Article

Both floristic and geobotanic characteristics of the benthic macroalgal flora of Italy are discussed. The flora, obtained from Iiterature records since 1950, consists of 869 (510 Rhodophyta, 205 Phaeophyta and 154 Chlorophyta) taxa accepted under current taxonomy. Ceramiales, Fucophyceae and Chlorophyceae of such a flora were separately compared with corresponding taxonomic lists of the following Mediterranean regions: Spain; France; Greece and Turkey; Libya, Egypt and Levant States (Syria, Lebanon and Israel); Morocco, Algeria and Tunisia. From that comparison it appears that the benthic macroalgal flora of the Italian coast is the richest in species, probably because it was the most studied especially in the last years. Hierarchical c1ustering of the above lists based on both floristic and phytogeographic characteristics were carried out and the results were expressed in dendrograms from which a noti ceable floristic similarity among the lists can be drawn since the lists are Iinked above the 50% level of importance excepting those of the Libya, Egypt and Levant States (30 to 50%), which could represent a floristic discontinuity. However, such a discontinuity, due to the low number of species recorded in that area, could depend besides on the insufficient floristic knowledge, on both geomorphologic characteristics of coast and paleoclimatic events like sapropel crises. But, from dendrograms based on chorological spectra, it results a more marked degree of similarity among the Iists that are linked above the 75% level of importance.