Molecular phylogeny of the Helicodontidae and Trissexodontidae (Gastropoda)

Gómez‐Moliner, B.J., Elejalde, A.M., Arrébola, J.R., Puente, A.I., Martínez‐Ortí, A., Ruiz, A. & Madeira, MJ. (2012). Molecular phylogeny of the Helicodontidae and Trissexodontidae (Gastropoda). —Zoologica Scripta, 00, 000–000. In this study, we present a molecular phylogeny of the Trissexodontidae and Helicodontidae obtained by means of Maximum Parsimony, Neighbor Joining, Maximum Likelihood and Bayesian analyses of DNA sequences. Nearly 3 KB of sequence data of two mitochondrial genes (COI, 16S rDNA) and the nuclear rRNA gene cluster including ITS‐1, the 3′end of the 5.8S gene, the complete ITS‐2 region and 5′ end of the large subunit 28S were used to reconstruct the phylogeny of these two families. Monophyly of Trissexodontidae and Helicodontidae at the family level is well supported. A new classification of the genera in the Trissexodontidae is proposed. It includes two subfamilies: Gittenbergeriinae (monotypic for Gittenbergeria turriplana) and Trissexodontinae. The latter includes three strongly supported tribes: (i) Trissexodontini, including Mastigophallus, Trissexodon, Oestophorella and Suboestophora; (ii) Oestophorini, with Oestophora; and (iii) Caracollinini, with Caracollina, Gasulliella, Gasullia and Hatumia. The polytypic Oestophora and Suboestophora are recovered as two monophyletic genera. The anatomy of the auxiliary copulatory organs of the reproductive system is coherent with the new taxonomic interpretation of the Trissexodontidae. Further work, including some more taxa is needed to delimitate subfamilies within Helicodontidae. Finally, the addition of some sequences of other Helicoidea shows that the genus Ciliella is not closely related to Trissexodontidae, being grouped within the Hygromiidae, instead.