[Life cycle of Proteocephalus neglectus (Cestoda) from rainbow trout Salmo gairdneri].

Proteocephalus neglectus is described for the first time in the G.D.R. from Salmo gairdneri. The incidence of invasion was 65% and the main intensity was 2.8 with a maximum of 6 worms per fish. P. neglectus has a 2-host life-cycle. Copepods of the Cyclops strenuus-group and Cyclops furcifer were used as experimental intermediate hosts. The ontogenetic stages oncosphaera (free-living first larva), cercoscolex (second larva in the copepod haemocoel) and preadult (in the gut lumen of the definitive host) were described and compared with other proteocephalid life-cycles. When copepods invaded by oncosphaeres and captured at 14-15 degrees C were eaten by the trouts after 21 days the invasion of the definitive host took place. Parallel tests with Perca fluviatilis were not successful. A transfer of the preadult worms from trout to trout was possible. Some problems of species determination and of terminology were discussed.