The complete nucleotide sequences of ssu rRNA genes were determined for nin
e species of Porphyra. Ssu rRNA gene structure was classified into four typ
es by the presence and absence of intron(s). Gene structure even differed w
ithin the same species. Exon nucleotide sequences were identical within the
same species, but differed among species. Seventeen species of Porphyra we
re discriminated by comparing the sequences of these diversified regions, u
sing the results of this study and previous studies.