Smaller molluscs from a multi-taxon survey (2012–2014) of the shallow marine environments of the tropical Kimberley region, Western Australia

WA Museum Records and Supplements | Updated 4 years ago

ABSTRACT – The marine environments of Western Australia’s Kimberley region (coast to continental edge) are rich in spatial diversity and vast in scale affording a broad range of habitats for marine fauna and flora. The macromolluscan (here defined as adult molluscs >10 mm) diversity of this large marine realm has been the subject of numerous surveys over the last 50 years. However, the smaller molluscs (here defined as adult molluscs <10 mm) have, for the most part, been ignored due to challenges in the collection and study of this assemblage. To begin to redress this imbalance a pilot project specifically designed to target smaller molluscs was undertaken over the final three years (2012–2014) of the survey component of the Woodside Collection Project (Kimberley) 2009–2014. Seventy-seven stations (of 179 surveyed) were sampled yielding 1,883 identified specimen lots representing 505 micromollusc species from ≤5 mm adult size class (following Geiger et al. 2007), 43 species from >5–10 mm adult size class, 68 species from >10 mm adult size class, which are likely to be juveniles of macromolluscs, as well as 8 species whose adult size could not be determined. This diversity spans 102 family or superfamily level taxa. Twenty-one of these familial level taxa were new to the survey area (see Bryce et al. 2018 for a full description of the Kimberley survey area) and the number of taxa recorded from a further 18 families was doubled. A considerable degree of species rarity characterised this fauna with almost 52% of all species being singletons. Less than 22% of taxa were recorded from three or more stations. A total of at least 26 new species, not yet formally described, as well as an additional 23 new records, for the survey area and/or Australia were discovered, yielding 49 new species-level records. Two formal taxonomic revisions are undertaken in this paper due to the acquisition of new material and a review of type material. Firstly, Haplocochlias minutissumus Pilsbry, 1921 is synonymised under Liotina parvissima Hedley, 1899 [as Lophocochlias parvissimus (Hedley, 1899)]. Secondly, the synonymy of Condylocuna io (Bernard, 1915) and Condylocuna tricosa Middelfart, 2002, is revoked. Many putative species require further study to determine their taxonomic status; several are probably new to science.