Phylogenetic Relationships of the Subclass Peniculia (Oligohymenophorea, Ciliophora) Inferred from Small Subunit rRNA Gene Sequences

Authors

  • MICHAELA C. STRÜDER-KYPKE,

    Corresponding author
    1. Department of Zoology, College of Biological Science, University of Guelph, Guelph, Ontario NIG 2W1, Canada
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  • ANDRÉ-DENIS G. WRIGHT,

    1. Department of Zoology, College of Biological Science, University of Guelph, Guelph, Ontario NIG 2W1, Canada
    2. SIRO Animal Production, Centre for Mediterranean Agricultural Research, Perth, P.O. Wembley, WA 6014, Australia
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  • SERGEI I. FOKIN,

    1. Biological Institute of St. Petersburg State University, Old Peterhof, Oranienbaumskoye sch 2, 198904 St. Petersburg, Russia
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  • DENIS H. LYNN

    1. Department of Zoology, College of Biological Science, University of Guelph, Guelph, Ontario NIG 2W1, Canada
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Corresponding Author: M. Strilder-Kypke—Telephone number: 519– 824–4120 ext. 2975; Fax number: 519–767–1656; Email: mstruede@uoguelph.ca

Abstract

ABSTRACT. Peniculine ciliates have been recognized as a distinct higher taxon of ciliates for almost 50 years. However, phylogenetic relationships within the Subclass Peniculia are still unsettled. To contribute to our understanding of their phylogeny and provide evidence for the position of Urocentrum turbo, we sequenced its small subunit (SS) rRNA gene and the SSrRNA genes from Lemhadion bullinum, Frontonia sp., Paramecium caudatum, Paramecium multimicronucleatum, Paramecium putrinum, and Parameciumwoodruffi. Urocentrum turbo was the only one of these species not to exhibit a shortened Helix E10_1, which we conclude characterizes the “higher” peniculines. Except for U. turbo, the peniculines are strongly supported as a monophyletic clade with Lembadion, Frontonia, and Paramecium species forming separate and strongly supported clades by bootstrap analysis using distance matrix, maximum parsimony, and maximum likelihood methods. Urocentrum turbo is associated with different lineages, depending upon the analysis used. The Paramecium species form at least four clades with the Paramecium aurelia subgroup being the most derived. We conclude that the Subclass Peniculia should be divided into two orders, the Order Urocentrida and Order Peniculida, with the latter order having two suborders, the Suborder Frontoniina and Peniculina. We place U. turbo with the peniculines because of shared morphological and stomatogenetic features.

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