New species of trapdoor spider identified in Mauritius
27 October 2026
A trapdoor spider discovered during conservation work involving Durrell and its Mauritian partners has been formally identified as a species new to science.
The Mauritian Tidal Trapdoor Spider (Idioctis marevallum) lives in the intertidal zone, where its home is completely submerged at high tide or repeatedly hit by waves.
Rather than digging its own burrow, the spider lives in tubes in the coralline bedrock, thought to have been created by worms and molluscs thousands of years ago. It seals the entrance with a trapdoor made from silk, sand and algae, which blends almost perfectly into the surrounding rock.
The spider was first spotted in 2023 on Ilot Vacoas, a tiny one-hectare island off the southeast coast of Mauritius, during conservation work carried out as part of the Mauritius Island Restoration Programme.
The programme is a partnership between Durrell Wildlife Conservation Trust, Mauritian Wildlife Foundation (MWF) and the National Parks and Conservation Service (NPCS), with support from the Forestry Service.
Dr Max Tercel, an entomologist who had recently completed his PhD in collaboration with Cardiff University, Durrell and its Mauritian partners, led the bioblitz team that first found the spider.
“Finding these trapdoor spiders was amazing, it felt like uncovering a hidden treasure. Earlier that day, I had been surveying other habitats on the island, and all that remained was a stretch of coastal rock with sparse vegetation, not somewhere we expected to find something so remarkable.
“It was dark by then, and I was carefully searching through crevices with my headtorch when, to my astonishment, I noticed a familiar pattern: a spider’s legs extending from its burrow, something I’d only ever seen before in lush forests and grasslands.
“I was completely stunned. I called Nik over immediately because I knew we had found something special. It was a privilege to be able to observe these wonderful creatures in their natural habitat.”
Nik Cole, Mauritius Country Manager at Durrell Wildlife Conservation Trust, was part of the team that made the discovery.
“The thing I remember most is Max screaming at me to come over because he’d just seen a mygalomorph - a trapdoor spider. I couldn’t believe something from the same group as tarantulas could be living in a place like this.
I was up all night, holding my phone in the air trying to get a signal and searching for any evidence of a spider like this in Mauritius. At first we thought we might have found Tigidia mauriciana, which was first described in 1892 and had only ever been detected once.
To discover this was actually a new species, after decades of night-time reptile surveys on these islands, was incredibly exciting.”
The spider has now been formally described in a study of the spider fauna of Mauritius by an international team of scientists. The species has been named Idioctis marevallum, with marevallum derived from the Latin for “sea wall”. Following its initial discovery on Ilot Vacoas, it has also been found on Ile aux Fouquets, another small island off southeast Mauritius.
Arachnologist Danniella Sherwood, who led the scientific study formally describing the new species, said:
“It was a great honour and privilege to work with colleagues from Mauritius and in the UK on this material, benefitting from the insights of so many diverse colleagues and organisations.
This paper is an amazing example of what modern scientific collaboration should look like. The fact that one of the newly recorded species was also new to science was the icing on the cake.”
The research brought together experts from the Mauritian Government, Mauritian Wildlife Foundation, Durrell Wildlife Conservation Trust, Natural History Museum London, Cardiff University and Wildlife Preservation Canada.
The wider research also identified a number of spider species not previously recorded in Mauritius, increasing the known spider diversity of the country by more than 25%.
Vikash Tatayah, of the Mauritian Wildlife Foundation, said:
“Despite Mauritius being considered one of the countries having sustained the most significant loss of native biodiversity, it is unbelievable to find amazing species new to science in the most unexpected spots.
This finding supports the urgent need to preserve and restore as many nooks and crannies in the country, since they may still harbour species new to science.”