Multiple introduction events expand the range of the invasive brown alga Rugulopteryx okamurae to northern Spain

The brown alga Rugulopteryx okamurae is one of the most recent and aggressive marine invaders known, with a non-native range that spans from the western Mediterranean to the southern Iberian Peninsula, and the European Macaronesian archipelagos. Here, we provide the first record of its presence at three disjunct areas from northern Spain, supported by morphological and molecular evidence. Rugulopteryx okamurae was discovered in the port of Bilbao in the northeastern Atlantic of Spain, more than 1200 km away from the nearest invaded location previously known. It was also found at two separate areas in northwestern Spain: San Amaro, a small inlet at the entrance of the port of A Coruña, and Monteferro-Playa América, a site close to the port of Vigo. In two areas, R. okamurae was found to cover up to 100 % of the bottom, suggesting that it may behave as an aggressive invader in northern Spain. Our findings confirm the propensity of R. okamurae for long-distance dispersal and reveal that this invader is expanding its range northwards along the European Atlantic coast. • The invasive of Union concern R. okamurae has reached North Atlantic Spain. • The invaded range edge shifted 5° North. • Multiple independent introductions likely explain the disjunct distribution. • R. okamurae is very aggressive in some locations, completely covering the substrate.