Molecular phylogenetic investigations of the relationships of the echinoderm-parasite family Eulimidae within Hypsogastropoda (Mollusca)

The gastropod family Eulimidae has attracted considerable attention as one of the most diverse groups of parasitic molluscs in terms of number of species and ranges of body plans and parasitic strategies. However, the phylogenetic position of the family has not been established within the Hypsogastropoda and this has hampered the inference of ancestral states in the evolution of the morphology and parasitic strategies. Here we present Bayesian and maximum likelihood phylograms of Hypsogastropoda based on nuclear and mitochondrial loci (18S and 28S rRNA, Histone H3, COI and 16S rRNA) and a better taxonomic sampling than in previous molecular analyses, to determine the position of Eulimidae. The resulting trees suggest Vanikoridae as the sister group of Eulimidae; the two families are collectively placed in the newly redefined superfamily Vanikoroidea, with Truncatelloidea and (potentially paraphyletic) Rissooidea as closest relatives. Vanikorids are protandrous hermaphrodites as are many eulimids and are essentially carnivorous, differing from the mostly gonochoristic and herbivorous/detritivorous Truncatelloidea and Rissooidea. The mode of feeding may have a phylogenetic signal also within Eulimidae, where radula-less species constitute a robust clade. Other new findings include a close affinity of the submarine-cave Pickworthiidae to Cerithioidea and a terminal position of Nystiellidae within the paraphyletic Epitoniidae.