Relation of Pleurocapsa cuprea Hansgirg to the genus Hildenbrandia (Rhodophyta)

Pleurocapsa cuprea HANSGIRG 1892 was described as a cyanobacterial species from mountain streams in the southern Tyrol and Bohemia, and commonly identified from natural localities. Diagnostic features include a verrucose surface and copper colour of the colonies, with occasional occurrence of pseudodichotomic branching of the thallus. Natural material of P. cuprea was studied recently and compared with the type material from a collection of cryptogams (Natural History Museum Vienna). The morphology of its macroscopic red patches (colonies) and cells in particular are similar those of the rhodophyte Hildenbrandia rivularis. This paper presents a comparison of morphological and molecular characters of P. cuprea and H. rivularis and the partial molecular sequence data of P. cuprea. It also reports results from 4,6-diamidino-2-phenylindole staining, transmission electron microscope analyses and analyses of pigments. According to the results of variable analyses, P. cuprea is an eucaryotic alga and should be classified to the Rhodophyta, close to the group of the freshwater species of the genus Hildenbrandia as a special species of this genus. The relationships between P. cuprea and H. rivularis are discussed.