Spiders of the Falkland Islands 31 was published in May 2025, the latest in a series of papers describing the spiders of the islands. The first two papers covered the family Linyphiidae, (Money spiders), a worldwide family of small, unobtrusive spiders. There are 19 species on the islands, the largest being about 5mm body length, while most species are less than 2mm.
In contrast to the global Linyphiidae, the two families covered in the latest paper are exclusively southern hemisphere, with species from South America, Africa and Australasia. Family Orsolobidae, (Goblin spiders) are represented by 2 species, both found only on the Falklands. Indeed, as Falklandia rumbolli is the only species in its genus, both genus and species are endemic.
Falklandia rumbolli was first described in 1974 from specimens taken by Mauricio Rumboll on a collecting trip in 1972, remembered by some on the islands. I found unidentified specimens in the Natural History Museum, London, collected on West Falkland in 1952 by Kay McCallum and on East Falkland in 1961 by Ian Strange, but at the time they went undetected as a new species. It is a medium sized spider, notable for only having 6 eyes (most spiders have 8), widespread on the islands and found in a range of habitats, though mainly in Tussac and coastal communities.
Osornolobus otariorum from Box Island, 2008.
South Atlantic Invasive Species Project
The single species of Mecysmaucheniidae (Trap-jaw spiders) found here, Mecysmauchenius segmentatus, is found across the southern cone of South America. While less exclusive than the orsolobid species, it is notable for its exotic appearance and its remarkable history. The larger group of spiders this species belongs to, the superfamily Palpimanoidea, was first described from Eocene Baltic amber in 1854, decades before the first living species was found in Madagascar in 1881; it is a “living fossil”. The oldest known member of the superfamily was found in Jurassic sediments in China, making it one of the oldest spider groups.
Osornolobus otariorum is a new species, found only on the Falkland Islands, though it’s genus is found across southern South America, mainly in Chile. It is smaller than Falklandia, half Falklandia’s size at about 3mm body length and with a purple striped abdomen, contrasting with Falklandia's plain appearance. The species name otariorum means “from the sea lions”, commemorating the first specimen I found, on Sea Lion Island.
The two Goblin spider species have similar habitat preferences, commonest in Tussac, but Osornolobus otariorum is found in a wider range, including in diddle-dee (Empetrum rubrum). Both species are found across the archipelago.
Mecysmauchenius segmentatus from Pitt Island, November 2008.
South Atlantic Invasive Species Project
Mecysmauchenius segmentatus is a medium sized spider, about 5mm long, living almost exclusively in Tussac, where it hunts, often for other spiders, in the skirts and litter. It is widespread across the islands, probably present wherever there is tusscac. Its unusual appearance with large, strong jaws and raised eye region make it distinct from all other Falkland spiders.
Part 3 of the Spiders of the Falkland Islands is about the halfway point of the planned account, with 22 species covered and 24 to go2. The remaining species include 6 previously unknown species, and should confirm the Falkland’s place as an important area for spider diversification, and will add to our understanding of the unique spider assemblage of the extreme south of South America.
1 Lavery, A. H. & Snazell, R. G. (2025). The spiders of the Falkland Islands 3: Mecysmaucheniidae and Orsolobidae (Araneae). Arachnology 20: 12-24.
2 Lavery, A. H. (2017). Annotated checklist of the spiders, harvestment and pseudoscorpions of the Falkland Islands and South Georgia. Arachnology 17: 210-228.
