The Brazilian wandering spiders (Phoneutria spp.), armed spiders (“aranhas-armadeiras”, as they are known in Portuguese), or banana spiders (not to be confused with the relatively harmless species of the genus Nephila) are a genus of aggressive and highly venomous spiders found in tropical South and Central America. These spiders are members of the Ctenidae family of wandering spiders.
The Brazilian wandering spiders appeared in Guinness World Records 2010 as the world’s most venomous spider.
The genus Phoneutria (Greek for “Murderess”) contains eight scientifically described species. The Brazilian wandering spiders can grow to have a leg span of up to 13–15 cm (4–5 in). Their body length ranges from 17 to 48 mm (0.7–1.9 in). The genus is distinguished from other related genera such as Ctenus by the presence of dense prolateral scapulae on the pedipalp tibiae and tarsi in both sexes. Phoneutria are especially easily confused with Cupiennius, in which some species (such as the recently described C. chiapanensis) also have red hairs on the chelicerae.
Wandering spiders are so-called because they wander the jungle floor at night, rather than residing in a lair or maintaining a web. During the day they hide inside termite mounds, under fallen logs and rocks, and in banana plants and bromeliads. P. nigriventer is known to hide in dark and moist places in or near human dwellings.
P. nigriventer mates during the dry season from April to June, which leads to frequent observations of the species during this time.
They have a distinctive defensive display in which the body is lifted up into an erect position, the first two pairs of legs are lifted high (revealing the conspicuous black-striped pattern on their underside), while the entire spider sways from side to side with hind legs in a cocked position.
Phoneutria are found in forests from Costa Rica throughout South America east of the Andes into northern Argentina, including Colombia, Venezuela, the Guianas, Ecuador, Peru, Bolivia, Brazil and Paraguay. Two species (P. reidyi and P. boliviensis) are found from southern Central America to the Amazon region, while one species (P. fera) is restricted to the Amazon. The remaining species are restricted to Atlantic Forest of Argentina, Paraguay and Brazil, including forest fragments in the Cerrado (savannah). In Brazil, Phoneutria is only absent in the northeastern region north of Salvador, Bahia.
Phoneutria has been introduced to Chile and Uruguay.