Invasive and non-invasive lineages inXenostrobus(Bivalvia: Mytilidae)

The mussel genus Xenostrobus comprises eight named extant species from the Indo-West Pacific, including Xenostrobus inconstans, Xenostrobus pulex and Xenostrobus securis from Australia, the latter two also occurring in New Zealand. Xenostrobus species are predominantly restricted to estuaries or sheltered marine habitats although X. pulex inhabits the rocky intertidal on open coasts. Xenostrobus has recently been suggested to be congeneric with the freshwater invasive species Limnoperna fortunei. Xenostrobus securis is itself invasive in the Far East and Europe. This study employed DNA sequences from cytochrome c oxidase (COI), the D1 expansion region of 28S rRNA and the internal transcribed spacers of the ribosomal cistrons to investigate species relationships and habitat transitions in Australasian Xenostrobus. It is unlikely that Xenostrobus and Limnoperna are congeneric as their COI sequences are very different. There was unexpected complexity in defining Xenostrobus species. Xenostrobus pulex from Ne...