Sebdenia monnardiana

Küpper, Frithjof C., Tsiamis, Konstantinos, Johansson, Niko Rainer, Peters, Akira F., Salomidi, Maria, Manousakis, Leonidas, Kallergis, Manolis, Graham, Michael H., Kinlan, Brian, Mystikou, Alexandra, Žuljević, Ante, Nikolić, Vedran, Gerakaris, Vasilis, Katsaros, Christos & Panayotidis, Panayotis, 2019, New records of the rare deep-water alga Sebdenia monnardiana (Rhodophyta) and the alien Dictyota cyanoloma (Phaeophyceae) and the unresolved case of deep-water kelp in the Ionian and Aegean Seas (Greece), Botanica Marina (Warsaw, Poland) 62 (6), pp. 577-586 : 583

Sebdenia monnardiana

Sebdenia monnardiana is known only from circalittoral habitats of the western Mediterranean – but not yet from the eastern Mediterranean. No SSU sequences, only rbc L sequences are available for S. monnardiana so far.

The finding presented here constitutes a new record for Greece and, indeed, the entire eastern Mediterranean. The Sebdeniaceae was erected by Kylin (1932) in order to accommodate Sebdenia monnardiana originally described from the North African coast of the western Mediterranean. Athanasiadis (2002; p. 120) reported it to be “the largest Mediterranean red alga, reaching 1 meter in diameter”. Compared to this, the specimen reported here (of only about 10 cm size) is very small. The SSU sequence reported here is the first sequence of this important marker for S. monnardiana , which is significant since S. monnardiana is the type species for the genus Sebdenia and the order Sebdeniales ( Withall and Saunders 2006) , and it is clearly difficult to collect. Our rbc L sequence matches two sequences reported previously for this taxon from Italy (especially AY294395.1 with 99.53% identity for 100% query cover, but also U21600. 1, with 98.94% identity). The specimen corresponding to AY294395 was collected at Lachea Island, near Catania, Italy, by G. Furnari and M. Cormaci in October 1994, and is surely a correctly identified S. monnardiana ( Gavio et al. 2005) . The lower similarity value for U21600 is due to missing data and possible errors in this older sequence; nevertheless it forms a clade with AY294395 and our sequence. Sequence similarity of our specimen with U21600 and AY294395 confirms the morphological identification of our material. In contrast, the sequence EU543493 for an alga from central Italy is problematical. It was submitted to NCBI by R. D’Archino, N. Abdelahad, and G. Procaccini and is only 89.4% identical with EU543493 and 90.6% with our sequence. However, it appears to be a good rbc L sequence (most substitutions are at third base positions) and likely belongs to a related species of as yet unknown identity, which in our