The paper presents morphological and molecular characterization of the representative of the pantropic genus Brasilonema Fiore et al., first found in the greenhouse in Europe. The genus described in 2007 using an integrated approach is morphologically close to Scytonema Agardh, differing in the filaments forming ascending bundles, rarely occurring false branching and the color of cells. To date, 12 species of Brasilonema have been described; all of them occur subaerophytically in tropical and subtropical regions with a humid climate. For several years in the greenhouse of the N.N. Grishko National Botanical Garden of the NAS of Ukraine, we observed abundant blackish mats with a fleecy surface, formed by falsely branching filaments of heterocytous cyanobacteria, lilac, pale purple or gray in color. Cyanobacteria densely covered the vegetative organs of various tropical epiphytic plants from the Orchidaceae and Bromeliaceae families; sometimes they inhabited concrete and wooden substrates in the greenhouse. The morphological features of the found cyanobacteria were studied both in natural material (samples from the greenhouse) and culture. For cultivation, liquid and agarized N-free BG11 medium was used. The specimens from the mats and the cultures had some differences in thalli habitus, coloration and arrangement of filaments, frequency of false branching, trichome appearance, dimensional limits, etc. A comparative analysis of the original data with descriptions of the known Brasilonema species showed that the Kiev population morphologically and ecologically coincides with several species, of which it is closest to B. octagenarum Aguiar et al. Phylogenetic analysis of the nucleotide sequence of the gene encoding 16S rRNA confirmed affiliation of the original strains to Brasilonema. Analysis of the nucleotide sequence of the 16S-23S ITS region, as well as the secondary structure of its most informative helices, showed the closest proximity of the Kiev material to B. octagenarum, which in turn is probably a complex of species whose taxonomic separation is possible in the future. Presumably, cyanobacteria could get into the Kiev greenhouse with tropical plants brought by Ukrainian botanists from an expedition to Brazil in 1986.
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