Mitochondrial DNA (mtDNA) analyses suggest that Southern Hemisphere mussels of the Mytilus edulis species complex include an endemic lineage and invasive genetic elements derived from the Northern Hemisphere species M. galloprovincialis and M. edulis. Haplotypes from these species have been reported in substantial frequencies from South America, South Africa, Western Australia and New Zealand, but only at very low frequencies in Tasmania and the coast near Melbourne in Victoria, the only regions studied in southeastern Australia. Here we investigate cytochrome c oxidase sequences from a wider region in southeastern Australia. Substantial frequencies of Northern Hemisphere Mytilus haplotypes of the female form of the mtDNA were observed, particularly in southern New South Wales. These haplotypes represented a broad range of divergent lineages among the Northern Hemisphere clades. All 3 haplotypes of the male form of mtDNA belonged to the lineage previously identified as the ‘European’ clade of M. edulis.
KEY WORDS: Mytilus · Invasive species · Introgression · Mitochondrial DNA