First record of Laurencia chondrioides (Ceramiales, Rhodophyta) from the Mediterranean Sea

The occurrence in the Mediterranean Sea of Laurencia chondrioides, first described from the Caribbean Sea, is reported for the first time. The following characters: i) occurrence of secondary pit-connections between epidermal cells; ii) four vegetative pericentral cells produced per axial segment; iii) tetrasporangia produced by pericentral cells, in parallel arrangement, cut off from the mother cells abaxially; iv) spermatangial branches of trichoblast type; v) cystocarps urceolate to conical with carpostome prominent, are reported for the first time. On this basis, the species is attributed to the subgenus Laurencia. An earlier record from the Canary Islands suggests that this species is unlikely to be a recent introduction into the Mediterranean.