Community structure of stream macroalgae in lotic ecosystems from highland grasslands in national parks of southeastern Brazil Orlando Necchi, Luis Henrique Zanini Branco, Ciro Cesar Zanini Branco, Cauê Calvo Necchi, Nadia Martins Lemes da Silva Revista Brasileira De Botanica, 2026 Stream macroalgal communities were sampled at 58 sites across four national parks representing highland grasslands in southeastern Brazil. We assessed taxonomic beta diversity and its components (spatial turnover and nestedness), as well as the influence of selected environmental variables. Environmental conditions varied widely among streams from the different parks, reflecting high environmental heterogeneity, a pattern commonly reported for similar ecosystems worldwide. Cyanobacteria predominated in the flora of the four parks (47.4%), consistent with previous studies, and most species were heterocytous (81.5%), likely reflecting adaptation to low nitrogen availability. Two general patterns evidenced from the analyses: (1) a positive correlation between species richness with percent cover and the Shannon–Wiener diversity index, indicating that the richest and most abundant communities were also the most diverse, in accordance with the patch dynamics concept; and (2) a strong trend of occurrence of species with restricted distributions, with most taxa recorded in only one park or in a few sites within a single park. Taxonomic beta diversity was extremely high (0.96–0.97), showing that spatial turnover (species replacement) accounted for nearly all the observed variation, while the nestedness component was very low (0.01). Thus, community composition was not structured as subsets of a richer community; instead, differences among communities primarily resulted from species replacement driven by environmental filtering. These findings support our hypothesis that the four national parks function as islands, each isolated and represented by its respective mountain range. This isolation results in comparable levels of alpha diversity within parks but markedly elevated beta diversity among them.
Oxynema mangrovii sp. nov., a new filamentous species (Oscillatoriales, Cyanobacteria) from Atlantic forest mangrove Gladys A. Apaza-Castillo, Rafael B. Dextro, Ana P. D. Andreote, Bruno C. E. Souza, Guilherme K. Hosaka, et al. Frontiers in Microbiology, 2026 A cyanobacterial strain isolated from Brazilian mangrove soil and classified as a member of the genus Phormidium was afterward affiliated to the genus Oxynema . To define the species of this Oxynema strain CENA135, we sequenced its whole genome and applied a polyphasic taxonomic approach. This strain, with all the morphological features recognized for the Oxynema genus, had its genome assembled in 11 scaffolds with a total size of 6,235,022 bp, a G + C content of 51.6%, 4,720 protein-coding genes, and five 16S rRNA genes. Genes related to ecological resistance were annotated, demonstrating the relevance of obtaining high-quality genome assemblies from underrepresented habitats. A phylogenomic tree inferred by GTDB-Tk based on the alignment of 120 conserved proteins clustered Oxynema sp. CENA135 together with the strain Oxynema aestuarii AP17 isolated from Indian mangrove soil, and digital DNA–DNA hybridization and average nucleotide identity values between these two strains were 92.8 and 95.78%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences placed the strain CENA135 in a separate and well-supported major clade (100% bootstrap) containing Oxynema species, and its 16S rRNA gene sequence showed identity ≤98.6% compared to the other species of the genus. Moreover, the strain CENA135 had a distinct 16S–23S ITS sequence and secondary structure polymorphisms in comparison to the other Oxynema species, supporting its recognition as a novel species. On the basis of evidence from this polyphasic study, strain CENA135 should be designated as representing a novel species of the genus Oxynema , for which the name Oxynema mangrovii sp. nov. is proposed under the provisions of the International Code of Nomenclature for algae, fungi, and plants.
