The karyotypes of two Dugesia species from Corfu, Greece (Platyhelminthes, Turbellaria)

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.