Genetic techniques have helped uncover a new threatened species of freshwater mussel in southern Western Australia and redefine the range of existing species.

Published in Nature Scientific Reports, a collaboration with researchers from Griffith University, the Western Australian Museum, the University of Western Australia and the University of Nottingham (UK), has formally described a new species of freshwater mussel and two subspecies from southern coastal Western Australia.

Carter’s freshwater mussel (Westralunio carteri) is limited to Australia’s southwest, and was long considered to be the only Westralunio species in Australia, the species is listed as vulnerable on the IUCN Red List and under Australian legislation. 

However the new research confirms the existence of three evolutionary lineages of the Carter’s freshwater mussel, the original Westralunio carteri from western coastal drainages and two significantly smaller and less elongated subspecies: Westralunio inbisi inbisi from southern coastal drainages, and Westralunio inbisi meridiemus from the southwestern corner.

Lead author of the study and research fellow at the Australian Rivers Institute Dr Michael Klunzinger said this is the second study to describe a new species of freshwater mussel in Australia since the 1950s and is the first study in Australia to formally describe a new species of freshwater mussel using both genetic and morphological comparative techniques.

“In order to protect a threatened species, we need to have a scientific name for it to be recognised under Australian state and Commonwealth legislation. More simply, in order to protect a species, we need to give it a name," Dr Klunzinger said.

Following approval from WA Museum's Aboriginal Advisory Committee, the name ‘inbisi’ was selected.

 

Curator of Molluscs at the WA Museum Dr Lisa Kirkendale said 'Inbisi' means freshwater mussel in Nyungar and the research team felt it was important to honour the local indigenous people respecting their long history and knowledge of southwest places, plants and animals including freshwater mussels. 

"The Westralunio inbisi inbisi was found at Goodga River in Two Peoples Bay Nature Reserve, and the Westralunio inibis meridiemus was found at Canebreak Pool in Margaret River. The research team had special permits to collect a small number of specimens at different sites in the State for scientific research purpose," Dr Kirkendale said. 

The southwest coast of Western Australia, where these species inhabit, is affected by climate change and dryland salinity. The clearing of trees for agriculture resulted in a rising groundwater table, dissolving salts stored in the soil, run-off of this salty water into rivers is toxic to freshwater mussels.

Dr Kirkendale said the research demonstrated that Westralunio carteri has a much smaller distributional range than first thought, further emphasising the species' vulnerability. 

"Additional research is underway to address the conservation needs of the species and the newly described subspecies, Westralunio inbisi inbisi and Westralunio inibis meridiemus, given our research findings," Dr Kirkendale said. 

 "A discovery of this nature is crucial to science and the scientists involved. I am proud to have been part of the knowledgeable team involved in this discovery, sharing skills and experience to bring this new species to light." 

*Some of the information and content contained in this article was provided courtesy of Griffith University.