LAUSR

Abstract Freshwater red algae are important components of the algal flora in streams and rivers with high water quality. The order Batrachospermales is the most species-rich portion of the red algal taxa reported throughout North America. We investigated 30 stream segments in South Carolina for the presence of freshwater red algae classified within the Batrachospermales. We collected a total of 50 specimens representing 7 genera and 9 species. We documented Batrachospermum gelatinosum, B. turfosum, Kumanoa skujana, Montagnia australis, Sheathia americana, S. heterocortica, Sirodotia suecica, Tuomeya americana, and Virescentia viride-americana. We observed M. australis and T. americana from the greatest number of streams and in multiple years from the same site. We observed V. viride-americana in 3 streams; our specimens represent the only new record for the state. We generated DNA sequence data of the rbcL gene or gleaned it from the literature for 8 of the 9 taxa identified in the study and confirmed their morphological identification. We collected stream temperature, pH, and conductivity data from sites where we collected 6 of the taxa (Batrachospermum gelatinosum, B. turfosum, M. australis, Sheathia americana, T. americana, and V. viride-americana). Our records were within previously reported ranges for these taxa, although water temperatures tended to be higher than those in previous reports. Present data for the diversity of Batrachospermales in South Carolina represent 64% of the generic/infrageneric and 20% of the species diversity known for North America. This diversity may still be an underestimation of what might be detected by future studies that target more specialized habitats; taxa that are known from neighboring states but not yet reported from South Carolina might be discovered.