SCOLEX MORPHOLOGY OF PROTEOCEPHALUS TAPEWORMS (CESTODA, PROTEOCEPHALIDAE), PARASITES OF FRESH-WATER FISH IN THE PALEARCTIC REGION

The morphology of the scoleces of 11 Proteocephalus species, parasites of freshwater fish in the Palaearctic Region, was compared using ligh t and scanning electron microscopy. The following taxa were evaluated: Proteocephalus ambiguus (Dujardin, 1845); P. cernuae (Gmelin, 1790); P. exiguus La Rue, 1911; P. filicollis (Rudolphi, 1802); P. mucrocepha lus (Creplin, 1825); P. osculatus (Goeze, 1782); P. percae (Muller, 17 80); P. pollanicola Gresson, 1952; P. sagittus (Grimm, 1872); P. thyma lli (Annenkova-Chlopina, 1923); and P. torulosus (Batsch, 1786). Some features as overall shape of the scolex, its size, shape and size of a n apical sucker were found to be fairly stable and species-specific. T he taxa more easily distinguishable from congeners on the basis of the ir scolex morphology were P. cernuae, P. macrocephalus, P. osculatus, P. percae and P. torulosus. The taxonomic importance of the scolex is discussed.