[The morphological diversity of populations of Proteocephalus percae (Proteocephalidae) in the reservoirs of Karelia].

Morphological parameters of the cestode Proteocephalus percae which is common parasite of a perch were studied in four water bodies of Karelia. Significant morphological variability was observed within populations of the parasite. The phenotypic structure of certain populations of parasite is complicated and differs one population from another.