STUDIES ON DASYACEAE - 3 - TOWARDS A PHYLOGENY OF THE DASYACEAE (CERAMIALES, RHODOPHYTA), BASED ON COMPARATIVE RBCL GENE-SEQUENCES AND MORPHOLOGY

Phylogenetic analyses of the Dasyaceae based on sequence analysis of t he large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (r bcL) and 42 morphological characters are presented. Comparative sequen ce analysis confirms the general view of the Ceramiaceae as a primitiv e, paraphyletic group giving rise to the Rhodomelaceae, Delesseriaceae and Dasyaceae within the monophyletic Ceramiales. On the basis of bot h data sets, the Heterosiphonia-like genera (Heierosiphonia, Colacodas ya and Dasyella) are the most primitive members of the Dasyaceae, wher eas the Dasya-like genera (Dasya, Pogonophorella, Eupogodon and Rhodop tilum) and Thuretia and Dictyurus are of more recent origin. On the ba sis of morphological data only, Thuretia and Dictyurus form a sister g roup to Heterosiphonia, and Eupogodon is monophyletic whereas Dasya an d Heierosiphonia are not. Primary radial symmetry has arisen once in t he Dasya clade but is secondarily obscured in some species by heavy, a symmetrical cortication that gives the appearance of bilateral symmetr y. This is illustrated by species of Eupogodon and Rhodoptilum.