Two Male Chilean Recluse Spiders Found in Porto

Two male specimens of the Chilean recluse spider, Loxosceles laeta, were found in Porto, Portugal. The first was spotted on a wall in Campo dos Mártires da Pátria on 10 September 2025. The second was collected dead from a sticky trap on 10 January 2026.

José Manuel Grosso-Silva, an entomologist at the Natural History and Science Museum of the University of Porto, said the species is shy and not inclined to bite. Its bite can cause significant skin damage, frequently resulting in necrotic lesions. Euronews reported the details from a study by biologists Francisco Gil and Grosso-Silva.

The spider is native to western South America and has been recorded in Brazil and Argentina. It reached Europe through international trade. The first European record dates to 1972 at the University of Helsinki in Finland.

A specimen was also identified in the basement of Eberhard Karl University of Tübingen in Germany in 2025. An unconfirmed record exists for Italy. Loxosceles rufescens, the Mediterranean recluse spider, has lived in Portugal for several decades and is widely distributed.

In 2023 a 48-year-old woman developed loxoscelism after a bite in an urban park. She experienced swelling, headaches, malaise, feverishness, fatigue and necrosis with erythema at the bite site over 24 hours. The two species are uniformly brown, build webs on walls and in dark corners, and are more active at night.

The main morphological difference is in the males' pedipalps. Grosso-Silva said it is not known whether the new species is confined to Porto or already more widespread, and that photographic records labelled as the Mediterranean recluse may actually show Loxosceles laeta.

Grosso-Silva added that the risk appears low but the situation should be monitored over the coming years as humans continue to change the environment.