"Cystoseira” hyblaea Giaccone (Ochrophyta, Fucales), a little known but probably widely distributed species in the Mediterranean Sea.

During a recent study of species of the “Cystoseira complex” from the Sicily coasts, a “C.” hyblaea community associated with biogenic crusts of the reef-building worm Sabellaria alveolata (Linnaeus, 1767) (Polychaeta: Sabellariidae) was found on shallow infralittoral bottoms of the southeastern coast near “Isola delle Correnti” (Syracuse). The thalli of “C.” hyblaea show the same characters as those from Tunisia reported by Bouafif et al. (2016), while they only partially correspond to Giaccone’s (1986) description. Therefore, a comparative study between our thalli and Giaccone’s Herbarium specimens held in the Herbarium of the Department of Biological, Geological and Environmental Sciences of the University of Catania (CAT, ex “Herbarium Giaccone”) was made, in order to better characterize the species. The occurrence of “C.” hyblaea in Sicily outside its type locality is confirmed. The “C.” hyblaea community was found in association with a bioconstruction of Sabellaria alveolata. It should be noted that, “C.” hyblaea as well as S. alveolata represent first reports from the study area.