THE DISTINCTION OF LAURENCIA-TRUNCATA (CERAMIALES, RHODOPHYTA) IN THEMEDITERRANEAN-SEA FROM LAURENCIA-PINNATIFIDA

A study of Mediterranean specimens identified as Laurencia pinnatifida (Hudson) Lamouroux (Ceramiales, Rhodophyta) showed that they have to be referred to L. truncata Kutzing. This species, occurring also in th e Atlantic, where it was recorded under other names, shows the followi ng main features: axes compressed; epidermal cells elongate, with seco ndary pit connections; medullary cells showing abundant lenticular thi ckenings; tetrasporangia, in parallel arrangement, cut off from the mo ther cells abaxially; antheridial branches unbranched, inserted in dep ressions that do not show a row of axial cells at their base. The spec ies is included in the subgenus Laurencia, section Planae. The new sub genus Saitoa (type species L. pinnatifida), including the section Pinn atifidae J. Agardh emend. Fumari et Serio, is proposed. It is characte rized by lack of secondary pit connections between epidermal cells and by parallel arrangement of tetrasporangia.