On the occurrence of Laurencia pyramidalis Bory ex Kützing (Rhodophyta, Rhodomelaceae) in the Mediterranean Sea

The occurrence of Laurencia pyramidalis (Ceramiales, Rhodomelaceae) at Castelsardo (Sardinia, Italy) is reported, representing the first confirmed record of this species from the Mediterranean Sea. A study of tetrasporic specimens has shown that production of tetrasporangia is restricted to the 4th pericentral cell in L. pyramidalis, in contrast to L. obtusa (a species that L. pyramidalis has, in the past, been synonymized with) in which tetrasporangia are produced from both the 3rd and 4th pericentral cells.