The tag-along friendship: epibiotic protozoans and syllid polychaetes. Implications for the taxonomy of Syllidae (Annelida), and description of three new species of Rhabdostyla and Cothurnia (Ciliophora, Peritrichia)

The presence of peritrich ciliate epibionts Rhabdostyla sp. and Cothurnia sp. on Syllidae polychaetes is reported here for the first time, including the description of three new species of epibiont ciliates. The protozoans were mainly found at intersegmental furrows, close to parapodial bases of newly collected specimens of Syllis magdalena Wesenberg-Lund, 1962, Syllis sp., Salvatoria sp., and Salvatoria concinna (Westlaeide, 1974) comb. nov. from Chile, Syllis prolifera Krolan, 1852 from Spain, and Prosphaerosyllis magnoculata (Hartmann-Schroder, 1986) from New Zealand. In addition, epibiont protozoans were found on the dorsal surface, nuchal organs, mouth opening, and anterior cirri of Syllis elongata Day, 1949 from Peru, and the ventral surface of Typosyllis macropectinans Hartmann-Schroder, 1982 from Australia. The discovery of protozoan epibionts on syllid polychaetes has important taxonomic implications that are discussed here. The presence of papillae that are in fact misinterpreted ciliate epibionts has been considered a valid character to distinguish among species or to erect new