CERAMIACEAE (RHODOPHYTA) OF THE CAPE PROVINCE, SOUTH-AFRICA - DISTRIBUTION IN RELATION TO CONCEPTS OF MARINE PROVINCES

Floristic studies in the Cape Province, South Africa have recorded 87 taxa (including 2 varieties) of the family Ceramiaceae. The distribution of these taxa is discussed in relation to existing concepts of marine floristic provinces in this region. In the approximately 2000 km of coastline between the Orange River in the west and the Kei River in the east, the most dramatic change in floristic composition occurs between the Cape Peninsula and Cape Agulhas. This confirms the position of the `western overlap' described by previous marine biogeographers, separating the temperate west and south coast marine provinces. Further east, a less dramatic but still considerable change from Plettenberg Bay and Port Elizabeth eastward, representing the `eastern overlap', can be distinguished. The latter floristic boundary is much longer than the western transition zone. and it remains uncertain if and where further north, along the sub-tropical Natal coast, there is another relatively homogeneous flora.