Taxonomic revision of the freshwater cyanobacterium Phormidium murrayi = Wilmottia murrayi

The cyanobacterial genus Phormidium is polyphyletic, as follows from recent molecular and phenotypic analyses. Several isolated clusters were found also in Antarctic populations (TATON et al. 2006, TATON et al. 2010, STRUNECKY et al. 2010b). A few of them have already been described or revised on the generic level (e.g., Phormidesmis, Microcoleus). One of the separate clusters belongs to a group of strains identified traditionally as Phormidium murrayi, described from the Antarctica originally in 1911 as Lyngbya murrayi by W. et G.S.WEST. We evaluated 23 morphologically similar strains or populations resembling Ph. murrayi from the Antarctica and few other geographical regions; 6 of them were studied by us by molecular methods. Morphological characteristics and 16S rDNA similarity corresponding with typical Ph. murrayi were shared mostly by the specimens from the Antarctica. Molecular analyses confirmed that Ph. murrayi represents a special taxonomic group (on the generic level) inhabiting commonly shallow freshwater classified as a special genus in cyanobacterial taxonomy (Wilmottia gen. nov.) according to the recent polyphasic approach. The type species of Wilmottia, W murrayi, was determined up to now to be characteristic for the Antarctica. Other phylogenetically and morphologically similar types from other regions represent possibly different taxa (species) of the same generic unit. The specific status of similar or related strains from other regions should be therefore solved in the future.