A duo of marooned pirate spiders were discovered on a remote tropical island within the Atlantic Ocean.

spider web
(Photo: Pixabay / Adina Voicu )

New Pirate Spider Species Discovered

The two new pirate spider species live up to their name, which refers to how they violently conquer other spiders' webs and kill the occupants of these webs.

They were previously confused for another species that is closely related to it. For decades, they have been living on St. Helena. Now, as they are both newly recognized, it is hoped that the species could offer more impetus when it comes to preserving the threatened cloud forest of the island.

The discovery was noted in the "Two new sympatric species of the pirate spider genus Ero C.L. Koch, 1836 from the cloud forest of Saint Helena Island, South Atlantic Ocean (Araneae: Mimetidae)" study. Danni Sherwood, the study's lead author, shares that their work revealed the existence of the two spiders in the cloud forest. However, for more than 40 years, they were believed to be a typical single species that could be spotted in various parts of the world.

Close examination of the spiders offered initial hints that they belonged to a different species. Initially thought to be an Ero aphana pirate spider, it turned out to be an entirely different species.

Ero lizae has two structures at the back of its body that resemble spikes. On the other hand, Ero natashae is notably smaller. DNA evidence also helped prove that the spiders belonged to their own species. They used methods made for ancient DNA to get the genetic material from Ero lizae's two legs. The genetics of the spider revealed that it was different from Ero aphana, implying that they did not belong to the same species.

Such information gave the researchers confidence to formally describe the two new pirate spider species from specimens at London's Natural History Museum and Belgium's Royal Museum of Central Africa.

Sherwood explains that on top of having intriguing morphology, the spiders have type localities in one of the world's most distinct and threatened habitats, the Saint Helenian cloud forest.

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Saint Helena Cloud Forest

St. Helena is one of the world's most isolated places, around 2,000 kilometers off the West African coast. Its environments range from desert-like coasts to tropical forests. It has fostered a biodiversity that is not similar to anything else.

The cloud forest situated around the peak of the island is quite crucial. Its trees get water from the cloud, which drains the island's lower parts and accounts for roughly 60% of the water that falls over the island yearly.

This supports several different plants. These plans include the black-scale fern and the cabbage tree. Notably, the black scale fern hosts at least 120 species of invertebrates that cannot be found elsewhere.

Unfortunately, only a few remnants of the original forest remain. The forest's historic cleanup for crops and cattle and the introduction of invasive species have left just a few fragmented and small patches.

With the support of the Saint Helena National Trust, the UK government, Species Recovery Trust, and RSPB are collaborating to reverse the declines. However, this means that knowing what lives within the cloud forest is more crucial than ever.

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