Grateloupia doryphora (Montagne) Howe, originally described from Peru, has repeatedly been reported as an invasive species in Atlantic and Mediterranean waters. Various attempts to explain this species’ route of invasion have, so far, been unsatisfying. In the present paper we provide new evidence on the basis of comparative rbcL sequence analysis and morphology that this invasive species in the NE and NW Atlantic corresponds to G. turuturu Yamada, originally described from Japan. The true origin of this alga follows a well-recognized trend of invasive marine organisms that have on various occasions colonized the Atlantic and Mediterranean Sea from Pacific NE Asia.

Key words: Grateloupia doryphora, Grateloupia turuturu, invasive alga, rbcL, Rhodophyta, taxonomy