The present paper aims at contributing to the knowledge of rhodolith beds by describing the associated macroalgal assemblages of two beds in the western Mediterranean Sea: Gorgona Island in the Tuscan Archipelago National Park and Capo Carbonara Marine Protected Area in the southern Sardinia. Patterns of biodiversity and spatial variability were investigated through a multifactorial sampling design. A total of 84 macroalgal species
was identified, 17 Heterokontophyta, 7 Chlorophyta, 1 Prasinodermatophyta and 59 Rhodophyta. Significant differences between beds were detected and the main species characterizing the two beds were highlighted. The mean number of species per sample was quite low and beta diversity high compared to most Mediterranean macroalgal assemblages.
