New subterranean arachnid described from the Pilbara

MSU's blog | Created 2 years ago

The arid zone of Western Australia is a harsh landscape that harbours a surprisingly rich native fauna. To cope with the heat and lack of water, species have adapted in many ways. Perhaps the most extreme method for enduring in this landscape is the colonisation of the subterranean environment. In the caves and interstitial spaces under the surface of the Pilbara, exists a thriving invertebrate fauna, which even includes the enigmatic blind cave eel, Ophisternon sp.

One of the most diverse groups that make up this subterranean fauna is the arachnid order Schizomida. Otherwise known as short-tailed whipscorpions, schizomids superficially appear to be half spider, half cricket, with elongated modified front legs they use as sensory organs. They are named for the short whip-like tail or flagellum that bears important characters for distinguishing species.

Schizomids are common in the tropics, living in rainforests and other moist environments, where their soft bodies can resist desiccation. However, in the Pilbara, they survive by living underground, away from the harsh sun and dry air. It is believed that schizomids (and other denizens of the underground) colonised the subterranean environment more than five million years ago, as the Australian arid zone developed.

From survey work carried out to support decision making for the resources boom in the Pilbara, thousands of specimens of schizomid have been lodged at the Western Australian Museum. Before the description of this newest species, there were four species described from the Pilbara, all belonging to the genus Paradraculoides. From work being carried out by researcher Dr Kym Abrams, and Curator of Arachnology Dr Mark Harvey, it is believed that many dozens of undescribed species from across the region remain undescribed.

From a conservation perspective, schizomids are particularly vulnerable to extinction because species have very small distributions. For example, each of the five previously described species in the Pilbara inhabits a single mesa, with distributions of only a few square kilometres. Many species of schizomid in Western Australia are listed as threatened or vulnerable by the Western Australian Government. The newest member of this group inhabits the Bungaroo iron ore deposit, and is named Paradraculoides eremius for its solitary existence (eremius, Greek, solitude, desert, wilderness).

Much of the taxonomic work on this group has so far been based on a combination of morphological work and DNA sequencing. DNA sequencing work currently being carried out by the Western Australian Museum, funded through the Net Conservation Benefits fund, has found that Paradraculoides eremius is a distinct evolutionary lineage, and that there are many species yet to be described.

Dr Abrams has secured a prestigious Federal grant through the Australian Biological Resources Study and will be describing many of these species from Western Australia over the next three years. This work will also involve nominating species for the WA threatened species list when necessary, securing their long-term survival for future generations.

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