Amazonocrinis nigriterrae gen. nov., sp. nov., Atlanticothrix silvestris gen. nov., sp. nov. and Dendronalium phyllosphericum gen. nov., sp. nov., nostocacean cyanobacteria from Brazilian environments.

The cyanobacterial genus Nostoc is an important contributor to carbon and nitrogen bioavailability in terrestrial ecosystems and a frequent partner in symbiotic relationships with non-diazotrophic organisms. However, since this currently is a polyphyletic genus, the diversity of Nostoc-like cyanobacteria is considerably underestimated at this moment. While reviewing the phylogenetic placement of previously isolated Nostoc-like cyanobacteria originating from Brazilian Amazon, Caatinga and Atlantic forest samples, we detected 17 strains isolated from soil, freshwater, rock and tree surfaces presenting patterns that diverged significantly from related strains when ecological, morphological, molecular and genomic traits were also considered. These observations led to the identification of the evaluated strains as representative of three novel nostocacean genera and species: Amazonocrinis nigriterrae gen. nov., sp. nov.; Atlanticothrix silvestris gen. nov., sp. nov.; and Dendronalium phyllosphericum gen. nov., sp. nov., which are herein described according to the rules of the International Code of Nomenclature for algae, fungi and plants. This finding highlights the great importance of tropical and equatorial South American ecosystems for harbouring an unknown microbial diversity in the face of the anthropogenic threats with which they increasingly struggle.

The Compositionally Distinct Cyanobacterial Biocrusts From Brazilian Savanna and Their Environmental Drivers of Community Diversity.

The last decade was marked by efforts to define and identify the main cyanobacterial players in biological crusts around the world. However, not much is known about biocrusts in Brazil's tropical savanna (cerrado), despite the existence of environments favorable to their development and ecological relevance. We examined the community composition of cyanobacteria in biocrusts from six sites distributed in the Southeast of the country using high throughput sequencing of 16S rRNA and phylogenetic placement in the wider context of biocrusts from deserts. Sequences ascribable to 22 genera of cyanobacteria were identified. Although a significant proportion of sequences did not match those of known cyanobacteria, several clades of Leptolyngbya and Porphyrosiphon were found to be the most abundant. We identified significant differences in dominance and overall composition among the cerrado sites, much larger than within-site variability. The composition of cerrado cyanobacterial communities was distinct from those known in biocrusts from North American deserts. Among several environmental drivers considered, the opposing trend of annual precipitation and mean annual temperature best explained the variability in community composition within Brazilian biocrusts. Their compositional uniqueness speaks of the need for dedicated efforts to study the ecophysiology of tropical savanna biocrust and their roles in ecosystem function for management and preservation.

Polyphasic approach using multilocus analyses supports the establishment of the new aerophytic cyanobacterial genus Pycnacronema (Coleofasciculaceae, Oscillatoriales).

A new Phormidium-like genus was found during an investigation of Oscillatoriales diversity in Brazil. Eight aerophytic populations from south and southeastern regions were isolated in monospecific cultures and submitted to polyphasic evaluation. The populations presented homogeneous morphology with straight trichomes, not attenuated, and apical cell with thickened cell wall. Phylogenetic analyses based on 16S rRNA gene sequences showed that these populations, plus the Brazilian strain Phomidium sp. B-Tom from GenBank, formed a highly supported and distinctive clade, which corresponds to the new genus Pycnacronema, comprising six new species: P. brasiliensis (type species), P. arboriculum, P. conicum, P. marmoreum, P. rubrum, and P. savannensis. These results were confirmed and supported by rpoC1 and rbcL genes evaluated independently and by the concatenated analysis of 16S rRNA, rpoC1 and rbcL genes (for all species but P. savannensis). Secondary structures of the D1-D1', box-B, and V3 regions of the internal transcribed spacer were informative at specific level, being conserved in P. brasiliensis and variable among the other strains, also confirming the phylogenetic analyses. The generic name and specific epithets of the new taxa are proposed under the provisions of the International Code of Nomenclature of algae, fungi, and plants.

Kryptousia macronema gen. nov., sp. nov. and Kryptousia microlepis sp. nov., nostocalean cyanobacteria isolated from phyllospheres.

Tropical ecosystems worldwide host very diverse microbial communities, but are increasingly threatened by deforestation and climate change. Thus, characterization of biodiversity in these environments, and especially of microbial communities that show unique adaptations to their habitats, is a very urgent matter. Information about representatives of the phylum Cyanobacteria in tropical environments is scarce, even though they are fundamental primary producers that help other microbes to thrive in nutrient-depleted habitats, including phyllospheres. In order to increase our knowledge of cyanobacterial diversity, a study was conducted to characterize isolates from Avicennia schaueriana and Merostachys neesii leaves collected at a mangrove and an Atlantic forest reserve located at the littoral of São Paulo state, south-east Brazil. The morphological, ultrastructural, phylogenetic, molecular and ecological features of the strains led to the recognition of the new genus Kryptousia, comprising two new species, Kryptousiamacronema gen. nov., sp. nov. and Kryptousiamicrolepis sp. nov., described here according to the International Code of Nomenclature for algae, fungi and plants. The new genus and species were classified in the nostocalean family Tolypotrichaceae. This finding advances knowledge on the microbial diversity of South American ecosystems and sheds further light on the systematics of cyanobacteria.

Potamolinea gen. nov. (Oscillatoriales, Cyanobacteria): a phylogenetically and ecologically coherent cyanobacterial genus.

