Loxosceles similis, is a species of a venomous recluse spider endemic to South America.

[2] Although not very well known, it is possible like other recluse spiders, that this species feeds on small insects, has nocturnal habits and is not aggressive.

[3] This species occurs in Brazil, in Pará, Minas Gerais, São Paulo, Mato Grosso do Sul and Bahia.

[4][5] A recent study on the characterization of the venom of this species showed that its biological effects have an intensity similar to that of Loxosceles laeta, Loxosceles intermedia and Loxosceles gaucho, an experimental study with rabbits injected with 0.5 μg (500 nanograms) of the venom resulted in severe edema, diffuse heterophilic inflammatory infiltrate, perivascular heterophilic infiltrate, thrombosis in all layers of the dermis, fibrinoid necrosis of the arteriolar wall, cutaneous muscle necrosis and dermal hemorrhage.

It is concluded that L. similis venom induces apoptosis of endothelial cells.