Venomous Chilean Recluse Spider Recorded in Portugal for the First Time

Researchers at the University of Porto have recorded the first confirmed appearance of the Chilean recluse spider (Loxosceles laeta) on the Iberian Peninsula. The paper was published in 2026 in the journal Arquivos Entomolóxicos.

The first spider was discovered on September 10, 2025, on a wall in the historic centre of Porto, in the Campo dos Mártires da Pátria. A second case was recorded on January 10, 2026 — another male was found dead on a sticky trap in one of the city's buildings. The device was not intended to catch spiders of this species, but it enabled continued study of its potential spread.

Loxosceles laeta is a species from South America, widespread in Chile, Peru, Argentina, and Brazil. Despite its relatively small size (8–30 millimetres including the legs), this spider is dangerous to humans. The venom of the Chilean recluse spider has a necrotising effect and often causes skin lesions. In severe cases, systemic complications are possible.

The spider leads a secretive life, avoids light, and hides in crevices, cracks in walls, and hard-to-reach places. The likelihood of accidentally encountering it is low, and it bites only on direct contact or when threatened. Scientists assess the risk to the population as low.

The researchers suggest that the Chilean spider's appearance in Porto is linked to international freight transport. The paper's authors, Francisco Gil and José Manuel Grosso-Silva, stress that two separate cases do not yet allow one to speak of an established population in the city. However, they don't rule out the species' hidden presence in hard-to-reach urban spaces.