Karyological and karyometric analyses were carried out on freshwater Triclad populations collected in 19 sites of the Coghinas catchment basin (North Sardinia), in order to identify the existing karyotypes and to establish their distribution. By samples collected 25 strains of the gonocephala group and 9 of the lugubris-polychroa group were obtained, on the basis of morphological and reproductive (sexual/fissiparous) caracteristics of the specimens. Within the gonocephala group 177 specimens (168 sexual and 9 fissiparous) were examined and 4 karyotypes
were found as follow: l) diploid karyotype with 2n=2x= 14 belonging to Dugesia hepta species; 2) diploid 2n=2x=16, triploid 2n=3x=24 and aneuploid 2n=?x=32 karyotypes belonging to Dugesia benazzii species. The karyotype with 32 chromosomes, typical of both fissiparous and sexual specimens, is difficult to interpretate owing to the variations in chromosome morphology.
All the karyotypes resulted variously coexisting and distributed.
Within the lugubris-polychroa group 71 specimens were
examined; 2 karyotypes were identified both diploid with
2n=2x=8 respectively belonging to Dugesia mediterranea and Dugesia polychroa species
