WATCH: Durrell helps to uncover new species of trapdoor spider

Durrell has helped to uncover a new species of spider in Mauritius!

The Mauritian Tidal Trapdoor Spider lives in wave-battered coastal rocks and is completely submerged at high tide, sealing its burrow with a camouflaged trapdoor made from silk, sand, and algae.

The spider was first spotted in 2023 on Ilot Vacoas, a tiny one-hectare island off the southeast coast of Mauritius, as part of the Mauritius Island Restoration Programme.

That 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 led the bioblitz team that first found the spider, said:

"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, and part of the team who made the discovery, said:

"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 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 wider research also identified many spider species not previously recorded in Mauritius, increasing the known spider diversity there 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."