In 1980, a study of geographic distribution patterns and geographic affinities of benthic algae of temperate Pacific South America (5-55 degreesS) provided a first characterization of these coasts. High endemism and limited floristic exchange with the Tropical Pacific and with islands in the South Pacific at various distances from the continent were two outstanding features of the marine flora. A partial blockage of species exchange partially accounted for a peculiar latitudinal pattern of species richness that increases with increasing latitudes. In contrast, there was reduced species richness in comparison with other climatically equivalent regions that have contact with more effective routes of migration. Over the last two decades, more than 30 taxonomic and biogeographic studies on this benthic marine flora have been completed, adding a significant number of new records for the area. New studies test the above characterization and indicate that the new data add support to several key aspects of the phytogeographic characterization of this coastline. The relative importance of the various floristic components at different latitudes, the isolated character of this flora and the latitudinal pattern of increasing species richness to higher latitudes are shown.