Brazilian Wandering Spider

The genus Phoneutria (Greek for “Murderess”) contains eight similar scientifically described species. The Brazilian wandering spiders can grow to have a leg span of up to 10-13 cm (4-5 in). Their body length ranges from 17 to 48 mm (0.7-1.9 in).^[2] The genus is distinguished from other related genera such as Ctenus by the presence of dense prolateral scopulae on the pedipalp tibiae and tarsi in both sexes.^[2] 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.

Danger to humans

Phoneutria has a highly venomous bite. This genus includes some of the relatively few species of spiders known to present a threat to human beings.

These spiders are notorious both because of their toxic venom, and because they are not reluctant to attack people who appear threatening. Of the eight described species, P. nigriventer and P. fera most frequently receive mention in mass-media publications. P. nigriventer is the species responsible for most cases of venom intoxication in Brazil because it commonly is found in highly populated areas of south-eastern Brazil, such as the states of São Paulo, Minas Gerais, Rio de Janeiro and Espírito Santo. The species P. fera is native to the northern portion of South America in the Amazon of Brazil, Venezuela, Ecuador, Peru and the Guyanas.

Recent studies suggest that these spiders only inject venom in approximately one-third of their bites and may only inject a small amount in another third. However, research in this area is hindered by the difficulty of identifying particular species.

Bites from these spiders may result in only a couple of painful pinpricks, or may involve full-blown envenomation; but in all cases, people bitten by a Phoneutria, or any Ctenid, should seek immediate emergency treatment, as the venom can be life threatening. P. fera and P. nigriventer are the two most commonly implicated as the most virulent of the Phoneutria spiders. Phoneutria not only has a potent neurotoxin, but is reported to have one of the most excruciatingly painful envenomations of all spiders, because of its high concentration of serotonin.

via [wikipedia]