First record of Caulerpa cylindracea (Caulerpaceae, Chlorophyta) in Andalusia (Southern Spain)

Three different species of Caulerpa (Caulerpaceae, Chlorophyta) co-occur in the Mediterranean Sea: two of them are found at the central-eastern basin and are typically considered non aggressive components of the Lessepsian flora [(C. chemnitzia(Esper) J.V. Lamouroux and C. racemosa var. lamourouxii (Turner) Weber-van Bosse f. requienii(Montagne) Weber van Bosse)]; a third taxon, C. cylindracea Sonder has aggressively expanded its range since its first observation in 1990, and it is nowadays reported from nearly all the Mediterranean countries. We report a population of C. cylindracea from Almería (Andalusia, Southern Iberian Peninsula) at −30 m depth as to be the westernmost record of the invasive variety on the Mediterranean European coast. Therefore, we made use of morphological description and molecular phylogenetics to provide a complete identification of this invasive seaweed in Southern Spain. Our findings are discussed in light of the composition of the receptor communities, such as maërl bed, edges of Posidonia oceanica (Linnaeus) Delile, and their ecology. Our results confirmed the suggested directionality of the invasive pathway to be westward to the Strait of Gibraltar, mainly supported by sea currents and vectors of anthropogenic origin.