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DNA SEQUENCE DATA DEMONSTRATE THE POLYPHYLY OF THE GENUS CYSTOSEIRA AND OTHER SARGASSACEAE GENERA (PHAEOPHYCEAE)1 |
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| Authors: | Stefano G. A. Draisma Enric Ballesteros Florence Rousseau Thierry Thibaut |
| Affiliation: | 1. Institute of Ocean and Earth Sciences, University of Malaya, Kuala Lumpur 50603, Malaysia Netherlands Centre for Biodiversity Naturalis (section NHN), Leiden University, P.O. Box 9514, 2300 RA, Leiden, the Netherlands;2. Author for correspondence: e‐mail .;3. Centre d’Estudis Avan?ats de Blanes‐CSIC, Acc. Cala Sant Francesc 14, 17300, Blanes, Spain;4. UMR 7138 “Systématique, Adaptation Evolution” (UPMC, MNHN, CNRS, IRD) case postale N° 39, 57, rue Cuvier, 75231 Cedex 05 Paris, France;5. Université de Nice‐Sophia Antipolis – EA ECOMERS 4228 – Parc Valrose – 06108 Nice Cedex 02, France |
| Abstract: | Phylogenetic relationships in the Sargassaceae were explored using three DNA markers, and the monophyly of its genera was challenged. Nineteen out of 24 currently recognized genera were sampled, representing 63 species. The variable mt23S‐tRNA Val intergenic spacer could only be aligned within genera and could not be used to infer intergeneric relationships. The partial mt23S was also useful to delineate genera and was alignable at the family level but provided few informative characters. Analysis of mt23S DNA sequences together with chloroplast‐encoded psbA sequences resulted in a better resolved phylogeny. Hormophysa was the first genus to branch off within the Sargassaceae, followed by Myriodesma; then the three genera Caulocystis, Carpoglossum, and Scaberia in unresolved order; and then Acrocarpia. The other taxa studied here were divided over three major clades, but there was no branch support for the monophyly of two of these. The genera Bifurcaria, Cystoseira, Halidrys, and Sargassum appeared polyphyletic. The following taxonomic changes are proposed: a new genus Brassicophycus for Bifurcaria brassicaeformis (Kützing) E. S. Barton; reinstatement of the genus Sargassopsis for Sargassum decurrens (R. Brown ex Turner) C. Agardh; reinstatement of the genus Sirophysalis for Indo‐Pacific Cystoseira trinodis (Forsskål) C. Agardh; reinstatement of the genus Polycladia for the western Indian Ocean species Cystoseira indica (Thivy et Doshi) Mairh, Cystoseira myrica (S. G. Gmelin) C. Agardh, and Acystis heinii Schiffner; and reinstatement of the genus Stephanocystis for the North Pacific Cystoseira species and Halidrys dioica N. L. Gardner. The European Cystoseira species should be split into three genera, but no name changes are proposed yet, because diagnostic characters were found only for the clade including the type species. Some evolutionary trends could be discerned from the mt23S + psbA phylogeny. |
| Keywords: | Bifurcaria Brassicophycus Cystoseira mitochondrial 23S phylogeny Polycladia psb A Sargassopsis Sirophysalis Stephanocystis |