Phormidium Kützing ex Gomont, a common genus of the Cyanobacteria, is widely known as a problematic group. Its simple morphology is not congruent with its genetic heterogeneity and several new generic entities have been described based on 16S rRNA gene sequence analyses from populations with similar morphology. During a study of the diversity of Phormidioideae (Phormidiaceae, Oscillatoriales) in Brazil, ten Phormidium-like strains from south-eastern and mid-western regions were isolated in monospecific cultures and submitted to polyphasic evaluation (morphological, ecological and molecular studies). The populations studied presented homogeneous morphology (trichomes straight, not attenuated and apical cell rounded or obtuse), differing mainly in cell length from the type species of the genus Phormidium (Phormidium lucidum Agardh ex Gomont) and occurring as three morphotypes. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the populations studied, with European Phormidium aerugineo-caeruleum (Gomont) Anagnostidis & Komárek strains, were placed together in a very distinctive and highly supported clade. Thus, the set of characteristics of the strains resulted in the recognition of the new genus Potamolinea Martins et Branco with two species: Potamolinea magna as the type species (strains 47PC and 48PC) and Potamolinea aerugineo-caerulea (Gomont) Martins et Branco (strains 1PC, 2PC and 38PC). These two species plus one still undetermined lineage,Potamolinea sp., are morphologically and genetically distinguishable, whereas the secondary structures of the D1-D1', box-B and V3 regions were conserved within each one. The generic name and specific epithets of the new taxa are proposed under the provisions of the International Code of Nomenclature for algae, fungi and plants.

Aliterella atlantica gen. nov., sp. nov., and Aliterella antarctica sp. nov., novel members of coccoid Cyanobacteria.

Two Cyanobacteria isolated from South Atlantic Ocean continental shelf deep water and from a marine green algae inhabiting the Admiralty Bay, King George Island, Antarctica were investigated based on morphological and ultrastructural traits, phylogeny of 16S rRNA gene sequences, secondary structure of the 16S-23S internal transcribed spacer regions and phylogenomic analyses. The majority of these evaluations demonstrated that both strains differ from the genera of cyanobacteria with validly published names and, therefore, supported the description of the novel genus as Aliterella gen. nov. The identity and phylogeny of 16S rRNA gene sequences, together with the secondary structure of D1D1' and BoxB intergenic regions, further supported the two strains representing distinct species: Aliterella atlantica gen. nov., sp. nov. (type SP469036, strain CENA595T) and Aliterella antarctica sp. nov. (type SP469035, strain CENA408T). The phylogenomic analysis of A. atlantica sp. nov. CENA595T, based on 21 protein sequences, revealed that this genus belongs to the cyanobacterial order Chroococcidiopsidales. The isolation and cultivation of two geographically distant unicellular members of a novel cyanobacterial genus and the sequenced genome of the type strain bring new insights into the current classification of the coccoid group, and into the reconstruction of their evolutionary history.

Proposal of Ancylothrix gen. nov., a new genus of Phormidiaceae (Cyanobacteria, Oscillatoriales) based on a polyphasic approach.

During a study about the diversity of Phormidioideae (Phormidiaceae, Oscillatoriales) in Brazil, seven strains from southern and southeastern regions were isolated in monospecifc cultures and submitted to polyphasic evaluation (morphological, ecological, cytological and molecular studies). The populations studied were found to be morphologically similar to Kamptonema (filaments narrowed and bent at the end) and cytologically different (thylakoids' arrangement - radial distribution in Brazilian strains and parietal distribution in Kamptonema). The original habitats were very diverse among the Brazilian strains (freshwater, wet soil and barks of trees). Phylogenetic analysis based on 16S rRNA gene sequences revealed that the strains were placed together in a very distinctive and highly supported clade. Thus, the set of characteristics of the strains resulted in the recognition of the new genus Ancylothrix Martins et Branco gen. nov. with two species [Ancylothrix rivularis gen. nov., sp. nov. (type species) and Ancylothrix terrestris sp. nov.], distinguishable by differences in genetic and ecological characteristics and described under the provisions of the International Code of Nomenclature for algae, fungi and plants. Secondary structures of D1-D1', box-B and V3 regions were conserved in A. rivularis gen. nov. sp. nov. and more variable in A. terrestris sp. nov.

Lista de Cyanobacteria do Estado de São Paulo / Checklist of Cyanobacteria from São Paulo State, Brazil

Com base no levantamento bibliográfico realizado sobre as cianobactérias citadas para o Brasil e para o Estado de São Paulo em particular, além de consulta à lista de espécies da flora brasileira e aos bancos de dados de coleções paulistas, encontramos um total de 460 espécies citadas para o Brasil e 378 para o estado de São Paulo. Considerando que o grupo tem ao redor de 2800 espécies, estes números representam bem menos de 20% das espécies conhecidas. Assim, frente a diversidade de ambientes e habitats existentes nos biomas tropicais/subtropicais, o reduzido número de espécies já conhecidas indica que certamente essa biodiversidade está subestimada e deve ser muito maior do que identificamos até agora.

Based on the literature about the cyanobacteria from Brazil and particularly from São Paulo State, the list of Brazilian flora and the data bank of herbaria collections, a total of 460 species were referred to Brazil and 378 to São Paulo State. Taking into account that the group of cyanobacteria presents around 2800 species, these numbers represent much less than 20% of the known species. Considering the diversity of environments and habitats in the tropical/subtropical biomes compared to the reduced number of known species, this biodiversity is certainly underestimated and should be much larger.