Phylogenetic study of the “Megaspiridae” tree snails reveals new families (Gastropoda, Orthalicoidea)

Orthalicoidea is a diverse Gondwanan clade, with over 2,000 species spread mainly throughout the Americas and with small branches living in Australia, New Zealand, and some other South Pacific islands, as well as a relict lineage in southern Africa. The latest phylogenetic study on this superfamily demonstrated that the family Megaspiridae was paraphyletic, with three separate branches, and that the family Orthalicidae remained unresolved as a polytomy. Here we present a new multi-marker molecular phylogenetic study of the Orthalicoidea, with greatly expanded sampling of Orthalicidae and the multiple branches of Megaspiridae, including the unique genus Auris Spix, 1827. Our results have many implications for the classification of the superfamily. Firstly, Megaspiridae is restricted to two genera (Megaspira Lea, 1836 and Callionepion Pilsbry & Vanatta, 1899) and four new families are described: Auriidae fam. nov. Salvador, La Pasta, Silva & Breure; Koridae fam. nov. Salvador, Cavallari & Breure; Orphaicidae fam. nov. Salvador, Rosa, Cavallari & Breure; and Paeniscutalidae fam. nov. Breure & Salvador. Thus, Orthalicoidea now contains 12 families, in a classification scheme that better reflects its diversity. In addition, the family Liguidae, previously considered synonymous with Orthalicidae, is here reestablished as subfamily Liguinae, sister to Orthalicinae. Furthermore, some changes in the taxonomy of genus- and species-level taxa are also proposed.