Pertti Eloranta

Title consist the term cyanobacteria which is the name given by Stanier in 1970s for the title group of this symposium. His system was based on taxonomy like bacterial practice. Before that name already at least nine names were given since Myxophyceae 1833 for this group. Komarék & Komárková-Legnerová proposed 1992 the name 'cyanoprocaryote’ for this group to avoid confusion among bacteriologists and algologists. Stanier's bacteriological system was based on some morphological, physiological, cytological and biochemical characters of axenic strains and it came soon popular among the experimental scientists. Cyanophyte cultures are useful sources of additional information for taxonomy, but they cannot be the only base for the typification of taxa. Although the botanical Code of nomenclature is not very suitable for cyanophytes, much worse situation would arise if the bacteriological Code were accepted. This is especially true for workers in field disciplines. In fact the more complex cyanophytes are much more similar with real algae. Thus the more practical would be the traditional botanical approach in nomenclature.

The taxonomy and nomenclature systems should be developed to be useful and adequate both for natural materials and pure cultures in laboratories. Although e.g. biochemistry and electron microscopy are modern tools for classification of organisms, the system cannot be based on them only. Classification should be developed so that also identlfication could be done upto reasonable level for practical Scientific purposes. Among cyanophytes/cyanobacteria the criteria for the determitation of species and other taxa are still under discussion and there are not good methods for genotpe identification or delimitation.

Komárek and Anagnostidis have been working since 1980s to build up a new cyanophyte taxonomy and this task is about completed today. However, many genera and species still need revisions and many species are not yet even poperly described. The new system is using older basic monographs as the framework and the authors have presented the complete review of the currently recognised and well defined taxa known from natural biotopes. The new system is using as additional information also the current information from ultrastuctural studies and experimental studies with cultures providing information on the morphological, biochemical and ecophysiological variability and reproduction processes in different taxa.

In the new system by Komárek and Anagnostidis the non-filamentous species are classified to one single order in spite of previous three orders. Thus all unicellular cyanophytes are classified in a single order Chroococcales with 7 clearly distinguishable families. Filamentous forms are classidfied in three orders, Oscillatoriales, Nostocales and Stigonematales. Oscillatoriales is chamracterised by simple filaments without branching or false branching and without heterocytes. Many of the old large genera are completely revised like previous genus Oscillatoria. Order Nostocales comprises filamentous forms with sometimes false branching but with always differentiated cells named heterocytes. Order Stigonematales seems to be morphologically most developed with true brdnching,

heterocytes and complicated life cycles.

Some examples on the principles of the Komárek's and Anagnostidis' system are shown in this presentation.