Open Access

Jiří Komárek

• The cyanoprokaryotic genus Romeria is traditionally classified as the simplest filamentous cyanobacterium, occurring scarcely in freshwater reservoirs. Three species were described originally, which are known from the temperate zone, and which are usually cited in all identification manuals of this cyanoprokaryotic group. However, other species were found recently, also in other biotopes (benthos, cryoseston, marine plankton), and now the number of registered species increased to 19. The problem is, that they were not yet isolated in culture, and nothing is known about ultrastructure and molecular characters of any Romeria species. Recently, two mass developments of two planktic species were found in freshwater reservoirs in Brazil and in Czech Republic, which enabled, at least, the study of their morphological variability and cell structure. It was found, that Romeria is evidently very interesting cyanobacterium with close relations to other simple filamentous species, as well as to simple coccoid types living in solitary, rod-like cells. The review of the whole genus, which is included in this article, is necessary for further research of this important cyanobacterial type.