Mattio Lydiane auteur aut IRD Payri Claude auteur aut IRD Stiger-Pouvreau V. auteur aut IRD text journalArticle eng text/pdf born digital access An assessment of Sargassum in French Polynesia was done through the critical revision of the literature, type specimens, and specimens from type localities. Sargassum samples were newly collected, and four morphotypes were identified on the basis of morphological characters. Molecular analysis of the nuclear ITS2, chloroplastic partial rbcLS, and mitochondrial cox3 markers generated two clades and confirmed the recent divergence suspected between closely related species. Although 18 different epithets have been attributed to French Polynesian Sargassum since 1828, only three species are considered valid in this study. Most of these species were transferred to S. pacificum Bory, the only species present in the Society Archipelago, while S. obtusifolium J. Agardh was restricted to the Austral Archipelago, and S. echinocarpum J. Agardh was confirmed for the Austral and Gambier Archipelagos. A morphological identification key is provided, along with descriptions and illustrations for each polymorphic species. Moreover, the study of several regional collections underlined similar and low specific diversity among Sargassum populations in the southeastern Pacific. As a result of this study, we propose that S. bacciferum J. Agardh var. latiuscula Grunow, S. bisserula f. pacifica Grunow, S. boraborense (Grunow) Setch., S. mangarevense (Grunow) Setch., S. sociale (Grunow) Setch., and S. tahitense Grunow be considered as heterotypic synonyms of S. pacificum. Sargassum skottsbergii Sjostedt, S. hawaiiensis Doty et Newhouse, S. divaricatum var. chilensis Grunow, S. obtusifolium J. Agardh f. chamberlainii Grunow, and S. obtusifolium J. Agardh f. lendigeroides Grunow are further regarded as heterotypic synonyms of S. obtusifolium. specialized biogeography cox3 French Polynesia ITS2 molecular phylogeny rbcLS Sargassum taxonomic revision 076 44 6 1541-1555 2008 0022-3646 https://www.documentation.ird.fr/hor/fdi:010044164 10.1111/j.1529-8817.2008.00597.x 0022-3646 [F B010044164] https://www.documentation.ird.fr/hor/fdi:010044164 https://www.documentation.ird.fr/intranet/publi/2009/01/010044164.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2009-02-06 2017-08-23 fdi:010044164 fre