Molecular phylogeny of Diplostomum, Tylodelphys, Austrodiplostomum and Paralaria (Digenea: Diplostomidae) necessitates systematic changes and reveals a history of evolutionary host switching events

•Novel sequence data for Diplostomum, Tylodelphys and related genera are provided.•Molecular phylogenies of the group based on 28S and cox1 sequences are presented.•Sequences of 10 previously unidentified larvae are matched with those from adults.•Paralaria alarioides transferred to Diplostomum.•Phylogenetic analysis reveals several host switching events in the history of the group.