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Coccal cyanobacteria play a very important role in the colonization of aerophytic and subaerophytic habitats, and the genus Chroococcus can be considered one of the most important among them. In view of the polyphyletic character of many traditional genera of cyanobacteria, the genus Chroococcus represents a very complicated group of coccal cyanobacteria and a challenge to current taxonomy. In the territory of the Třesín Natural Monument, we were the first in Europe to discover a population of the related and morphologically very similar cyanobacterium Inacoccus carmineus. By studying morphological variability, the 16S rRNA gene and mass spectra, we refine our knowledge of I. carmineus and its relationship to the genus Chroococcus. Using the MALDI-TOF MS method, we bring another insight into the possibilities of effective classification of cyanobacteria. We believe that, considering the speed, high sensitivity and low cost, this will be a useful method for the classification of cyanobacteria in the future. We reflect on the question of the relationship between morphological and molecular characters and discuss the question of the method of future taxonomic work. [ABSTRACT FROM AUTHOR]

The Nostocales is a monophyletic, heterocytous lineage of cyanobacteria capable of akinete production and division in multiple planes, depending upon family‐level clade. While present in a variety of ecosystems, the diversity of the Nostocales has been poorly elucidated. Due to environmentally ‐induced phenotypic plasticity, morphology alone is often insufficient to determine the true phylogenetic placement of these taxa. In order to bridge this gap, taxonomists now employ the polyphasic approach, combining methods such as morphological analysis, phylogenetic analysis based on DNA sequence and genetic identity based on ribosomal genes, and secondary structure of the 16S‐23S ITS and 16S rRNA gene sequences, as well as ecological characterization. Using this combined approach, a new genus and species (Reptodigitus chapmanii gen. et sp. nov.) isolated from the St. Johns River (Jacksonville, Florida, USA) within the Nostocales is herein described. Phylogenetic analyses place this taxon within the Hapalosiphonaceae, sister to the clade containing Fischerella, Hapalosiphon, and Westiellopsis. The 16S‐23S ITS secondary folding structure analysis also supports the erection of this new genus. [ABSTRACT FROM AUTHOR]

Prokaryotes are the most abundant and diverse inhabitants of the biosphere. However, to directly infer the patterns of their evolutionary history and species diversity requires the study of ancient DNA, which is almost impossible to obtain in free-living prokaryotes. In this paper, we show that cyanobacterial herbarium specimens may serve as a rich source of information to shed light on the genome evolution and species diversity of free-living bacteria. We sequenced two herbarium specimens identified as Nostoc (Cyanobacteria), one of which is over 100 years old. One specimen was identified as N. commune and the second as N. flagelliforme. The two specimens yielded a metagenome composed of six and 11 taxa, respectively. Nostoc was the most abundant in both specimens, with accompanying cyanobacteria and alpha- and beta-proteobacteria. Phylogenomic reconstruction revealed that both Nostoc genomes clustered with a recently sequenced genome of N. flagelliforme CCNUN1. We compared genome properties, including gene composition of N. flagelliforme from the herbarium specimen and N. flagelliforme CCNUN1, both sampled in China. We found a striking difference between the genomes both in gene composition and the presence of genes for secondary metabolites. This poses a potential health risk because N. flagelliforme is consumed in China, and a proper identification of the species strain can be difficult. Furthermore, a surprisingly low frequency of horizontal gene transfer was found within the sequenced Nostoc strains. [ABSTRACT FROM AUTHOR]

Cyanolichens are an assemblage of fungi and cyanobacteria from diverse, cosmopolitan habitats. Typically composed of a single species of cyanobacterium, with or without another eukaryotic alga, here we present two novel cyanobionts isolated from an undescribed tripartite lichen. This endolithic lichen was isolated from a granite cemetery tombstone from Jacksonville, FL, and contains two potentially nitrogen‐fixing cyanobionts. Employing a total evidence approach, we characterized the cyanobionts using molecular (the 16S rDNA and ITS gene region), morphological, and ecological data. Phylogenetic analyses revealed two novel taxa: Brasilonema lichenoides and Chroococcidiopsis lichenoides, both of which fell within well‐supported clades. To our knowledge, this represents the first instance of a tripartite lichen with two cyanobacterial and no eukaryotic members. These types of lichens may well represent an unexplored reservoir of cyanobacterial diversity. The specific epithets are proposed under the provisions of the International Code of Nomenclature for algae, fungi, and plants. [ABSTRACT FROM AUTHOR]

Cyanobacteria represent an ancient, monophyletic lineage of bacteria with the ability to undertake oxygenic photosynthesis. Although they possess a relatively high degree of morphological variability compared with other prokaryotes and there is a wealth of molecular data, there are still significant gaps in our knowledge of cyanobacterial diversity, especially in tropical areas. Here, we present a novel, filamentous, tropical cyanobacterium, which could be classified asPseudophormidiumbased on morphological criteria. A total evidence investigation employing ecological, morphological and genomic data, indicated that our strains form a new and ancient evolutionary lineage among cyanobacteria unrelated toPseudophormidium. Based on this polyphasic assessment, our strains represent a novel, monospecific genus:Elainella. This new genus represents an example of phenotypic convergence, which seems to be a prevalent macroevolutionary pattern in cyanobacteria, a likely cause of the frequently cited polyphyly within a majority of genera. [ABSTRACT FROM AUTHOR]

Two strains of an unusual, filamentous, Geitlerinema-like cyanobacterium inhabiting sandy sediments in Lake Oneida (Jacksonville, Florida) were isolated. These strains possessed a unique combination of specific morphological and molecular characters that enable the establishment of a new monospecific genus on the basis of the type species Jacksonvillea apiculata sp. nov. named in honor of the city of Jacksonville. Morphologically, the species differed from Geitlerinema splendidum and other representatives of the genus Geitlerinema by the presence of spherical structures in the cell walls at cross-walls. Similarly, sequences of the 16S ribosomal RNA gene were below the currently accepted similarity for inclusion into the same genus (i.e. 86% sequence similarity), and were most similar to Desertifilum (88%). To acknowledge the high difference of the Jacksonvillea- Desertifilum clade from members of the family Coleofasciculaceae, we established the new family Desertifilaceae fam. nov., which formed a poorly supported sister clade to some unclear Geitlerinema such the black-band disease strains. [ABSTRACT FROM AUTHOR]