PHYLOGENY OF THE DUMONTIACEAE (GIGARTINALES, RHODOPHYTA) AND ASSOCIATED FAMILIES BASED ON SSU rDNA AND INTERNAL TRANSCRIBED SPACER SEQUENCE DATA |
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Authors: | Vera Tai Sandra C Lindstrom Gary W Saunders |
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Institution: | Department of Biology, University of New Brunswick, Fredericton, NB, Canada E3B 6E1;Department of Botany, #3529-6270 University Boulevard, University of British Columbia, Vancouver, BC, Canada V6T 1Z4;Department of Biology, University of New Brunswick, Fredericton, NB, Canada E3B 6E1 |
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Abstract: | Small subunit (SSU) rDNA was sequenced for 25 species in 19 genera of the Gigartinales (Rhodophyta). As well, the internal transcribed spacer (ITS) region was sequenced, and a data matrix of 36 morphological characters was constructed for 16 species of Dumontiaceae. Phylogenetic trees were calculated from a multiple alignment of the SSU sequence data to infer relationships between species of Dumontiaceae and other gigartinalean taxa. The SSU analysis produced a polyphyletic Dumontiaceae. Notably, Acrosymphyton failed to associate with the included Gigartinales, let alone the Dumontiaceae, supporting an earlier proposal to remove it to a new family. The analyses were equivocal about the phylogenetic affinities of Dudresnaya , which clustered with the Kallymeniaceae, and the affinities of the Indo-West Pacific Gibsmithia , Kraftia , and Dasyphloea , the last-mentioned clustering with the Antarctic Gainiaceae, and these four taxa with Portieria (Rhizophyllidaceae). Further investigations are necessary to resolve relationships among these taxa. Rhodopeltis , a genus recently moved to the Dumontiaceae from the Polyideaceae, showed a weak association with the remaining northern Dumontiaceae. The final group consisted of cold-temperate Northern Hemisphere species. Phylogenetic analyses using a combination of SSU, ITS, and morphological data within this clade produced two strongly supported clades, a Dilsea / Neodilsea clade and a Cryptosiphonia / Dumontia clade. Dilsea is derived from a paraphyletic Neodilsea and may itself be polyphyletic. Atlantic and Pacific isolates of Dumontia contorta clearly showed sufficient divergence to warrant recognition as distinct species, and Dumontia alaskana , sp. nov. is proposed for the Pacific species. |
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Keywords: | Acrosymphyton Dumontia alaskana Dumontia contorta Dumontiaceae Gainiaceae Gigartinales molecular systematics phylogeny Rhodopeltis |
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