Current trends and prospects for cyanobacterial taxonomy – are only cultured populations enough?

Describing new taxa for Cyanobacteria is becoming more common in the last years following the increase of taxonomical studies using the polyphasic approach. The improvement of the phylogenetic analysis led to more precise knowledge about the relationships between taxa, but besides this, authors are neglecting the morphological data of populations from environmental samples, describing organisms growing only under culture conditions. Polyphasic approach considers the 16S rRNA gene phylogeny as the main criterion to distinguish taxa for Cyanobacteria, but there's not enough data to consider that the morphological evaluations from environmental populations are not relevant.