Eukaryotic endosymbionts ("parasomes") were studied in Neoparamoeba strains of different origin including two strains of N. pemaquidensis (Page, 1970), the agent of amoebic gill disease (AGD). Comparative study of the endosymbionts revealed their mutual ultrastructural similarity and also similarity with the endosymbiont Perkinsiella amoebae Hollande, 1980 described from Janickina chaetognathi and J.pigmentifera. Morphological features supported Hollande's hypothesis on the kinetoplastid origin of P. amoebae but the first conclusive results were obtained in this study using marker genes. Phylogenetic analyses of SSU rRNA gene sequence data currently available revealed close relationship of the first sequenced Perkinsiella amoebae-like organism with Ichthyobodo necator.
