Distribution and morphology of two helminths recently introduced into European eel populations: Anguillicola crassus (Nematoda, Dracunculoidea) and Paratenuisentis ambiguus (Acanthocephala, Tenuisentidae)
The occurrence of 2 helminths is reported in eel from 3 regions of the Federal Republic of Germany. Both species, Anguillicola crassus (Nematoda, Dracunculoidea) and Paratenuisentis ambiguus (Acanthocephala, Tenuisentidae) were recently introduced into Europe, probably from Japan and the USA, respectively. The morphology of A. crassus differs from the original description in a few features. Syntype specimens from Japan, however, showed that specimens from Japan and from Germany are conspecific. The morphology of P. ambiguus (first report from Europe) corresponds well with the original description from North America. In Germany it is shown to employ the same crustacean intermediate host as in North America, i.e. Gammarus tigrinus, an amphipod originally introduced purposely into Germany.