Morphology and vegetative reproduction of the introduced species Hypnea cornuta (Rhodophyta, Gigartinales) in the Mar Piccolo of Taranto (Italy, Mediterranean Sea)

Hypnea cornuta, a species previously introduced into the eastern Mediterranean Sea, has been discovered recently in the Mar Piccolo of Taranto (southern Italy). The specimens are in good agreement with Indo-Pacific descriptions and reference material. It is highly probable that H. cornuta has been introduced either from eastern Mediterranean or Indo-Pacific populations via ship traffic or shellfish transfers (mussels). Since being introduced, H. cornuta has given rise to a stable both attached and free-floating population throughout the Mar Piccolo. Both attached and unattached plants are described. Field and culture observations have confirmed the reproductive role of the stellate branchlets as propagules. Vegetative reproduction both by propagules and fragmentation seems to be the only mode of reproduction in the Mar Piccolo.