Laurencia kangjaewonii sp. nov. (Ceramiales, Rhodophyta) from Korea

Laurencia kangjaewonii sp. nov. (Ceramiales, Rhodophyta) is described from subtidal habitats of eastern and southern Korea. Plants are strongly compressed throughout, with alternatedistichous branching. Vegetative axial segments have two pericentral cells. Spermatangial branches are produced from adaxial lateral branches borneon suprabasal cells oftrichoblasts that arise from axial cells in terminal cup-shaped spermatangial pits. Other features of the male reproductive structure are typical of the ‘trichoblast’ type. Procarp-bearing segments cut off five pericentral cells, the fifthof which becomes the supporting cell. Procarps have a four-celled carpogonial branch with two sterile groups,and the post-fertilization development is essentially the same as in other species of Laurencia. Tetrasporangia are produced from 3(4) additional pericentral cells in fertile segments. Laurencia kangjaewonii shares several features with the subgenera Laurencia and Chondrophycus, including: parallel arrangement of tetrasporangia (subgen. Laurencia) and absence of secondary pit-connections between adjacent epidermal cells (subgen. Chondrophycus). The vegetative axial structure and tetrasporangialfeatures strongly suggest that the new species is more closely allied to the subgenus Chondrophycus than to the subgenus Laurencia. Anatomical characters of the new species are compared with those of other related species.