Evolutionary relationships and fine-scale geographic structuring in the temperate percichthyid genus Gadopsis (blackfishes) to support fisheries and conservation management.

Gadopsis (Percichthyidae) is a freshwater genus distributed in south-eastern Australia, including Tasmania, and comprises two recognized species. Previous molecular phylogenetic investigations of the genus, mostly conducted in the pre-genomics era and reflecting a range of geographic and molecular sampling intensities, have supported the recognition of up to seven candidate species. Here we analyze a genome-wide SNP dataset that provides comprehensive geographic and genomic coverage of Gadopsis to produce a robust hypothesis of species boundaries and evolutionary relationships.

Cryptic diversity within two widespread diadromous freshwater fishes (Teleostei: Galaxiidae).

Identification of taxonomically cryptic species is essential for the effective conservation of biodiversity. Freshwater-limited organisms tend to be genetically isolated by drainage boundaries, and thus may be expected to show substantial cryptic phylogenetic and taxonomic diversity. By comparison, populations of diadromous taxa, that migrate between freshwater and marine environments, are expected to show less genetic differentiation.

Cherax latimanus sp. nov., a new burrow-dwelling freshwater crayfish (Decapoda, Parastacidae) from the mid-Murray River catchment, Australia.

A new species of freshwater crayfish in the southern hemisphere family Parastacidae is described from the Murray Darling Basin (MDB), eastern Australia. The Swamp Yabby, Cherax latimanus sp. nov.

Revision of the genus Hannia (Teleostei, Terapontidae), with description of a new species, Hannia wintoni, from the Kimberley, Western Australia.

The systematics of the genus Hannia Vari 1978, endemic to freshwater habitats of remote north-western Australia, is revised in light of recent collections in the region and a molecular study of the group that identified an undescribed candidate species. A new freshwater fish species (Hannia wintoni sp. nov) is described based on analysis of multiple nuclear genetic markers (53 allozyme loci), mitochondrial DNA sequence data (601 bp cytochrome b) and morphology (examination of a suite of 66 morphometric and meristic characters).

Multispecies models reveal that eDNA metabarcoding is more sensitive than backpack electrofishing for conducting fish surveys in freshwater streams.

Environmental DNA (eDNA) sampling can provide accurate, cost-effective, landscape-level data on species distributions. Previous studies have compared the sensitivity of eDNA sampling to traditional sampling methods for single species, but similar comparative studies on multispecies eDNA metabarcoding are rare. Using hierarchical site occupancy detection models, we examined whether key choices associated with eDNA metabarcoding (primer selection, low-abundance read filtering and the number of positive water samples used to classify a species as present at a site) affect the sensitivity of metabarcoding, relative to backpack electrofishing for fish in freshwater streams.

Revision of the Australian Wet Tropics endemic rainbowfish genus Cairnsichthys (Atheriniformes: Melanotaeniidae), with description of a new species.

The freshwater melanotaeniid genus Cairnsichthys is endemic to a relatively small area of specialised habitat within the Wet Tropics bioregion of north-eastern Queensland, Australia. It was previously considered as monotypic, including only a single species, C. rhombosomoides (Nichols Raven, 1928).

Genome-wide SNPs resolve a key conflict between sequence and allozyme data to confirm another threatened candidate species of river blackfishes (Teleostei: Percichthyidae: Gadopsis).

Conflicting results from different molecular datasets have long confounded our ability to characterise species boundaries. Here we use genome-wide SNP data and an expanded allozyme dataset to resolve conflicting systematic hypotheses on an enigmatic group of fishes (Gadopsis, river blackfishes, Percichthyidae) restricted to southeastern Australia. Previous work based on three sets of molecular markers: mtDNA, nuclear intron DNA and 51 allozyme loci was unable to clearly resolve the status of a putative fifth candidate species (SWV) within Gadopsis marmoratus.

A review of Galaxiella pusilla (Mack) (Teleostei: Galaxiidae) in south-eastern Australia with a description of a new species.

The dwarf galaxias, Galaxiella pusilla (Mack), is a small, threatened freshwater fish from coastal south-eastern Australia. Recent genetic studies, using multiple nuclear and mitochondrial DNA markers, found substantial differences between populations in western Victoria and south Australia ('west region') compared to eastern Victoria, Flinders Island, and Tasmania ('east region') that suggest the presence of a cryptic species. Morphological measurements and meristic counts from multiple populations within each region were undertaken to investigate potential differences between regions.

Fifteen from one: a revision of the Galaxias olidus Günther, 1866 complex (Teleostei, Galaxiidae) in south-eastern Australia recognises three previously described taxa and describes 12 new species.

The systematics of the Galaxias olidus hyper-species complex from freshwater habitats in south-eastern, mainland Australia is revised. Galaxias olidus Günther 1866 is redescribed, Galaxias fuscus Mack 1936 and Galaxias ornatus Castelnau 1873, previously synonymised with G. olidus (sensu lato), are reinstated as valid taxa and redescribed, and 12 taxa are described as new: Galaxias aequipinnis sp.

Global biodiversity assessment and hyper-cryptic species complexes: more than one species of elephant in the room?

Several recent estimates of global biodiversity have concluded that the total number of species on Earth lies near the lower end of the wide range touted in previous decades. However, none of these recent estimates formally explore the real "elephant in the room", namely, what proportion of species are taxonomically invisible to conventional assessments, and thus, as undiagnosed cryptic species, remain uncountable until revealed by multi-gene molecular assessments. Here we explore the significance and extent of so-called "hyper-cryptic" species complexes, using the Australian freshwater fish Galaxias olidus as a proxy for any organism whose taxonomy ought to be largely finalized when compared to those in little-studied or morphologically undifferentiated groups.