The seaweed vegetation of the Sithonia Peninsula (N. Aegean Sea) was investigated during the years 1980-86 and data on the morphology, taxonomy, nomenclature, ecology and distribution of 265 identified taxa of Rhodophyta, Phaeophyta., and Chlorophyta are presented. More than 80 species are new to the Aegean Sea, and among them the Atlantic rhodophytes Peyssonnelia immersa Maggs & Irvine, Antithamnion ogdeniae Abbott, C hondria collinsiana Howe, Chondria polyrhiza Coll. & Herv., and phaeophytes Mesogloia lanosa P. & H. Crouan, Microspongium gelatinosum Reinke, and Ralfsia clavata (Harv.) P. & H. Crouan, are new to the Mediterranean flora. Ten species, belonging to the genera Mesophyllum Lemoine, Phymatolithon Foslie, Haematocelis J. Ag., Peyssonnelia Decne, Laurencia Lamour., Chondria C. Ag., Seirospora Harv., Myrionema Grev., Myriactula 0. Kuntze, and Bryopsis Lamour., are provisionally described under their generic names as identification to species level requires critical revision of the genera. A survey of the seaweeds of the Aegean Sea is given for the first time and in this connection many previously recorded taxa are excluded or reduced to synonyms, and two new combinations are made: Spongites notarisii (Dufour) Athanasiadis and Balliella cladoderma (Zanardini) Athanasiadis. It shows that at least 440 recognized species and taxa of lower rank occur, of which about 20% are Mediterranean endemics. Most of the taxa (ea 78 %) have a Mediterranean-Atlantic origin. Within the area investigated, the distribution of the species identified appears to be similar to that described elsewhere in the Mediterranean, although differences occur in abundance and size of particular species as well as in the representative seaweed populations. A large number of taxa falls within the group of rare species, which are usually characterised by a depauperate thallus too. Cystoseira corniculata (Wulfen) Zanard. is the dominant macroalga on the Makedonian coast and is here considered to be the most characteristic element of the local marine vegetation. Special emphasis is given to representatives of the tribe Antithamnieae (Ceramiales, Rhodophyta) and a revision of the group in the Aegean Sea is reported. In addition to the traditional taxonomic criteria, biosystematic methods are used including sexual compatibility, chromosome number, and controlled laboratory culture to test the range form of morphological features. Three genera are recognized, namely Antithamnion Nageli, Pterothamnion Nageli, and Bailiella Itono & Tanaka. They are characterized by apical, lateral, and intercalary carposporophyte position respectively. A study of the type species of the genus Antithamnion, A. cruciatum (C. Ag.) Nag., reveals the occurrence of a distinct entity in southern Scandinavian and the establishment of the variety Antithamnion cruciatum var. scandinavicum Athanasiadis is proposed. |
