Guest blog by Danni Sherwood, Research Associate, Arachnology Research Association, and Liza Fowler, Cloud Forest Invertebrate Specialist, Saint Helena National Trust, both IUCN SSC Mid-Atlantic Islands Invertebrate Specialist Group members.
Saint Helena, a UK Overseas Territory deep in the South Atlantic Ocean, is the most important site for wildlife on British soil. Its remote location (it lies 2,000km off the coast of West Africa) meant that the wildlife that reached the island quickly diversified, evolving into hundreds of species that exist nowhere else on earth.
Its isolation also makes it difficult for scientists to access. But funding through the St Helena Cloud Forest Project meant that Danni was able to travel and work with Liza and other colleagues on island to solve decade-long mysteries.
The result – they found three new species of spider! Along with a whole wealth of unexpected new discoveries for the greater body of knowledge on spiders in the South Atlantic Ocean.
The history of spider research on Saint Helena
The spiders of Saint Helena were first studied in 1870 by the famous arachnologist Octavius Pickard-Cambridge, who studied spiders collected in 1869 by Saint Helenian surveyor and military officer John Charles Melliss. Nearly a hundred years later, an expedition by the Royal Museum for Central Africa brought new specimens to light, which were mostly published on by scientists in 1977.
Our research
After this period, virtually nothing was published on the taxonomy (scientific classification) of spiders until 2022. Recent research, led by Danni in the UK with on-island support from Liza, involved many different approaches and methodologies. Danni’s research on existing spider specimens in museums, including the original specimens collected by Melliss, took her to research institutions in Oxford, London, Belgium and Germany.
The examination of more recent material, collected by Prof. Philip Ashmole and his wife Myrtle, provided a modern insight into the spider populations of Saint Helena.
Finally, a funded one-month expedition to the island for Danni was organised, to focus on investigating spider ecology in the precious cloud forest, led by Liza, and to enable Danni to train Saint Helena National Trust and Saint Helena Government staff on how to use an improved user-friendly spider key to recognise the island’s eight-legged inhabitants. It also gave an opportunity to conducted further fieldwork all over the island.
Through this, they were able to discover that some of the old species were not different from each other. When this happens, the one that was described first gets priority and the other becomes a “synonym” and is not used anymore. Excitingly, they also found several new species that were totally new to science.
New species discovered recently
The first of these new species is the Mt Vesey Waterfall Wolf Spider (Hogna veseyensis), a remarkable species which is only known to live under water-logged rocks and the rock face of the Mt Vesey Waterfall, within the Peaks National Park. It probably has one of the smallest known ranges of any invertebrate in the world.
A female of the Mt. Vesey Wolf Spider (Hogna veseyensis) (c) Liza Fowler
The second new species is the Mole Spider (Molearachne sanctaehelenae). This spider is also a wolf spider, but unlike almost all other species, it makes many underground tunnels and mounds on the ground of its semi-desert home and has one pair of eyes very small (usually these are larger than the other eyes). These special features made it iconic in Saint Helena, even before it was known to be its own species. It lives on Prosperous Bay Plain, including in and around the airport, and may also occur at another spot called Blue Point but this requires further examination of specimens. It could be that the Blue Point spiders are a closely related but distinct species.
A male of the Mole Spider (Molearachne sanctaehelenae) (c) Prof. Philip Ashmole
The third new species is the Daryl Wolf Spider (Dolocosa joshuai), which occurs only on Horse Point and Prosperous Bay Plain, the arid parts of the island. This new species was named after Daryl Joshua, a young conservationist working for the Saint Helena National Trust, who took a great interest in spiders. Whilst on the island, Danni mentored Daryl, showing him how to identify and scientifically document the island’s spiders. We hope he will one day become Saint Helena’s own spider expert!
A female of Daryl Wolf Spider (Dolocosa joshuai) (c) Prof. Philip Ashmole
There may still be new species to come as we continue to study the spiders of the island. Our work also made other important discoveries, such as the Peaks Woodlouse Spider (Tecution planum) – which has massive jaws that might help it eat woodlice and beetles despite their chitin armour – previously thought to be three species, but we found it is instead of just one. By knowing it is only one species and found only in the cloud forest, we can understand it is a threatened species and hopefully encourage it to be conserved for the future.
A male of the Peaks Woodlouse Spider (Tecution planum), photo by Liza Fowler
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