A new contribution to the alien macroalgal flora of the Ustica Island Marine Protected Area (Tyrrhenian Sea, Italy)

A second record of the non-indigenous species Botryocladia madagascariensis G. Feldmann (Rhodophyta) along the coasts of the “Ustica Island” Marine Protected Area (Tyrrhenian Sea, Italy) is reported. With this additional record for the Sicilian coasts, we provide a description of collected specimens of B. madagascariensis and habitat details. Numerous fertile female gametophytes with cystocarps immersed in vesicles were also observed, for the second time in the Mediterranean Sea, and described.