title: Molecular and morphological criteria for revision of the genus Microcoleus (Oscillatoriales, Cyanobacteria).
abstract: Ninety-two strains of Microcoleus vaginatus (=nomenclatural-type species of the genus Microcoleus Desmazières ex Gomont) and Phormidium autumnale Trevisan ex Gomont from a wide diversity of regions and biotopes were examined using a combination of morphological and molecular methods. Phylogenies based on the 16S rDNA and 16S-23S ITS (partial) demonstrated that the 92 strains, together with a number of strains in GenBank, were members of a highly supported monophyletic clade of strains (Bayesian posterior probability = 1.0) distant from the species-cluster containing the generitype of Phormidium. Similarity of the 16S rRNA gene exceeded 95.5% among all members of the Microcoleus clade, but was less than 95% between any Microcoleus strains and species outside of the clade (e.g., Phormidium sensu stricto). These findings, which are in agreement with earlier studies on these taxa, necessitate the revision of Microcoleus to include P. autumnale. Furthermore, the cluster of Phormidium species in the P. autumnale group (known as Group VII) must be moved into Microcoleus as well, and these nomenclatural transfers are included in this study. The main diacritical characters defining Microcoleus are related to the cytomorphology of trichomes, including: narrowed trichome ends, calyptra, cells shorter than wide up to more or less isodiametric, and facultative presence of sheaths. The majority of species are 4-10 μm in diameter. The possession of multiple trichomes in a common sheath is present facultatively in many but not all species.
authors.affiliation: Institute of Botany, Centre for Phycology, The Academy of Sciences of the Czech Republic, Dukelská 135, Třeboň, 379 82, Czech Republic.|Centre for Polar Ecology, Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branisovska 31, Ceske Budejovice, 370 05, Czech Republic.
authors.forename: Otakar
authors.initials: O
authors.lastname: Strunecký
authors.affiliation: Institute of Botany, Centre for Phycology, The Academy of Sciences of the Czech Republic, Dukelská 135, Třeboň, 379 82, Czech Republic.|Institute of Botany, Faculty of Science, University of South Bohemia, Branisovska 31, Ceske Budejovice, 370 05, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Komárek
authors.affiliation: Biology, John Carroll University, University Heights, Ohio, 44118, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Johansen
authors.affiliation: Institute of Soil Biology, Biology Centre ASCR, v.v.i., Na Sádkách 7, České Budějovice, 370 05, Czech Republic.
authors.forename: Alena
authors.initials: A
authors.lastname: Lukešová
authors.affiliation: Institute of Botany, Centre for Phycology, The Academy of Sciences of the Czech Republic, Dukelská 135, Třeboň, 379 82, Czech Republic.|Centre for Polar Ecology, Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branisovska 31, Ceske Budejovice, 370 05, Czech Republic.
authors.forename: Josef
authors.initials: J
authors.lastname: Elster
keywords: Cyanobacteria; Microcoleus; Phormidium; molecular evaluation; morphology; phylogeny; taxonomy