The morphology of Griffithsia tomo-yamadae Okamura (Ceramiaceae, Rhodophyta): a little-known species from the northeast Pacific

The ceramiaceous red alga Griffithsia tomo-yamadae was described from the P acific side of Honshu, Japan by Okamura in 1936, based on vegetative and te trasporangial material. Unreported since its original description, the spec ies has recently been found growing in abundance at 1-2 m depths below lowe st tide levels at Geojedo Island off the southeastern coast of Korea. Our d etailed observations confirm the validity of G. tomo-yamadae as a species c haracterized by complanate, flabellate thalli; pseudodi-/trichotomous branc hing; nodal tetrasporangial fascicles that form an inner ring of bearing ce lls surrounded by 8-9 involucral branches, consisting of single basal, cell and two terminal cells; naked spermatangial fascicles; and cystocarps surr ounded by five involucral branches that originate from the hypogenous cell. Sexual reproductive structures are described for the first time and confor m to previous reports of the genus.