Chrysymenia wrightii (Rhodymeniales, Rhodophyta) - a new non-native species for the European Atlantic Coast

Chrysymenia wrightii, originally described from Japan, was found for the first time from the European Atlantic coast. It was collected in several subtidal rocky bottom habitats (9-14 meters depth) of the Ría de Arousa (Galicia, NW Spain). In this work, a description of Galician gametophytic and tetrasporophytic plants is provided. They are similar to the Mediterranean and Japanese plants. DNA sequence data of materials from Galicia and Korea were investigated using nuclear SSU and ITS1-5.8S-ITS2 rDNA and plastid rbcL sequences. No genetic variation was observed in the SSU, and only one substitution was detected in ITS and rbcL data between Galician and Korean samples, respectively. Our molecular data indicate that the Galician populations of C. wrightii are probably due to a recent introduction event from the northwest Pacific. Despite the fact that C. wrightii was formerly recorded as a new non-native species from a Mediterranean hotspot (Thau Lagoon, 1987-1989), it was never reported for the European Atlantic coast. After 30 years of its first report in the Mediterranean Sea, the simultaneous occurrence of C. wrightii in four subtidal localities of NW Spain suggests that this species may have colonized the region unnoticed for several years which may be related to its subtidal habitat and short life cycle. Similarly to the Mediterranean Sea, the introduction of C. wrightii on the European Atlantic coasts could be enhanced by the intensive aquaculture widely spread along the Galician coast. Curiously, C. wrightii is apparently restricted to both areas, the Ría de Arousa and the Thau Lagoon. In addition, many non-native species markedly represented in Galicia since the 1980’s were firstly reported in the Ría de Arousa. Consequently, the Ría de Arousa should be considered an outstanding European Atlantic hotspot of introduced marine species similar to the Solent region (South of England) or the Thau Lagoon.