Reexamination of the genus Pterocladiella (Gelidiaceae, Rhodophyta) in Korea based on morphology and rbcL sequences

Although Pterocladiella is a well-known agar-producing red algal genus, its taxonomy in Korea appears to be confused. In the present study, we demonstrate the occurrence of Pterocladiella nana and P. tenuis, as well as P. capillacea in Korea on the basis of morphological and plastid rbcL sequence comparisons. P. capillacea commonly occurs along the coasts of Korea and has regular pinnate branches with abundant second-order branches, growing up to 10 cm in length. P. nana occurs in the intertidal zone of Jeju and is distinguished by the small size of its thalli (up to 5 cm) and regular branches with up to third-order branches. P. tenuis is distributed mostly subtidally on the southern coast of Jeju and has irregular branches with rarely second-order branches, growing up to 19 cm in length. We determined rbcL sequences from 19 specimens (15 from Korea and four from France) and downloaded 28 sequences from GenBank. Analyses of all 47 rbcL sequences revealed that each of three species was consistently resolved. P. capillacea and P. tenuis always formed a sister clade with P. nana at the base. Given that 12 rbcL haplotypes from 28 specimens of P. capillacea have been found to date, analysis of a fast-evolving gene from across the range of the species should highlight its genetic diversity.