Abstract 17 How to cite the abstract: Berger H., Foissner W. (1997): Cladistic relationships of oxytrichid hypotrichs (Protozoa, Ciliophora). - The Journal of Eukaryotic Microbiology, Supplement 44: 30A, Abstract 121. Cladistic Relationships of Oxytrichid Hypotrichs (Protozoa, Ciliophora), HELMUT BERGER and WILHELM FOISSNER Univ. Salzburg, Inst. f. Zoologie, Hellbrunnerstr. 34, 5020 Salzburg, Austria. The relationships of 13 common oxytrichid genera were analysed using Hennig's cladistic method. Twenty-three characters in 4 groups were selected, viz. the morphology of the oral apparatus (3 characters), the infraciliature of the ventral and dorsal side (10 characters), cortical features (2 characters), and ontogenetic particulars (8 characters). All characters and character states are described and discussed using published and original data. Half of the characters originated independently in several genera at least twice, making it very difficult to follow oxytrichid evolution. The autapomorphies of the family Oxytrichidae are 18 characteristically arranged fronto-ventral-transverse cirri and the fragmentation of at least 1 dorsal kinety. The cladogram shows two major branches, termed subfamily Oxytrichinae and subfamily Stylonychinae. 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, Urosomoida and very likely, Australocirrus, Parurosoma and Pseudostrombidium. The Stylonychinae have 3 synapomorphies, viz. the rigid body, an oral apparatus of more than 40% of body length, and the lack of cortical granules. This subfamily comprises Coniculostomum, Histriculus, Steinia, Sterkiella, Stylonychia and, very likely, Parastylonychia and Pleurotricha. Supported by the Austrian FWF (Project PO 8924-Bio) and the Bayerische LAWW. Links Homepage www.protozoology.com Publication list of Helmut Berger Publisher Helmut Berger Main publication to this topic Keywords: review, revision, Ciliophora, Hypotrichia, cladistics, phylogeny, evolution, convergence, morphogenesis, ultrastructure, Coniculostomum, Cyrtohymena, Gonostomum, Histriculus, Notohymena, Onychodromopsis, Oxytricha, Steinia, Sterkiella, Stylonychia, Tachysoma, Urosoma, Urosomoida, Australocirrus, Parastylonychia, Parurosoma, Pleurotricha, Pseudostrombidium, Ancystropodium, Engelmanniella, Gastrostyla, Hemisincirra, Urosoma, Lamtostyla, Laurentiella, Onychodromus, Pattersoniella, Paraurostyla, Terricirra, Territricha, guide, Phylogenie, Stylonychinae, Oxytrichinae, Hypotrichida, Hypotricha, Oligotrichida, Wimpertierchen, electron microscopy, Spirotrichea, ciliates, Ciliate, Ziliaten, Protist, cell division, ontogenesis, Zellteilung Top Dr Helmut BERGER Consulting Engineering Office for Ecology - Technisches Büro für Ökologie Radetzkystrasse 10, 5020 Salzburg, Austria, Europe Phone +43-(0)662-432538; Fax +43-(0)662-443139; email office@protozoology.com; http://www.protozoology.com