Molecular phylogeny of Australian Helicarionidae, Euconulidae and related groups (Gastropoda: Pulmonata: Stylommatophora) based on mitochondrial DNA.

The delineation and phylogenetic relationships of the pulmonate family Helicarionidae are currently poorly understood. We have undertaken a phylogenetic analysis of Australian members of Helicarionidae. Three consecutive mitochondrial genes (COI, tRNA-val and 16S rRNA) were sequenced for 36 species from Helicarionidae and related groups. Helicarionidae grouped with Ariophantidae and Urocyclidae with good support in all trees, as did Microcystinae with Trochomorphidae, corresponding to the results of a previous morphological study, but the relationships of Euconulinae and Limacidae could not be resolved. Cystopeltidae never grouped with Helicarionidae and should be regarded as a separate family. The position of tRNA-val in the mitochondrial genome provided a new synapomorphy for Microcystinae. In addition, the COI and 16S rRNA sequences showed a high degree of compositional heterogeneity and incompatibility of phylogenetic signals, highlighting the importance of testing for the decay of the historical signal prior to the phylogenetic analysis.