Chamaesiphon fontinalis sp. nov., a new species of unicellular asymmetrically dividing cyanobacteria

Extensive brownish biofilms of algal-bacterial communities were found on stones in streams in the Valdaysky National Park (Russia). The dominant unicellular cyanobacteria in biofilms was determined as Chamaesiphon sp. Although species of this genus often occur in the periphyton of fast-flowing waters, many of them have a geographically limited distribution and occur mainly in mountain streams and rivers in Europe. The strain Chamaesiphon sp. CALU 1864 was isolated from epilithic biofilms in the spring Tekunok. We found that it differs from previously described species not only by its unusual purple pigmentation, but also by morphological features. Molecular-genetic analysis of the primary 16S rRNA sequence and secondary structures of the internal transcribed spacer of the ribosomal operon also confirmed its uniqueness. Phylogenetically, the strain represents an independent lineage on the evolutionary tree. Based on the differences found, which provide strong support for its delineation, we propose to consider strain CALU 1864 as a new species, Chamaesiphon fontinalis sp. nov., first discovered in Russia and described in accordance with the current rules of the International Code of Nomenclature for Algae, Fungi and Plants.