Aulosira bohemensis sp nov.: further phylogenetic uncertainty at the base of the Nostocales (Cyanobacteria)

Aulosira bohemensis sp. nov. was isolated from a wet meadow soil in South Bohemia, Czech Republic. It shares all the features of the majority of other Aulosira species, including isopolar development with intercalary heterocytes and apoheterocytic akinete development. It differs from all other species through the production of hormogonia perpendicular to the trichome axis following akinete germination. Morphologically the genus Aulosira appears closest to Nodularia, however, phylogenetic placement of A. bohemensis based on 16S rRNA was distant from that taxon. Aulosira falls within the Nostocaceae, with possible sister taxa in Trichormus, Mojavia and Nostoc. Despite the variety of phylogenetic analyses performed, we were unable to obtain bootstrap support for its position in any tree, and its correct phylogenetic position within the Nostocaceae remains unresolved.