Aspidisca beringiana sp. nov. and Simbiodisca subgen. nov. (Ciliophora, Euplotida), a symbiont of terebellid polychaetes in the Bering Sea

Terebellids in tidal zone of the Bering Island bear three new symbionts - rhabdophryid suctorians, peritrichs with small rosette-like colonies and aspidiscid hypotrich with a long peristome parallel to left body margin. This is the main feature of a new subgenus of the genus Aspidisca, named Simbiodisca. It may deserve the full generic rank if the use of protargol silvering method will not reveal any upper left rudiment of the peristomal membranelles.