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Molecular Phylogeny of the Heterotrichea (Ciliophora, Postciliodesmatophora) Based on Small Subunit rRNA Gene Sequences


Corresponding Author: S. Schmidt, Department of Molecular Evolution and Animal Systematics, University of Leipzig, Talstraße 33, Leipzig 04103, Germany—Telephone number: +49 341 9736718; FAX number: +49 341 9736789; e-mail:


ABSTRACT. A comprehensive molecular analysis of the phylogenetic relationships within the Heterotrichea including all described families is still lacking. For this reason, the complete nuclear small subunit (SSU) rDNA was sequenced from further representatives of the Blepharismidae and the Stentoridae. In addition, the SSU rDNA of a new, undescribed species of the genus Condylostomides (Condylostomatidae) was sequenced. The detailed phylogenetic analyses revealed a consistent branching pattern: while the terminal branches are generally well resolved, the basal relationships remain unsolved. Moreover, the data allow some conclusions about the macronuclear evolution within the genera Blepharisma, Stentor, and Spirostomum suggesting that a single, compact macronucleus represents the ancestral state.