Planktic morphospecies of the cyanobacterial genus Anabaena = subg. Dolichospermum -: 1.: part:: coiled types

The traditional cyanobacterial genus Anabaena contains several groups of morphospecies, which should be classified in different genera according to modern phenotypic and molecular criteria. The separation into several clusters was confirmed by 16S rRNA sequencing. The generic name Anabaena must be maintained for the benthic species without gas vesicles, the type species of which is Anabaena oscillarioides. The planktic types are divided also in several sub,clusters; one of them can be provisionally designated as subg. Dolichospermum THW. ex WrTTR. et NORDST. 1889 with the type species Anabaena flos-aquae [LYNGB] BREB. ex BORN. et FLAH. 1888. The taxonomy of this cluster, which contains types with coiled as well as straight filaments, is not yet satisfactory solved. The interspecific features are particularly problematic. However, the review of stable coiled morphotypes from the subg. Dolichospermum which are known and repeatedly occur in natural populations, is presented in this article. This review should help to the orientation of phenotype diversity of coiled Dolichospermum-types, especially in populations occurring in natural habitats.