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Australian salt lakes contain a diverse range of endemic invertebrates. The brine shrimp Parartemia is among the most speciose and salt-tolerant of these invertebrates. The morphotaxonomy of Parartemia is well established but there has only been limited molecular assessment of the phylogenetic relationships and boundaries of the morphospecies. We used multiple genetic markers (nuclear 28S and mitochondrial 16S and COI) and tree-building methods (Bayesian inference and maximum likelihood) to investigate the phylogeny of Parartemia. We also used species delimitation methods to test the validity of morphological species designations. The data set included all but 2 of the 18 described Parartemia morphospecies, collected from a total of 93 sites from across southern Australia plus some sequences from GenBank. The results identified large amounts of molecular divergence (e.g. COI P- values of up to 25.23%), some groups of closely related species (which also usually shared some morphological similarities) and some distinctive species, although the relationships among divergent lineages were generally not well resolved. The most conservative set of results from the species delimitation analyses suggests that the morphotaxonomy is largely accurate, although many morphospecies comprised divergent genetic lineages separated by COI P- values of up to 17.02%. Two putative new morphospecies, three cryptic species and one synonymy were identified. Our findings improve the knowledge of Parartemia taxonomy and will facilitate the development of future studies and conservation of this taxon. The brine shrimp Parartemia is a diverse, salt-tolerant genus found in Australian salt lakes. Its current taxonomy is mainly based on morphological data. We used molecular data to investigate the number and relationships of Parartemia species and found two new morphospecies and three cryptic species. Although most species were valid, molecular divergence among and within some species was substantial. Our results confirm the species richness of the genus and our updated species list will aid in targeted conservation efforts. (Image credit: Md Aminul Islam.) [ABSTRACT FROM AUTHOR]

This study uses published and unpublished data to create a comprehensive and up-to-date synthesis of available information on a little-known group of invertebrates, namely, non-marine giant ostracods (cypridids ≥3 mm long). Approximately 8% of the ∼1000 living cypridid species are identified as 'giant'. They occur in a range of subfamilies, in all zoogeographic regions, except Antarctica, and mainly in small standing-water ecosystems. Only those in the subfamily Mytilocypridinae are reasonably well studied. This subfamily is endemic to Australia and comprises a diverse range of giant species (∼29 species in 6 genera), mainly in temporary habitats, mostly salt lakes, including in extreme conditions. We evaluate the current taxonomy of the Mytilocypridinae, analyse patterns in the field distributions and abiotic tolerances of species, and review the general biology of these ostracods. We also identify those species most in need of consideration in conservation planning, highlight critical gaps in knowledge and show how these ostracods could serve as useful models for testing ecological and evolutionary theories. The results of this study can be used to inform conservation planning for giant ostracods and direct further study of these unique invertebrates, which are an important component of the biodiversity of small standing-water ecosystems. It is important that conservation planning considers neglected taxa, supported by scientific studies. Accordingly, we critique the biology of giant ostracods, i.e. ostracods in the family Cyprididae that are ≥3 mm in length. These ostracods are common in small standing-water ecosystems, which are subject to a range of threats. We focus on the subfamily Mytilocypridinae, which consists of a diverse range of giant ostracods that are endemic to Australia and occur mainly in salt lakes, sometimes in extreme conditions. [ABSTRACT FROM AUTHOR]

Westralunio carteri is the only species of freshwater mussel found in south-western Australia and, owing to a lack of comprehensive information on its ecology, its conservation status has been speculative. To more accurately predict the true conservation status of this species, the historical and contemporary distributional records were modelled with environmental data that identified salinity, perenniality and total nitrogen as variables responsible for limiting the species' current extent of occurrence, inferring threatening processes. The species was found to have undergone a 49% reduction in extent of occurrence in less than three generations, due primarily to secondary salinisation. Current distribution is bounded by Gingin Brook in the north to the Kent, Goodga and Waychinicup Rivers in the South, within 50-100 km of coastal south-western Australia. Field observations indicated that W. carteri was almost never found at sites where mean salinity was >1.6 g L-1. This was corroborated by laboratory tolerance trials that showed that W. carteri has an acute salinity tolerance (LD50) of 1.6-3.0 g L-1. Application of IUCN Red List criteria indicates that W. carteri qualifies for listing as vulnerable. Conservation management measures should focus on maintaining existing populations. Freshwater mussels are among the most endangered groups of fauna worldwide. We modelled the distribution of Westralunio carteri and found salinity, perenniality and total nitrogen concentration as the most accurate predictor variables for the species' presence. Salinisation led to a 49% reduction in extent of occurrence, qualifying the species as vulnerable. [ABSTRACT FROM AUTHOR]