A new genus of filamentous epipelic cyanobacteria, Johansenia.

The cyanobacterial genus Komvophoron frequently inhabits sediments in stagnant freshwater among which K. hindakii and K. constrictum dominate. However, morphological heterogeneity within populations of K. constrictum necessitated a closer examination of this species’ taxonomic position. Based on Szafer’s (1910) concept, Oscillatoria constricta, later transferred to K. constrictum, is an oscillatorean cyanobacterium and does not form heterocytes. However, Geitler (1925) considers this species to be a member of the genus Anabaena due to the presence of heterocytes in some populations. We studied natural and cultured populations using morphological and molecular characters (e.g. the 16S rRNA gene and ITS region) and found that the genus Komvophoron is polyphyletic. Thus, we establish a new genus Johansenia gen. nov. based on Szafer’s original concept of Oscillatoria constricta. While Johansenia is phylogenetically related to the genera Spirulina and Geitlerinema (BBD strains), members of the genus Komvophoron (K. hindakii, K. kgarii) are related to members of the family Gomontiellaceae.