Nuclear rDNA sequences from Ballia prieurii support recognition of Balliopsis gen. nov. in the Batrachospermales (Florideophyceae, Rhodophyta)

Abstract

Nuclear small-subunit and partial large-subunit rDNA sequences were determined for the freshwater rhodophyte species Ballia prieurii, from northern Brazil, to assess its relationship to the marine species that have recently been transferred to a new order, Balliales, in the Florideophyceae. Ballia prieurii unequivocally associated with species of the freshwater order Batrachospermales, rather than with the marine Balliales, in all molecular analyses. In addition to habitat, asexual reproduction by monosporangia in the freshwater species of Ballia is consistent with inclusion in the Batrachospermales and has not been reported for any marine Ballia species, which reproduce exclusively by asexual tetrasporangia. As B. prieurii is distinct in morphological and molecular features from all other members of Batrachospermales, a new genus Balliopsis G.W. Saunders & Necchi gen. nov. is proposed to accommodate this species, which becomes Balliopsis prieurii (Kützing) G.W. Saunders & Necchi comb. nov. Previously published morphological and anatomical observations indicate that a second freshwater species of Ballia, B. pinnulata, is clearly related to Balliopsis prieurii and it too is transferred to the new genus. The familial affinities of Balliopsis are discussed, but Balliopsis is left as a genus Incertae sedis within the Batrachospermales.