Exploring the taxonomy, distribution and evolution of a unique subterranean fauna: amphipod crustaceans from the Yilgarn region of central Western Australia

A project undertaken at the South Australian Museum by Dr Rachael King and Dr Steve Cooper

The stygofauna (those animals that live entirely aquatic lives within groundwater systems) of the Yilgarn region in Western Australia (WA) represent a recently discovered, unique and largely undescribed element of Australian biodiversity. Our aim was to explore, document and revise two important families (Melitidae, Paramelitidae) of crangonyctoid amphipod crustaceans (figure 1), a dominant stygofaunal group, using a combined molecular and morphological approach.

The Yilgarn is a major mining region, rich in mineral deposits such as gold, nickel and uranium. Resource extraction is dependent on large volumes of water drawn from local groundwater systems and has the potential to significantly impact stygofauna. This project provides valuable data towards understanding WA stygobitic amphipod biodiversity and distributions, improves our understanding of subterranean invertebrate evolution and speciation, gives scientific support for informed management of groundwater systems, and facilitates environmental impact assessments.

Our results:

We have explored melitid and paramelitid amphipod diversity across the Yilgarn region of WA with concentrated field collections of fresh material as well as analyses of existing Museum collection material.

We have investigated the evolutionary relationships among the Yilgarn stygobitic Melitidae and Paramelitidae using a combined molecular and morphological approach. Species boundaries have been determined using analyses of molecular lineages and suites of morphological characters as well as biogeographical and hydrogeographical information. Our data documents a rich diversity of melitid and paramelitid genera and species across WA. The melitid amphipods are largely distributed across the Pilbara, Cape Range and Great Sandy Desert region; a new genus with several new species was discovered and the genus Nedsia has been revised with 12 new species. The paramelitid fauna are distributed across the Pilbara and Yilgarn region of WA and our data shows there are 9 new genera and up to 30 new species to be described.

We aim to create bioinformatics tools for the identification of stygobitic amphipods within the Yilgarn: generating interactive web based identification keys with high resolution images.

Figure 1. Stygobitic amphipods (Paramelitidae and Melitidae)