New record of Gayralia kuroshiensis (Ulotrichales: Chlorophyta) in Korea based on morphological and molecular analyses

Monostromatic algae, Monostroma and Gayralia, are taxonomically complex, with several nomenclatural changes over the past years owing to indistinguishable morphological features. Several Monostroma species were recently transferred to the genus Gayralia based on their ontogeny and molecular analysis. There is no record of the occurrence of Gayralia in Korea, whereas three species of Monostroma have been reported. We conducted a molecular analysis based on the nuclear ribosomal internal transcribed spacer region of the specimens from Jeju, Korea, that we considered to be included in the genus Monostroma. The specimens from this study and five sequences of Monostroma nitidum downloaded from the GenBank were conspecific with Gayralia kuroshiensis from Japan but distinct from the M. nitidum syntype from Australia. G. kuroshiensis has a single, expanded, laminar, monostromatic thallus that is light to mid-green. The thallus thickness in the marginal regions was similar to that of G. kuroshiensis from Japan, with an undulate shape and no marginal teeth. The cells in surface view were in groups of two, rectangular to polygonal in shape, with one to three pyrenoids per cell. Based on the morphological and molecular analyses, we report a new record of G. kuroshiensis in Korea.