A taxonomic, phylogenetic and biogeographic study of the genus Acanthophora (Rhodomelaceae, Rhodophyta)

A cladistic analysis, based on a taxonomic revision is carried out for 7 Acanthophora species using 19 characters. Hypotheses on species affinities are based primarily on morphological characters. Because most species show only few distinctive characters, emphasis was placed on features of spine development, either in relation to vegetative or to reproductive structures. Global distribution of 7 Acanthophora species: viz. A. aokii, A. dendroides, A. muscoides, A. nayadiformis, A. pacifica, A. ramulosa, and A. spicifera, shows a discontinuous pattern. Although widely distributed species are present (A. muscoides and A. spicifera), a disjunct distribution of other species occurs in the Pacific (A. aokii), Indian Ocean (A. dendroides), East-Atlantic region (A. ramulosa), and the Mediterranean and Red Sea (A. nayadiformis). Information on the historical background of the species distribution can be inferred from the obtained phylogenetic tree.