Gracilaria vermiculophylla, originally described from Japan, is reported for the first time from European waters where it appears to be restricted to sheltered, estuarine habitats as loose-lying, entangled mats on mud and fine sand, mostly in the vegetative state. The life history was completed in culture in an isolate from Brittany, France. Growth experiments demonstrated the euryhaline and eyrytherm nature of the alga with good growth at 11°C, 19.5°C and 25°C at salinities of 10, 20 and 30 psu, and best growth at 10 psu and 19.5°C. Specimens were sampled from 13 locations in Brittany. In addition, samples of unidentified Gracilaria sp. growing under similar environments were received from Sweden, the Netherlands, Spain and Portugal. Dried specimens of authentic G. vermiculophylla (G. asiatica) from Japan and Korea were examined using DNA sequence data. Mitochondrial DNA cox 2–3 spacer was sequenced in at least one individual from each locality and plastid DNA Rubisco spacer sequences were obtained from many. The rbcL sequence was obtained in the cultured clone, and was only partially sequenced (c. 50–60%) in a few others. No intraspecific variation was seen in the cox 2–3 and Rubisco spacers, and only one difference was seen in rbcL sequences. Isolates of G. gracilis and Gracilariopsis longissima were used for comparisons. It is concluded that the G. vermiculophylla populations in Europe are probably due to a recent introduction event. Some recent reports suggest that the species may also occur on both Atlantic and Pacific coasts of America.
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