Original paper

What are the cyanobacterial genera Cyanothece and Cyanobacterium? Contribution to the combined molecular and phenotype taxonomic evaluation of cyanobacterial diversity

Komárek, Jiří; Cepák, Vladislav; Kaštovský, Jan; Sulek, Josef

Abstract

Isolated strains of the cyanobacterial genus Cyanothece Kom. 1976 (related to another genus Cyanobacterium Rippka et Cohen-Bazire 1983) were repeatedly included in molecular evaluations of unicellular cyanobacteria. However, this group was found heterogeneous, inconsequences appeared in results and in strain designations, and sometimes the taxonomic positions following from molecular studies of strains and from phenotype analyses of natural populations were not in agreement. In this article, the criterion of ultrastructural characters (nucleoids, thylakoid pattern) is introduced to the synthesis and preliminary review of all material concerning the diversity of both genera. The genera Cyanothece (in original sense vs. in later sense of Rippka) and Cyanobacterium were found as independent taxa, which contain several subclusters (characterised by complex of molecular, cytomorphological and ecological features), and which should be classified as units on the "specific level". The taxonomic position of further related, up to now taxonomically not defined and not validly described clusters "Euhalothece" and "Halothece", is discussed. The authors stress the demand of the complex (molecular + biochemical + cytomorphological + ecological) evaluation of diversity for any taxonomic classification.

Keywords

cyanobacteriacyanoprokaryotacyanothececyanobacteriumeuhalothecetaxonomymolecular evaluationphenotype variabilityultrastructurepolyphasic approach