title: POLYPHYLY OF CHAETOPHORA AND STIGEOCLONIUM WITHIN THE CHAETOPHORALES (CHLOROPHYCEAE), REVEALED BY SEQUENCE COMPARISONS OF NUCLEAR-ENCODED SSU rRNA GENES(1).
abstract: Previously published molecular phylogenetic analyses of the Chaetophorales (Chlorophyceae) suffered from limited taxon sampling (six genera with only a single species per genus). To test the monophyly of species-rich genera, and to analyze the phylogenetic relationships among families and genera in the Chaetophorales, we determined nuclear-encoded SSU rDNA sequences from 30 strains of Chaetophorales, performed phylogenetic analyses using various methods, and screened clades for support by unique molecular synapomorphies in the SSU rRNA secondary structure. The Schizomeridaceae and the weakly supported Aphanochaetaceae were recovered as basal lineages. The derived family Chaetophoraceae diverged into two clades: the "Uronema clade" containing unbranched filaments, and a sister clade designated as "branched Chaetophoraceae" comprising Chaetophora, Stigeoclonium, Draparnaldia, Caespitella, and Fritschiella. Although some terminal clades corresponded to genera described (e.g., Caespitella and Draparnaldia), other clades were in conflict with traditional taxonomic designations. Especially, the genera Stigeoclonium and Chaetophora were shown to be polyphyletic. The globose species Chaetophora elegans was unrelated to lobate Chaetophora spp. (e.g., Chaetophora lobata). Since the original description of Chaetophora referred to a lobate thallus organization, the latter clade represented Chaetophora sensu stricto. In consequence, C. lobata was designated as lectotype of Chaetophora. Two Stigeoclonium species, Stigeoclonium farctum Berthold and Stigeoclonium'Longipilus', diverged independently from the type species of Stigeoclonium, Stigeoclonium tenue (C. Agardh) Kütz. These results indicated that some commonly used taxonomic characters are either homoplasious or plesiomorphic and call for a reevaluation of the systematics of the Chaetophorales using novel morphological and molecular approaches.
authors.affiliation: Institute of Botany v.v.i., Academy of Sciences of the Czech Republic, Dukelská 135, CZ - 379 82 Třeboň, Czech Republic Faculty of Science, University of South Bohemia, Branišovská 31, CZ - 370 05 České Budějovice, Czech RepublicBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, GermanyDepartment Limnology, University of Vienna, Althanstr. 14, A-1090 Vienna, AustriaBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, Germany.
authors.forename: Lenka
authors.initials: L
authors.lastname: Caisová
authors.affiliation: Institute of Botany v.v.i., Academy of Sciences of the Czech Republic, Dukelská 135, CZ - 379 82 Třeboň, Czech Republic Faculty of Science, University of South Bohemia, Branišovská 31, CZ - 370 05 České Budějovice, Czech RepublicBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, GermanyDepartment Limnology, University of Vienna, Althanstr. 14, A-1090 Vienna, AustriaBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, Germany.
authors.forename: Birger
authors.initials: B
authors.lastname: Marin
authors.affiliation: Institute of Botany v.v.i., Academy of Sciences of the Czech Republic, Dukelská 135, CZ - 379 82 Třeboň, Czech Republic Faculty of Science, University of South Bohemia, Branišovská 31, CZ - 370 05 České Budějovice, Czech RepublicBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, GermanyDepartment Limnology, University of Vienna, Althanstr. 14, A-1090 Vienna, AustriaBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Sausen
authors.affiliation: Institute of Botany v.v.i., Academy of Sciences of the Czech Republic, Dukelská 135, CZ - 379 82 Třeboň, Czech Republic Faculty of Science, University of South Bohemia, Branišovská 31, CZ - 370 05 České Budějovice, Czech RepublicBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, GermanyDepartment Limnology, University of Vienna, Althanstr. 14, A-1090 Vienna, AustriaBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Pröschold
authors.affiliation: Institute of Botany v.v.i., Academy of Sciences of the Czech Republic, Dukelská 135, CZ - 379 82 Třeboň, Czech Republic Faculty of Science, University of South Bohemia, Branišovská 31, CZ - 370 05 České Budějovice, Czech RepublicBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, GermanyDepartment Limnology, University of Vienna, Althanstr. 14, A-1090 Vienna, AustriaBiozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Melkonian
keywords: 18S rDNA; Aphanochaete; Caespitella; Chaetophora; Chaetophorales; Draparnaldia; Fritschiella; Stigeoclonium; phylogeny; polyphyly