EN
The occurrence of eight tetraphyllidean and tetrabothriid cercoids in the alimentary tract of 43 bony fish species (in both adult and larval stages) from three localities, at the South Shetland Islands, South Georgia and the Antarctic convergence line, is reported. Three forms of cercoids with monolocular bothridia (probably Phyllobothrium spp.), as well as a cercoid with undivided bothridia with hook-like projections (probably Dinobothrium sp.), are associated with the pelagic environment. Two forms of cercoids with bilocular bothridia (probably, mainly Pseudanthobothrium spp.), and one form with trilocular bothridia (probably Oncobothrium antarcticum Wojciechowska, 1990), are associated with the benthic zone of fiords and the open sea shelf. Massive infections of predatory fishes with these cercoids were found especially strong in cases of Parachaenichthys spp. (up to 16 thousand cercoids in one host specimen). Cercoids lacking bothridia (probably larval Tetrabothriidae) were found exclusively in a South Georgian fiord. This form is the only one occurring in fish larvae.