Contributions to Zoology, 85 (1) – 2016Dick S.J. Groenenberg; Peter Subai; Edmund Gittenberger: Systematics of Ariantinae (Gastropoda, Pulmonata, Helicidae), a new approach to an old problem
Material and methods

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Systematics

Genera and subgenera are taxonomic ranks. To make the ranking less subjective, a cladistic approach is required. Throughout this study, clades that are sister-groups of one another do not differ in their taxonomic ranking. This leaves the option open to give the same ranking also to clades that do not have a sister-group relationship. As a consequence, a genus may have more than two subgenera. Since there are many more splitting points in evolutionary history than taxonomic ranks, this cannot be avoided. Genera are always based on monophyletic species groups. In some cases, at the subgeneric level, paraphyletic taxa are accepted. Genetic distances were not used as decisive in deciding upon the status of genus versus subgenus.

When morphologically cryptic taxa are unequivocally brought to light by the molecular analyses, these taxa are not neglected but formally characterized and named, as advocated by Cook et al. (2010), Gittenberger and Gittenberger (2011) and Jörger and Schrödl (2013). Abbreviations: PP = posterior probability, MYA = million years ago.