In biological soil crusts from coastal sites of Ukraine a number of interesting cyanobacterial morphotypes were recorded. Characterization of 7 original strains using molecular, morphological and ecological information revealed that they belong to newly described genera of the orders Pseudanabaenales (Oculatella Zammit, Billi et Albertano et al. and Nodosilinea Perkerson et Casamatta), and Nostocales (Roholtiella M. Bohunická, Pietrasiak et Johansen). In phylogenetic analyses using sequences of the 16S rDNA gene, all Ukrainian strains could be assigned to clades of the corresponding genera with a high degree of support in the Bayesian and Maximum Likelihood analyses. However, their species-level identification has been successful only for one strain of the genus Roholtiella. The phylogeny based on the 16S rRNA gene concatenated with the 16S-23S ITS region of the original strain and 12 published strains of Roholtiella showed that the Ukrainian strain as closely related to R. edaphica Bohunická et Lukešová. Its rRNA secondary structure of the Box B and V3 helices of the 16S-23S ITS region, and nucleotide sequences flanking of them, in main features corresponds to R. edaphica. Original strains of genera Oculatella and Nodosilinea were quite similar to each other by the nucleotide sequences the 16S rDNA gene. At the same time, in phylograms constructed using data from the 16S-23S ITS region of both original and published strains of these genera, they form highly supported clades separated from other species and, thus probably, represent new species. Finding of three new genera for the flora of Ukraine demonstrates the importance of using of modern approaches for the assessment of the real diversity of cyanobacteria in nature.
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