ATLANTIC KELP SPECIES LAMINARIA LONGICRURIS AND L. SACCHARINA (LAMINARIALES) ARE CONSPECIFIC

The identification of two Atlantic kelp species, Laminaria longicruris and L. saccharina, has been controversial. In order to know if these two species are conspecific, plastid‐encoded RuBisCo spacer and nuclear rDNA ITS sequences were analyzed from twelve individuals of L. longicruris, five of L. saccharina, from Connecticut and Nova Scotia. Four individuals of L. digitata from the above coasts were also analyzed as reference in this study. All RuBisCo spacer sequences from L. longicruris and L. saccharina were exactly identical except for one individual with three different nucleotides. Zero to five different nucleotides of ITS sequences, inculding four polymorphic sites, were found in two species. However, their RuBisCo spacer and ITS sequences are quite different from those of L. digitata. These results strongly suggest that L. saccharina (L.) Lamour. 1813 is conspecific with L. longicruris De La Pylaie 1824 and the different local populations, despite various morphotypes, may be genetically very similar.