Phylogenomic analysis of anabaenopsis elenkinii (Nostocales, cyanobacteria) Endrews Delbaje, Ana Paula D. Andreote, Thierry A. Pellegrinetti, Renata B. Cruz, Luis H. Z. Branco, et al. International Journal of Systematic and Evolutionary Microbiology, 2021 The saline-alkaline lakes (soda lakes) are the habitat of the haloalkaliphilic cyanobacterium Anabaenopsis elenkinii, the type species of this genus. To obtain robust phylogeny of this type species, we have generated whole-genome sequencing of the bloom-forming Anabaenopsis elenkinii strain CCIBt3563 isolated from a Brazilian soda lake. This strain presents the typical morphology of A. elenkinii with short and curved trichomes with apical heterocytes established after separation of paired intercalary heterocytes and also regarding to cell dimensions. Its genome size is 4 495 068 bp, with a G+C content of 41.98 %, a total of 3932 potential protein coding genes and four 16S rRNA genes. Phylogenomic tree inferred by RAxML based on the alignment of 120 conserved proteins using GTDB-Tk grouped A. elenkinii CCIBt3563 together with other genera of the family Aphanizomenonaceae. However, the only previous available genome of Anabaenopsis circularis NIES-21 was distantly positioned within a clade of Desikacharya strains, a genus from the family Nostocaceae. Furthermore, average nucleotide identity values from 86–98 % were obtained among NIES-21 and Desikacharya genomes, while this value was 76.04 % between NIES-21 and the CCIBt3563 genome. These findings were also corroborated by the phylogenetic tree of 16S rRNA gene sequences, which also showed a strongly supported subcluster of A. elenkinii strains from Brazilian, Mexican and Kenyan soda lakes. This study presents the phylogenomics and genome-scale analyses of an Anabaenopsis elenkinii strain, improving molecular basis for demarcation of this species and framework for the classification of cyanobacteria based on the polyphasic approach.
Amazonocrinis nigriterrae gen. Nov., sp. nov., atlanticothrix silvestris gen. nov., sp. nov. and dendronalium phyllosphericum gen. nov., sp. nov., nostocacean cyanobacteria from brazilian environments Danillo Oliveira Alvarenga, Ana Paula Dini Andreote, Luis Henrique Zanini Branco, Endrews Delbaje, Renata Beatriz Cruz, et al. International Journal of Systematic and Evolutionary Microbiology, 2021 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.
Biological soil crusts: New genera and species of Cyanobacteria from Brazilian semi-Arid regions NÁTHALI MARIA MACHADO DE LIMA, LUIS H.Z. BRANCO Phytotaxa, 2020 In the uppermost millimeters of soils is commonly found a thin layer of cryptobiotic organisms, including cyanobacteria, microalgae, lichens, mosses, fungi, bacteria and archaea. These communities are called Biological Soil Crusts (BSCs) or biocrusts and perform important ecological functions, mainly attributed to their capacity of providing soil stability and incorporate nutrients through nitrogen and carbon fixation. Among all the organisms found in the biocrusts, the filamentous cyanobacteria Microcoleus vaginatus and M. steenstrupii are the best studied soil colonizers. The genus Microcoleus is considered complex and has been showing close relation with some species of Phormidium. The poor understanding about these two genera is a limit to the description of the real composition of biocrusts and can generate underestimations in the diversity community and the use of wrong organisms in applied projects (e.g. environmental restoration). This work studied eight cyanobacterial populations from Brazilian BSCs sampled in the Caatinga biome. The populations presented Microcoleus-like and Phormidium-like morphologies, but the phylogenetic analyses based on 16S rRNA gene sequences showed that they represent three new genera and six new species of filamentous cyanobacteria associated to the cryptic genera, they are Pycnacronema caatingensis sp. nov., Pycnacronema edaphica sp. nov., Gracilinea arenicola gen. et sp. nov., Marmoreocelis xerophila gen. et sp. nov., Konicacronema caatinguensis gen. et sp. nov. and Trichocoleus caatingensis sp. nov. The generic name and specific epithets of the new taxa are proposed according to the provisions of the International Code of Nomenclature of algae, fungi, and plants.
Polyphasic approach using multilocus analyses supports the establishment of the new aerophytic cyanobacterial genus Pycnacronema (Coleofasciculaceae, Oscillatoriales) Mariéllen Dornelles Martins, Náthali Maria Machado‐de‐Lima, Luis Henrique Zanini Branco Journal of Phycology, 2019 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.
Aerophytic cyanoprokaryotes from the atlantic rainforest region of São Paulo State, Brazil: Chroococcales and oscillatoriales Cryptogamie Algologie, 2009
Ecological distribution of stream macroalgal communities from "Parque Nacional de Itatiaia", states of Minas Gerais and Rio de Janeiro, Brazil Revista Brasileira De Botanica, 2008
