ANATOMICAL AND NUCLEAR SSU rDNA SEQUENCE DATA INDICATE THAT THE DASYACEAE AND DELESSERIACEAE ARE POLYPHYLETIC

Choi, H.‐G. 1,3 , Kraft, G. T. 2 , Lee, I. K. 3 & Saunders, G. W. 11 Centre for Environmental & Molecular Algal Research, Department of Biology, University of New Brunswick, Fredericton, N.B., E3B 6E1, Canada; 2 School of Botany, University of Melbourne, Parkville, Victoria 3010, Australia; 3 School of Biological Sciences, Seoul National University, Seoul 151‐742, Korea The aim of the current investigation was to test the general convention that the Dasyaceae, Delesseriaceae and Rhodomelaceae (Ceramiales, Rhodophyta) are all monophyletic. Phylogenetic relationships among 45 ceramialean taxa, including eight ceramiacean, 18 dasyacean, nine delesseriacean, eight rhodomelacean species and two of uncertain affiliation, based on 34 anatomical characters and nuclear small‐subunit (SSU) rDNA sequences were determined. Results from our ‘total‐evidence’ approach were consistent with the notion that the Dasyaceae, Delesseriaceae and Rho‐ domelaceae have evolved from a common ancestor within a paraphyletic Ceramiaceae. Our data indicate, however, that the Rhodomelaceae alone was monophyletic with the Dasyaceae unequivocally polyphyletic and the Delesseriaceae either polyphyletic, or paraphyletic in excluding the Dasya‐group. Based on our results the Heterosiphoniaceae fam. nov. H.‐G. Choi, Kraft, I.K. Lee et G.W. Saunders is proposed for the Heterosiphonia‐group, previously placed in the family Dasyaceae. Although the Dasyaceae sensu stricto is a natural group, it is in need of a thorough systematic investigation at the generic level. Our analyses indicate that the genus Dasya is polyphyletic in excluding Dasysiphonia, Eupogodon and Rhodoptilum, and Heterosiphonia japonica has affinities to this group as well.