On Dugesia gonocephala from western Europe

Dugesia gonocephala s.l. is often considered to be a “superspecies” comprising numerous component “microspecies” which are morphologically, karyologically, and reproductively delimited. We have studied populations of D. gonocephala from France, Belgium and The Netherlands and found them to be fairly uniform in respect of most features studied. Nevertheless, discrepancies between them and the “classical” concept of this species as embodied in the literature have raised doubts as to the status and identity of D. gonocephala s. str. A proper understanding of the relationships of the D. gonocephala group can not be obtained without resolution of this problem.