Four species of marine algae are reported from the Canary Islands for the first time. Our report of the western Atlantic Gelidiella setacea (Gelidiales, Rhodophyta) is the first from the eastern Atlantic Ocean. Pseudotetraspora marina (Tetrasporales, Chlorophyta) previously known on the eastern side of the Atlantic Ocean from temperate saltmarshes only, is now reported growing in the shallow sublittoral zone, the habitat in which tropical western Atlantic populations also occur. The presence of Lomentaria chylocladiella (Rhodymeniales, Rhodophyta) represents the first report in the Atlantic Ocean of a species previously thought to be endemic to the Mediterranean Sea. The record of the widely distributed Acrochaetium hallandicum (Acrochaetiales, Rhodophyta) was not unexpected. Specimens of A. hallandicum have vegetative cells with a single lobate parietal chloroplast with a single pyrenoid, a feature that among acrochaetioid algae occurs exclusively in the genus Colaconema (Colaconematales), and consequently the species is transferred to this genus. Fertile sporophytes are described for Gelidiella setacea, a species previously known only in its vegetative condition. Cruciately to irregularly divided sporangia are regularly arranged in transverse rows in stichidia laterally formed on the axes. The species is transferred to the genus Parviphycus on the basis of the morphology of the stichidia and the distichous pattern of apical division exhibited by the axes, both exclusive features of this genus.

Is a canopy-forming endemic macroalga from the Canary Islands. Vegetative and reproductive characteristics of all phases in its life cycle are examined. Key macromorphological features are its blackish color and the corymbose-to-subfastigiate branching pattern that differentiates

Sargassum species play a key role in habitat formation in tropical and subtropical regions; however, species identification has been hampered by the phenological plasticity exhibited in response to environmental conditions and life history. Molecular phylogenetics has challenged taxa circumscriptions and proven critical in delimiting species in this genus. Yet, the Atlantic species of Sargassum remain poorly understood, and recent studies have shown low molecular diversity between the species in the NW Atlantic. Here, we expand the taxon sampling to the NE Atlantic to assess the diversity of Sargassum in the Atlantic basin, based on a comprehensive morphological and multigene approach. We selected genes commonly used in delineating species in this genus (ITS2, rbcLS, cox3, mtsp) and explored additional markers (cox2, nad6, psbC, clpC, atpB) to infer the phylogenetic relationships between the morphospecies observed in the NE Atlantic. Phylogenetic analyses using single‐gene and multigene alignments including 185 new sequences confirmed the low molecular diversity and supported the distinction of a single clade in Sargassum section Sargassum of N Atlantic benthic species. In contrast, morphological analysis resulted in the identification of 10 species and three new morphospecies that we described here but opt not to equate to species until further molecular evidence is available. Our results were congruent with previous findings from the NW Atlantic and highlight the morphological and ecological diversity of Sargassum in the Atlantic. These results suggest a recent colonization and incipient speciation of Sargassum in the Atlantic basin and showcase the need of further high‐throughput analyses.

Cyanobacteria, known for their remarkable adaptability, are a diverse group of oxygenic photoautotrophic organisms found in various habitats worldwide. While their presence in aquatic ecosystems has been extensively studied, research on terrestrial and aerophytic cyanobacteria remains relatively limited, particularly concerning their taxonomic diversity and molecular characteristics. In this study, utilizing morphological and molecular data derived from the 16S rRNA gene, we unveiled and described two new species of filamentous cyanobacteria growing epiphytically on Laurus novocanariensis in the laurel forest (laurisilva) of the Canary Islands. The first species, Brasilonema novocanariensis sp. nov., belongs to a genus of aerophytic and subaerophytic nostocalean cyanobacteria. The second, Rhizonema melkonianarum sp. nov., belongs to the genus Rhizonema. The discovery of a new species of Brasilonema from the Canary Islands related to species initially found on the opposite side of the Atlantic Ocean, and recently in Asia, Europe, and Portugal, raises questions about their dispersal mechanisms, whether through natural means or human-mediated processes, prompting the need for future studies to investigate these propagation patterns. In the case of Rhizonema melkonianarum sp. nov., the transition from adapting to a basidiolichen host to inhabiting the phyllosphere of angiosperms raises ecological and evolutionary adaptation questions regarding cyanobacterial adaptability and their ecological roles in diverse habitats. This research expands our understanding of the diversity and geographic distribution of these terrestrial phyllosphere-associated cyanobacteria.