A hydrothermal vent mite (Halacaridae, Acari) with a new Corynophrya species (Suctoria, Ciliophora), description of the suctorian and its distribution on the halacarid mite.

Copidognathus nautilei Bartsch, 1997, from a hydrothermal vent field of the Mid-Atlantic Ridge at about 13 degrees N, 45 degrees W and 4090 m depth, was infested with the suctorian Corynophrya abyssalis n. sp., with up to 58 epizoans per mite. The new suctorian has a sacciform body with seven longitudinal ribs, a compact macronucleus and up to 40 non-retractile tentacles. The budding is exogenous. The systematic position of the new species and the genus Corynophrya is discussed, as well as infestation rates and sites of suctorians on their halacarid hosts.