Molecular characterization of the red alga Anotrichium tenue (Ceramiales, Rhodophyta) based on topotype material

Anotrichium tenue is a red algal species of the family Wrangeliaceae widely distributed in the Mediterranean Sea and reported in the Atlantic, Pacific, and Indian oceans. Mediterranean and extra-Mediterranean specimens can have similar vegetative and tetrasporangial characters, but they can also be morphologically distinct. In fact, they can have a different number of pedicels per nodal cell and/or a different disposition of tetrasporangia on pedicels. Specimens showing extra-Mediterranean tetrasporangial features were assigned to separate species, subgenera and/or varieties, but the discrimination between these different taxa is still problematic. To solve this taxonomic issue, in this study, we analysed samples of A. tenue from the type locality in Venice (Italy) using the plastidial rbcL and psbA genes as molecular markers, and we compared our results with sequences of A. tenue from Korea. The Venetian entity was genetically different from the Korean ones and most likely represents the genuine A. tenue species.