Heleobia maltzani (Westerlund, 1886) (Caenogastropoda: Truncatelloidea: Cochliopidae) from Crete and species-level diversity of Heleobia Stimpson, 1865 in Europe

Morphological characters and partial cytochrome oxidase (COI) DNA sequences were used to investigate intra- and interpopulation differences among three Cretan brackish-water populations of Heleobia maltzani snails. The morphology of male and female reproductive organs of H. maltzani did not differ within studied populations or in comparison with closely related species. In contrast, analysis of shell morphology revealed substantial variation not supported by the genetic data. Genetics results showed surprisingly low differentiation between all Cretan populations and also mainland populations of Heleobia. They also showed that H. maltzani is conspecific with four other European species of Heleobia, thus implying that there is only one species of brackish-water Heleobia in Europe. Such a low level of genotypic differentiation is unusual for typical island species and is most probably the consequence of recent colonization of Crete. Possible scenarios of such processes are discussed.