A phylogenetic analysis of rissooidean and cingulopsoidean families (Gastropoda: Caenogastropoda).

The Rissooidea is one of the largest and most diverse molluscan superfamilies, with 23 recognized Recent families including marine, freshwater and terrestrial members. The Cingulopsoidea are a group of three marine families previously included within the Rissooidea. A previous molecular analysis including two rissooideans and one cingulopsoidean, indicated the possibility that the Rissooidea is at least diphyletic. We use new molecular data to investigate the polyphyly of Rissooidea and test the monophyly of Cingulopsoidea with a greatly increased taxon set. This study includes the greatest sampling to date with 43 species of 14 families of Rissooidea and all families of Cingulopsoidea. Bayesian and maximum likelihood analyses of 16S and 28S show that there are two major clades encompassing taxa previously included in Rissooidea. These are the Rissooidea s.s. containing Rissoidae and Barleeiidae and the Truncatelloidea containing Anabathridae, Assimineidae, Falsicingulidae, Truncatellidae, Pomatiopsidae, Hydrobiidae s.l., Hydrococcidae, Stenothyridae, Calopiidae, Clenchiellidae, Caecidae, Tornidae, and Iravadiidae. Rissoidae is not monophyletic, with Lironoba grouping with Emblanda (Emblandidae) and Rissoina forming a separate clade with Barleeiidae. Iravadiidae is not monophyletic, with Nozeba being sister to the Tornidae. Tatea, usually included within Hydrobiidae, is distinct from that family and Nodulus, previously included in Anabathridae, groups with the hydrobiids.