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Phylogenetic analyses of anatomical and nuclear SSU rDNA sequence data indicate that the Dasyaceae and Delesseriaceae (Ceramiales, Rhodophyta) are polyphyletic

Published online by Cambridge University Press:  18 December 2002

HAN-GU CHOI
Affiliation:
Institute for Natural Sciences, Kangnung National University, Kangnung 210-702, Republic of Korea
GERALD T. KRAFT
Affiliation:
School of Botany, University of Melbourne, Parkville, Victoria 3052, Australia
IN KYU LEE
Affiliation:
School of Biological Sciences, Seoul National University, Seoul 151-742, Korea
GARY W. SAUNDERS
Affiliation:
Centre for Environmental & Molecular Algal Research, Department of Biology, University of New Brunswick, Fredericton, N.B., E3B 6E1, Canada
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Abstract

The aim of the current investigation was to test the general convention that the Dasyaceae, Delesseriaceae and Rhodomelaceae are all monophyletic families of the red algal order Ceramiales. Phylogenetic relationships among 45 ceramialean taxa were determined, including eight ceramiacean, 18 dasyacean, nine delesseriacean and eight rhodomelacean species, plus two of uncertain ceramialean affinities, based on 34 anatomical characters and nuclear small subunit (SSU) rDNA sequences. Results from our ‘total-evidence’ approach were consistent with the notion that the Dasyaceae, Delesseriaceae and Rhodomelaceae have evolved from a common ancestor within a paraphyletic Ceramiaceae. Our data indicate, however, that the Rhodomelaceae alone is monophyletic at the family level, with both the Dasyaceae and Delesseriaceae polyphyletic. In particular we resolved two independent and well-supported lineages for the included Dasyaceae, viz., a Dasya group and a Heterosiphonia group, which were as distinct from one another as they were from the Rhodomelaceae and the various lineages of Delesseriaceae. The molecular data alone were equivocal on the issue of monophyly of the Dasyaceae. We therefore advocate conservative taxonomic revisions as an interim step towards eventual resolution of familial-level taxonomy in the Ceramiales. Based on our results, the Heterosiphonioideae H.-G. Choi, Kraft, I.K. Lee et G.W. Saunders subfam. nov. is proposed for Heterosiphonia and five closely related genera, and the Dasyoideae Schmitz et Falkenberg is emended for the remaining taxa. Although the Dasyoideae is a natural group, it is in need of a thorough systematic reinvestigation at the generic level. Our analyses indicate that the genus Dasya is polyphyletic or paraphyletic in excluding Dasysiphonia, Eupogodon and Rhodoptilum and that Heterosiphonia japonica also has affinities to this group, taxonomic issues that will be addressed in detail elsewhere.

Type
Research Article
Copyright
© 2002 British Phycological Society

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