In this study, all Cystoseira taxa (at species and infraspecific level) reported from the Mediterranean Sea by several authors are evaluated. A total of 41 taxa (at species and infraspecific level) are reported as current from the Mediterranean Sea (Table 1). The photographs are given from the extensive collections of Cystoseira taxa by Gerloff and Nizamuddin in the Herbarium of the BGBM [B] (Berlin, Dahlem), personal herbaria by E. Takn [E.T.] and M. Öztürk [M.Ö.] (Celal Bayar University, Turkey) and collections by G. Furnari [G.F.] and M. Cormaci [M.C.] held in the Herbarium of the University Catania, Italy (CAT).
Species of the brown alga genus Cystoseira are important elements of the marine flora in the Mediterranean Sea. Ribera et al. (1992) reported 47 taxa to occur in the Mediterranean Sea, including 19 endemics (Amico, 1995). Gómez Garreta et al. (2001) stated that Cystoseira includes about 50 species, the majority occuring in the Mediterranean Sea or Atlantic-Mediterranean. Several studies have been made on the Mediterranean Cystoseira. Some of these are by Sauvageau (1912), Hamel (1939), Ercegovic (1952), Güner (1974), Zinova and Kalugina (1974), Gerloff and Nizamuddin (1975a, 1976), Giaccone (1985), Amico et al. (1985), Athanasiadis (1987), Öztürk (1996), Gómez Garreta et al. (2001) and Takn and Öztürk (2007). Twenty-four taxa (at species and infraspecific level) have been reported to occur in Turkey by Takn and Öztürk (2007). Furnari et al., (2010) reported 41 taxa of Cystoseira from Italy. In this study, Cystoseira brachycarpa J. Agardh emend. Giaccone var. brachycarpa, Cystoseira spinosa var. compressa (Ercegovic) Cormaci et al. and Cystoseira spinosa var. tenuior (Ercegovic) Cormaci et al. are reported for the first time from Turkey.