (from grc, κρόταλον ''krotalon'' castanet), or pit adders, are a subfa ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

found only on the

Alcatrazes Islands Alcatrazes is a Brazilian archipelago, located some 35 km south of São Sebastião, in the northern coast of the State of São Paulo, one hour away by boat, approximately. It is protected by the largest marine integral conservation unit of ...

off the coast of southeastern

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. No subspecies are currently recognized. Like all pit vipers, it is venomous.

Description

Grows to a maximum size of 46.2/50.5 cm for males/females. Its small size and relatively large eyes are considered paedomorphic (juvenile) characteristics. Until 15,000 years ago, only common '' Bothrops'' lived by the island, which was at that time still connected to the continent due to the receded sea waters. When the sea rose back again (with the end of the last glacial period) and the mountain returned to its archipelago status, the ''Bothrops'' that became isolated there quickly fed on all available rodents, which are its main food. They ended up resorting to cockroaches and ''

scolopendra ''Scolopendra'' (through Latin from Greek , ''skolopendra'') is a species-rich genus of large tropical centipedes of the family Scolopendridae. Description The genus ''Scolopendra'' contains many species of centipedes found across the world' ...

'' and, due to their much smaller nutritional value, the snakes slowly shrunk their size until they couldn't grow beyond 50 cm – a process known as

allopatric speciation Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...

Geographic range

Found only on Ilha Alcatrazes, 35 km off the coast of

São Paulo São Paulo (, ; Portuguese for 'Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the GaWC a ...

, southeastern

. This island, which has a total area of only 1.35 km², is one of four islands than make up the Alcatrazes Archipelago. The type locality given is therefore the same: "Alcatrazes Island, (24°06'S, 45°42'W), São Sebastião, São Paulo, Brazil".

Habitat

Described as "low Atlantic Forest vegetation". The highest point on island is 266 m.

Conservation status

This species is classified as vulnerable on the

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

Red List. Although ''Bothrops alcatraz''t is relatively abundant on Alcatrazes, its range is very small (less than 1.35 km²), making it vulnerable to stochastic events. Previously, the island was used as a Naval target practice area.

Cited references

{{Taxonbar, from=Q2911758 alcatraz Snakes of Brazil Endemic reptiles of Brazil Reptiles described in 2002 Taxonomy articles created by Polbot