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Phylogeographic study of the West Australian freshwater mussel, Westralunio carteri, uncovers evolutionarily significant units that raise new conservation concerns


South-western Australia is isolated from other forested regions of Australia by desert and bounded on southern and western sides by the Southern and Indian Oceans, respectively, with Westralunio carteri (Iredale, 1934) as the sole endemic freshwater mussel. Its conservation status is vulnerable. This species has a history of nomenclatural change and its systematic placement and population genetic history are largely unknown. We sampled 46 individuals from 13 sites across W. carteri’s distribution and sequenced two mitochondrial genes (16S rDNA and cytochrome c oxidase subunit I) and one nuclear gene (28S rDNA). The mitochondrial haplotype networks and COI phylogenies revealed three evolutionarily significant units (ESUs): “W. carteri” I including the west coast populations, “W. carteri” II from the south and south-eastern range, and “W. carteri” III only occurring in the south-western tip of Australia. Four species delimitation methods identified two molecular operational taxonomic units supporting two distinct species (“W. carteri” I and “W. carteri” II + III). Phylogeographic patterns revealed herein confirm the historical separation of Western and Southern paleo-basins, also highlighting the isolation of the south-western extremity of the region. This underlines the need for taxonomic revision and will require a re-evaluation of W. carteri’s conservation status.

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Genetic analyses were funded by FCT – Portuguese Foundation for Science and Technology COMPETE 2020, Portugal 2020 and the European Union through the ERDF under Project ConBiomics: the missing approach for the Conservation of freshwater Bivalves No NORTE-01-0145-FEDER-030286 and, in part, through a grant from the Holsworth Wildlife Research Endowment. AGS and MLL were also funded by FCT under grants SFRH/BD/137935/2018 and SFRH/BD/115728/2016, respectively. This research was supported by national funds through FCT - Foundation for Science and Technology within the scope of UIDB/04423/2020 and UIDP/04423/2020. Specimen field collection was funded by a Murdoch University PhD Scholarship and a grant from the Holsworth Wildlife Research Endowment. Wildlife collection permits were obtained from the Western Australian Department of Environment and Conservation (SF007049) and the Western Australian Department of Fisheries (1724-2010-06). We thank James Keleher for his assistance during field collection and Corey Whisson and the WA Museum for facilitating specimen collection management. We especially thank the editor and anonymous reviewers for their comments which significantly improved upon earlier versions of this paper.

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Klunzinger, M.W., Lopes-Lima, M., Gomes-dos-Santos, A. et al. Phylogeographic study of the West Australian freshwater mussel, Westralunio carteri, uncovers evolutionarily significant units that raise new conservation concerns. Hydrobiologia (2020).

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  • Unionida
  • Hyriidae
  • Phylogeny
  • Bivalve
  • Species delineation