A critique of traditional approaches to seaweed distribution in light of the development of vicariance biogeography
An overview of the primary approaches to seaweed biogeography is provided in light of the development of vicariance biogeography. Each approach is discussed with particular regard to the extent to which the methods and objectives are compatible with vicariance. Ecological biogeography is considered an offshoot of ecology and physiology and is more appropriate in determining current distributions of organisms and aspects of physiological ecology rather than the speciation history of monophyletic groups. The R/P quotient of Feldmann and distribution of algal life-forms do not fall within the aegis of vicariance and are considered useful only in a descriptive sense. The examination of seaweed spans propounded by Pielou is considered flawed because of the lack of dependence on monophyletic groups. The floristic school of analysis of many seaweed biogeographers is analagous to the panbiogeography of Croizat, and provides the basis for the more concrete phylogenetic hypotheses that are the basis for vicariance analysis. The latter is considered the best methodology for studying the relationship between patterns of cladogenesis and the distribution of constituent taxa.
Phytogeography of seaweeds of the Azores
189 species of seaweeds have been recorded for the Atlantic archipelago of the Azores (114 Rhodophyceae, 41 Phaeophyceae and 34 Chlorophyceae). Ten of these have been described as endemic algae. The taxonomic status of these “endemics” is far from clear, however. Studies on the relatedness of this seaweed flora to seaweed floras of surrounding areas using clustering methods indicate its intermediary position between the seaweed floras of the subtropical Macaronesian Islands (Canaries Madeira and Salvages) on the one side and those of the warm temperate Eurafrican coasts on the other side. The geographic position of the Azores is NW of the other Macaronesian Archipelagos and thus nearer to the American coast. The Gulf stream may easily transport seaweeds from the Carribean to the Azores. Nevertheless, the number of species of these islands in common with the American Atlantic coast is much lower than with, for example, the W. Mediterranean. Of one group of seaweeds, viz. algae with a strictly warm temperature distribution, not a single species occurs likewise on American coasts. This absence is probably explicable because of the narrow temperature range for survival of these seaweeds. Temperatures of surface waters around the Azores during pleistocene glaciations were not much lower than they are at present. Nevertheless, it can be supposed that a number of seaweeds now occurring in the Azores have become extinct during the last glaciation.
A NOTE ON ANOTRICHIUM TENUE (C. AG.) NÄG. (CERAMIACEAE, RHODOPHYTA) IN SOUTHERN AFRICA1
SUMMARY 
 
The red algal species Anotrichium tenue (C. Ag.) Nag. is reported from localities on the South African and Transkeian coasts. From this area the species has originally been described as Griffithsia secunda Harvey ex J. Ag. From morphological study it is concluded that the Cape material can be distinguished at varietal level, as Anotrichium tenue var. secundum (Harvey ex J. Ag.) nov. comb., nov. stat. It differs from the typical variety by its broader filaments, broader and less branched trichoblasts, and whorls with more numerous spermatangial clusters and tetrasporangia.