Cyanomargarita gen. nov. (Nostocales,Cyanobacteria): convergent evolution resulting in a cryptic genus

Two populations of Rivularia‐like cyanobacteria were isolated from ecologically distinct and biogeographically distant sites. One population was from an unpolluted stream in the Kola Peninsula of Russia, whereas the other was from a wet wall in the Grand Staircase‐Escalante National Monument, a desert park‐land in Utah. Though both were virtually indistinguishable from Rivularia in field and cultured material, they were both phylogenetically distant from Rivularia and the Rivulariaceae based on both 16S rRNA and rbcLX phylogenies. We here name the new cryptic genus Cyanomargarita gen. nov., with type species C. melechinii sp. nov., and additional species C. calcarea sp. nov. We also name a new family for these taxa, the Cyanomargaritaceae.     

Rivularia halophila sp. nov. (Nostocales,Cyanobacteria): the first species of Rivularia described with the modern polyphasic approach

ABSTRACT

Natural populations of a Rivularia-like cyanobacterium were collected from the carbonate deposits of the temporarily flooded littoral zone of a hypersaline, high elevation lake, The Laguna Negra, Andes, Argentina. Subsequently, the cyanobacterial strain PUNA-NP3, named after its origin (Puna Volcanic Plateau) was isolated from these Rivularia-like rounded, pillow-like, black microbial mats. None of the previously described species of the genus Rivularia occupy inland, hypersaline aquatic environments. After morphological examination of this strain, we found clear morphological autapomorphies, such as mucilaginous pads at the bases of the young trichomes, wide trichomes and filaments, and uniquely branched trichomes. Furthermore, based on results from 16S rRNA phylogeny and analysis of the 16S-23S ITS region, PUNA-NP3 was found to be an independent lineage of the evolutionary tree. Based on the combination of ecological, morphological and molecular evidence, we name strain PUNA-NP3 Rivularia halophila sp. nov. a new species under requirements of the International Code of Nomenclature for Algae, Fungi and Plants.