Foliose Grateloupia species are among the most commonly reported introduced species of red algae in European waters. Unequivocal identification at species level, however, has proven exceedingly difficult owing to a relatively low number of clear-cut diagnostic characters and considerable morphological plasticity. Because of their morphological similarity many of these species were placed in synonymy by subsequent generations of phycologists. In the present paper we demonstrate that Gratelopia lanceola, a native European species, is distinct from G. turuturu, a western Pacific alga introduced in European waters. These conclusions are based on comparative gene sequences (rbcL and LSU rDNA) as well as morphology and mycosporine-like amino acid (MAA) signatures. Even though support was largely lacking from rbcL and the combined analysis, G. lanceola was clearly separated from G. turuturu as well as other foliose species. These data, together with earlier accounts on genuine G. doryphora and G. schizophylla, indicate that foliose Grateloupia species display a clear geographic structuring, which has only become obscured by the recent introduction of morphologically similar species (pseudo-cryptic species) along Atlantic coasts and in the Mediterranean Sea. Grateloupia lanceola also showed a different MAA composition when compared with G. turuturu, regardless of spatial-temporal influences. The concentrations were about 3 mg g−1 DW and about 5 mg g−1 DW in G. turuturu and G. lanceola, respectively. The main MAA in Grateloupia lanceola was porphyra-334, which represented almost 100% of these compounds. Only some traces (<1%) of shinorine and palythine were found in this species. On the other hand, the dominant MAA in G. turuturu was shinorine, which represented approximately 92% of the total MAA content; palythine contributed about 7.5% while traces of asterina-330 were also found (Link for PDF).

 

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