CLADISTIC RELATIONSHIPS AND GENERIC CHARACTERIZATION OF OXYTRICHID HYPOTRICHS (PROTOZOA, CILIOPHORA)

The relationships of 13 common oxytrichid genera were analysed using c ladistic methods (HENNIG, PAUP). Twenty-three characters in four group s were selected, viz. the morphology of the oral apparatus (three char acters), infraciliature of ventral and dorsal side (ten characters), c ortical features (two characters), and ontogenetic particulars (eight characters). All characters and character states are described and dis cussed using published and original data. Half of the characters origi nated independently in several genera at least twice, making it very d ifficult to follow oxytrichid evolution. The autapomorphies of the fam ily Oxytrichidae are 18 characteristically arranged fronto-ventral-tra nsverse cirri and the fragmentation of at least one dorsal kinety. The cladograms show two major branches, termed subfamily Oxytrichinae JAN KOWSKI and subfamily Stylonychinae n. subfam. The Oxytrichinae have a unique synapomorphy, viz. the participation of cirrus V/3 in primordia formation. This subfamily contains the genera Cyrtohymena, Gonostomum , Notohymena, Onychodromopsis, Oxytricha, Tachysoma, Urosoma, Urosomoi da and, very likely, Australocirrus, Parurosoma and Pseudostrombidium. The Stylonychinae have three synapomorphies, viz. the rigid body, an oral apparatus of more than 40% of body length, and the lack of cortic al granules. This subfamily comprises Coniculostomum, Histriculus, Ste inia, Sterkiella, Stylonychia and, very likely, Parastylonychia and Pl eurotricha. The family Oxytrichidae, its subfamilies, and the genera i ncluded are characterized and keyed. An unambiguous terminology is est ablished for oxytrichid hypotrichs, and synonymy and nomenclature of g enera are discussed.