On the basis of morphological and genetic studies (rDNA ITS1, 5.8S, ITS2, and a 18S rDNA intron), we confirm here
that Caulerpa racemosa var. cylindracea (Sonder) Verlaque, Huisman et Boudouresque, a southwestern Australian
taxon recently introduced into the Mediterranean Sea also occurs in the Canary Islands. This is the first report
of C. racemosa var. cylindracea in the Atlantic. It was observed for the first time in the Canary Archipelago in
1997–1998. The speed and regional scale of expansion (north Atlantic Ocean and the Mediterranean Sea) of this
invasive species appear to be among the most dramatic ever recorded. The possible outcome of this introduction in
the Atlantic is discussed
