The red algal genus Stenogramme was described by Harvey (1840) for entities having flattened, dichotomously branched thalli with cystocarps borne in narrow, linear sori resembling an interrupted midrib on blades, and with isomorphic tetrasporophytes with scattered circular to irregular tetrasporangial nemathecia. In the current literature, the most common species listed is Stenogramme interrupta (C. Agardh) Montagne ex Harvey 1848, said to have a worldwide distribution in temperate seas. DNA sequences from three molecular data sets (chloroplast-encoded rbcL, and nuclear-encoded ITS and LSU rDNA) instead reveal that the genus is more species-rich than is currently appreciated, and that several species go under the name S. interrupta. The latter species, described from Cadiz, Spain, is found to be restricted to the Eastern Atlantic. The name Stenogramme californica Harvey 1840, the type species described from the Pacific coast of North America, is reinstated for members from California and Oregon. S. rhodymenioides Joly et Alveal 1969 is reinstated for the entity from Chile. The range of S. phyllophoroides (J. Agardh) Millar 1990 described from northern N.S.W., Australia, is expanded to accommodate the taxon from South Australia referred to as S. interrupta. S. leptophylla J. Agardh 1885 is a distinct S. Australian species. A new name needs to be provided for the New Zealand taxon. The genus also comprises a new entity (sterile) from Alaska, and a new (sterile) species from offshore Louisiana. Stenogramme is a well-defined monophyletic genus, but its position within the Phylophoraceae remains equivocal.

Key words: ITS rDNA, LSU, Phyllophoraceae, rbcL, Red Algae, Rhodophyta, Stenogramme