Dugesia gonocephala (Dugès, 1830) and D. polychroa (Schmidt, 1861), collected from the Greek island of Corfu, have been investigated karyologically. The former is a sexual diploid (2n = 16) in which all the chromosomes are metacentric. The latter is a sexual diploid (2n = 8) with one submetacentric and three metacentric chromosome pairs. Within the Dugesia lugubris-polychroa complex seven biotypes are known. The karyotype of D. polychroa from Corfu is most similar to biotype G from the western Mediterranean. However, there are subtle karyological and morphological differences between the two forms and thus the Corfu population is not assigned to biotype G but is considered to have been derived independently from the basic biotype A. Thus it represents an eighth biotype within the species group.