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In 2015 a new exotic seaweed with invasive behaviour was detected at the Strait of Gibraltar (western Mediterranean), which was morphological and genetically identified as Rugulopteryx okamurae. Due to its rapid expansion and remarkable ecological, economic, and social impacts, the species was included in the Spanish Checklist of exotic invasive species. However, distribution models of the species identified other European coasts as favourable for this new invader. In this presentation we provide scientific arguments for the inclusion of R. okamurae in the list of invasive species of European Union concern, becoming the first seaweed species to be included in that list. Fundación Biodiversidad-Miteco. Universidad de Málaga (Plan propio de investigación). Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

The molecular phylogeny of brown algae was examined using concatenated DNA sequences of seven chloroplast and mitochondrial genes (atpB, psaA, psaB, psbA, psbC, rbcL, and cox1). The study was carried out mostly from unialgal cultures; we included Phaeostrophion irregulare and Platysiphon glacialis because their ordinal taxonomic positions were unclear. Overall, the molecular phylogeny agreed with previously published studies, however, Platysiphon clustered with Halosiphon and Stschapovia and was paraphyletic with the Tilopteridales. Platysiphon resembled Stschapovia in showing remarkable morphological changes between young and mature thalli. Platysiphon, Halosiphon and Stschapovia also shared parenchymatous, terete, erect thalli with assimilatory filaments in whorls or on the distal end. Based on these results, we proposed a new order Stschapoviales and a new family Platysiphonaceae. We proposed to include Phaeostrophion in the Sphacelariales, and we emended the order to include this foliose member. Finally, using basal taxa not included in earlier studies, the origin and divergence times for brown algae were re‐investigated. Results showed that the Phaeophyceae branched from Schizocladiophyceae ~260 Ma during the Permian Period. The early diverging brown algae had isomorphic life histories, whereas the derived taxa with heteromorphic life histories evolved 155–110 Ma when they branched from the basal taxa. Based on these results, we propose that the development of heteromorphic life histories and their success in the temperate and cold‐water regions was induced by the development of the remarkable seasonality caused by the breakup of Pangaea. Most brown algal orders had diverged by roughly 60 Ma, around the last mass extinction event during the Cretaceous Period, and therefore a drastic climate change might have triggered the divergence of brown algae.

International audience; Based on morphological characters, cross-fertility and molecular systematics, two species are currently recognized in the ubiquitous temperate brown algal genus Ectocarpus: the type species E. siliculosus (Dillwyn) Lyngbye and E. fasciculatus Harvey. We studied diversity , cross-fertility and ecology of Ectocarpus in mega-tidal areas in northwest France (Western Europe) and propose to reinstate a third species, E. crouaniorum Thuret in Le Jolis. Genotyping of 67 individuals from five localities, including the type locality of E. crouan-iorum, using internal transcribed spacer 1 (ITS1) length as a marker, showed that the three species co-occurred whenever the habitat was suitable. Our survey also revealed a single putative field hybrid between E. crouaniorum and E. siliculosus, and a single individual of a further Ectocarpus genotype. In laboratory experiments, E. crouaniorum was crossed with E. siliculosus and E. fasciculatus. In 12 of 13 crosses, the zygotes did not develop (postzygotic sterility); in one experiment a viable hybrid was produced after crossing a female E. crouaniorum with a male E. siliculosus, but this hybrid was unable to form meiospores. Phyloge-netic analysis of five molecular markers from the nuclear, mitochondrial and plastid genomes (in total 1818 bp) confirmed genetic separation of the three species. Ecologically, E. crouaniorum was confined to high intertidal pools and runoffs , where the gameto-phyte was common from spring to summer. Another characteristic was that it usually occurred as an epi-phyte of up to 12 cm in length on erect thalli of Scy-tosiphon lomentaria. Sporophytes of E. crouaniorum were found all year long; they were