Western Australian Museum scientists describe new species of arachnid from Barrow Island, Western Australia.

MSU's blog | Created 10 months ago

Barrow Island is a Class A nature reserve, located approximately 56 km from the mainland of Western Australia. The island shares a geographical affinity with the Pilbara bioregion, with a recent historical connection to the mainland and Cape Range during lower sea levels approximately 8,000 years ago. Despite this recent connection (at least in evolutionary terms), the island harbours many endemic vertebrate species and subspecies (e.g. Barrow Island Euro, Barrow Island Boodie, Barrow Island Black-and-White Fairy Wren). While the vertebrate fauna on the island is relatively well documented, the invertebrate fauna is still poorly understood. With the recent development of the Gorgon gas processing plant, regular surveys of the biota have uncovered many new invertebrates. Among the newly discovered species on the island are many members of a rarely seen arachnid. Pseudoscorpions, like scorpions, have two pincers they use to grasp food and sense their surroundings. However, unlike scorpions, pseudoscorpions lack the stinging tail and are significantly smaller, with the largest species only reaching 12 millimetres long. Pseudoscorpions are usually found in leaf litter, under rocks, tree bark or in caves. They have even been found in library books, which has led to them sometimes being called ‘book scorpions.’

Specimens of pseudoscorpions from the genus Synsphyronus were discovered across Barrow Island in the mid-2000s. Western Australian Museum researchers Dr Mark Harvey, Dr Kym Abrams and Mieke Burger have confirmed that those specimens belong to a new species, found exclusively on Barrow Island. The species was named Synsphyronus gurdoni, for the Nobel Laureate Sir John Gurdon in recognition of his contributions to developmental biology. The species physically differs from other species in the genus by having highly modified and distinctive pincers.

As well as morphological differences, Western Australian Museum researchers Dr Joel Huey and Mia Hillyer have sequenced the DNA from four specimens of S. gurdoni and compared it to other species of Synsphyronus from across the Pilbara. Using this approach they were able to confirm that, as well as S. gurdoni being genetically distinct from other described species of Synsphyronus, the Pilbara is harbouring many yet-to-be-described species. Many of these putative new species can be explored, including their distributions and evolutionary relationships on the WA Museum’s WAMinals website. Through the Net Conservation Benefits funded project, Conservation Systematics of the Pilbara Fauna, the evolutionary relationships among these species will be published in a forthcoming paper.

While pseudoscorpions have been found on every continent except Antarctica, in all terrestrial environments, Synsphyronus has been especially successful inAustralia, especially in the arid zones. Its most notable feature is the ability to endure extreme heat. In many parts of Australia, Synsphyronus are often found on the undersides of iron rich rocks and boulders, even at the height of summer. This is comparable to other species of the family Garypidae. Indeed, Eremogarypus perfectus from Namibia has the highest heat stupor point – 65°C – recorded for any terrestrial invertebrate. These animals are covered with a lipid layer (epicuticle) which protects them up to temperatures of 56°C.

The description of Synsphyronus gurdoni can be found in the Records of the Western Australian Museum, available online.