Scytonema santannae, a new morphospecies of Cyanobacteria from the Atlantic rainforest, southeastern Brazil

(Scytonema santannae, a new morphospecies of Cyanobacteria from the Atlantic rainforest, southeastern Brazil.) The genus Scytonema (Cyanobacteria) is one of the most common and important components of terrestrial biofilms in tropical and subtropical areas, mainly because of its nitrogen fixation capability and wide diversity of species. In the Brazilian Atlantic rainforest, Scytonema populations are frequently found growing on rocks, bark of trees, soil and among mosses, but are still underestimated and poorly characterized. In this article, we describe a new terrestrial morphospecies of Scytonema collected in the State Park of Ilha do Cardoso, an island located in the subtropical area of the Atlantic rainforest, State of São Paulo. The main features of the new species are remarkable mosaic-ornate sheaths and typical epiphytic growth on mosses on wooden substrates. The developmental process of mosaic-ornate sheaths has not yet been clarified, and hitherto, their occurrence was known only for two taxa (several populations of S. cf. stuposum and Brasilonema ornatum).