Species delineation and systematics of a hemiclonal hybrid complex in Australian freshwaters (Gobiiformes: Gobioidei: Eleotridae: ).

The rivers of southeastern Australia host a species complex within the carp gudgeon genus that includes parental species and hemiclonal hybrid lineages. These hemiclones can be difficult to distinguish from their parent taxa, making delineation of species unusually difficult. We approach this historical taxonomic problem by using single nucleotide polymorphism (SNP) genotyping to distinguish individuals of each species and hemiclones, enabling us to quantify the variation among evolutionary lineages and assign names to the species. remains valid and does not have any hemiclones. We describe and from the Murray-Darling Basin and from the Murray-Darling as well as eastern coastal streams north of the Mary River, part of the range attributed to . We further split to distinguish a species from the Mary River, . We designate a neotype and redescribe due to uncertainty about the source and species identity of specimens used in the original description. We reconcile previous taxonomies, provide new common names for parental species, and advocate using the scientific names of both parents when referring to the hemiclone hybrids to avoid confusion with previous common names that did not distinguish parental taxa and hemiclones.