In the city of Porto in northern Portugal, the Chilean recluse spider (Loxosceles laeta) — one of the most venomous spider species in the world — has been detected for the first time on the Iberian Peninsula. Scientists emphasize that due to its secretive lifestyle, the risk to the public remains low. This was reported by Euronews, writes UNN.
Details
In an interview with the publication, one of the authors of the discovery, entomologist at the Museum of Natural History and Science of the University of Porto, José Manuel Grosso-Silva, stressed that there is no reason for panic.
"The likelihood of people encountering this spider or it biting them is low," the researcher noted.
In a scientific article by biologists Francisco Gil and José Manuel Grosso-Silva, dedicated to the first finding of this species on the Iberian Peninsula, it is stated:
"This is a timid species that is not prone to biting, however, its bite can cause serious skin damage, often leading to necrotic lesions."
The Chilean recluse spider is a native inhabitant of western South America, primarily Chile, and also occurs in Brazil and Argentina. Through international trade, it has gradually spread far beyond its natural range.
The first specimen was accidentally found on September 10, 2025, on the wall of a building in the Campo dos Mártires da Pátria district in Porto. It was a male. A second male was found dead on January 10, 2026, on a glue trap that had not been set for this species.
Despite the appearance of the new species, another venomous representative of this genus has lived in Portugal for several decades — the Mediterranean recluse spider (Loxosceles rufescens), which is widespread throughout the country.
"We do not know whether this new species is limited only to Porto or has already spread much wider. Since the Chilean recluse spider can easily be confused with the Mediterranean one, it is quite possible that some photographs thought to be images of the latter actually show the new species," the biologist explains.
The main difference between these two species lies in the structure of the males' pedipalps — paired appendages near the mouthparts that perform sensory and reproductive functions and are used to transfer sperm during mating.
In appearance and behavior, both species are very similar.
"They have a uniform brown coloration, do not camouflage among vegetation, and do not weave typical catching webs. They create webs on walls, in corners and dark hidden places, and are most active at night," explains José Manuel Grosso-Silva.
Bites from such spiders can vary in severity — from mild cases to very severe ones, including rare fatalities.
"The risk exists, but in my opinion, it is small, so I do not want to contribute to panic or excessive anxiety," the researcher emphasizes.
The bite causes necrosis
In 2023, a case of loxoscelism — a syndrome caused by the venom of spiders of the genus Loxosceles — was registered in Portugal. It was caused by the bite of a Mediterranean recluse spider.
The scientific journal SPMI Case Reports, published by the Portuguese Society of Internal Medicine, described the case of a 48-year-old woman who was bitten by a spider in a city park.
After the bite on the back of her head, initially only swelling appeared without pain. However, within the next day, her condition deteriorated sharply: severe headache, malaise, fever, fatigue developed, and necrosis with redness developed at the bite site. Subsequently, skin peeling appeared around the eyes, on the buttocks, thighs, lips, and oral mucosa.
After 16 days, the woman was discharged from the hospital without residual symptoms.
New species are appearing more and more often
Currently, more than 300 alien species of insects have already become established in Portugal, most of which were accidentally introduced by humans through international transportation of goods.
"We are increasingly changing the environment. We deliberately import many plants, which often carry insects that we had no intention of bringing in," the researcher explains.
He cites the example of the Asian hornet, which entered Europe through France along with a shipment of Chinese bonsai.
In addition, urbanization, large-scale eucalyptus plantations, and vast agricultural monocultures, particularly of corn, are reducing the natural habitats of many species, which alters ecosystems and facilitates the emergence of new organisms.
Global warming, which is manifesting particularly rapidly in Europe, may also contribute to the reproduction and spread of exotic species.
"We do not yet know how the situation will develop on the Iberian Peninsula. This needs to be carefully monitored over the coming years," says José Manuel Grosso-Silva.
Presence of the Chilean recluse spider in Europe
The first finding of this species in Europe was recorded back in 1972 in a building of the faculties of zoology and genetics at the University of Helsinki in Finland.
It is believed that the spider was accidentally brought in by people, after which it settled inside the building, where it was warm enough to survive, as the Finnish climate is unsuitable for it in the open environment.
In 2025, a specimen of this species was also found in the basement of the Eberhard Karls University of Tübingen (Germany).
There are also reports of the possible presence of the Chilean recluse spider in Italy, but the original source of this information is no longer available, so this data remains unconfirmed.