Phylogeny of the Aplysiidae (Gastropoda, Opisthobranchia) with new aspects of the evolution of seahares

The phylogeny of the Aplysiidae is investigated, based on 37 morphological and histological characters polarized a priori by outgroup comparison. The Aplysiidae represents a monophyletic taxon comprising two distinct clades: Aplysiinae and Dolabellinae + Dolabriferinae + Notarchinae. The traditional classification of Longicommissurata (Aplysiinae + Dolabellinae) is no longer valid since the Longicommissurata are paraphyletic. However, the Brevicommissurata (Dolabriferinae + Notarchinae) form a monophyletic group. Within the Dolabriferinae two sister-groups can be distinguished: Dolabrifera and Phyllaplysia + Petalifera petalifera . The genus Petalifera is paraphyletic. Based on the present phylogeny, several aspects of the evolution of the Aplysiidae are discussed.