In the UK Overseas Territory of St Helena, two new species of spider have just been discovered. This brings the number of species that are unique to the South Atlantic island to a whopping 507. But it is possible that both these newly discovered spiders are already extinct.
The Christy Jo goblin spider (Ischnothyreus christyjoae), a spider with thick abdominal armour that helps protect it against predators, was discovered by Dr Danni Sherwood, an arachnologist. She’d been combing through museum collections, and when Dr Sherwood compared the goblin spider specimen with similar species, she found that the genitalia were completely unique – a giveaway that this was a new species.
“I discover new species both in the wild and in museums all the time, so it is somewhat routine,” Dr Sherwood tells BBC Wildlife, but she adds that these discoveries never lose their sparkle.
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Dr Sherwood also discovered the Martina miniscule spider (Anapistula martinae) in a museum collection. This spider is truly tiny at less than half a millimetre long – that’s less than the space between two letters in a standard Word document.
The miniscule spider has no eyes, and is the first eyeless spider known to live in St Helena. Surprisingly, it is not a cave-dweller. This is unusual, because eyeless species usually evolve in lightless environments, such as underground or in the deep, dark depths of caves.
“We are not quite sure about its lack of eyes,” Dr Sherwood says. “It could be that it occurs in crevices in rocks, or something entirely else has happened.”
Unfortunately, the goblin spider and the miniscule spider have not been observed in the wild for over 30 years. This suggests that they are either rare or already extinct, possibly succumbing to deforestation or competition from invasive species. Both these threats have put a lot of pressure on St Helena’s unique species and ecosystems.
The discovery of species in museum collections, only to find that they are already extinct, is becoming an all-too-common story. But hope is not lost for the Christy Jo goblin spider and the Martina miniscule spider. They may still be lurking somewhere in St Helena, and Dr Sherwood hopes that she and her colleagues will be able to go in search of them soon.
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Top image: St Helena in the Atlantic Ocean. Credit: Getty
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