Abstract:
Three new species of Sargassum from Vietnam, descriptions of which were previously published in Vietnamese, are redescribed in English, including collections of the species added since 1997. Sargassum cotoense has slender thalli, thick leaves, and very narrow, nearly terete, solitary, and monoecious receptacles. Sargassum phamhoangii has long leaves, langer than its lateral branches, and solitary and dioecious receptacles. Sargassum quinhonense is special because of its phyllocysts and vesicles with earlike expansions. It differs from S. herklotsii Setchell, first described from Hong Kong, in the shape of the leaves and receptacles.
