The phyletic status of the Paludicola

Is the assumption of the monophyly of the Paludicola (freshwater triclads) justified? There seems little doubt on morphological grounds of the close relationship between the Planariidae and the Dendrocoelidae but it is difficult to connect, phylogenetically, the Dugesiidae with these groups. A connection between the former and some of the latter has been unknowingly implied by the author in previous papers, thus raising an anomaly since this would mean that the Dugesiidae are not monophyletic. Is it possible that the Dugesiidae and the Planariidae + Dendrocoelidae have arisen independently from marine ancestors? The implications of such a speculation are examined.