Tokophrya sibirica sp. nov. (Ciliophora: Acinetida), a symbiont of freshwater ostracods in Irkutsk Province

Abstract. Freshwater ostracods, even in seasonally drying and freezing ditches, are inhabited by a variety of ciliates, possibly with rapid encysting. Loricates are represented by the genus Lagenophrys, stalked peritrichs, by solitary and colonial species of both Vorticellida and Operculariida; no suctorians have been found so far. The epifauna near St Petersburg and Irkutsk is the same, except for the common occurence of a small tokophryid suctorian on the shell surface of Herpetocypris incongruens along the Angara River and along Listvenka – Irkutsk road; this species may be a regional endemic. A similar but not the same tokophryid inhabits the few examined Baikalian ostracods. This new species, Tokophrya sibirica sp. nov., associated with H. incongruens, is very similar but not identical to T. cyclopum.