Contribution to the knowledge of freshwater red algae: the genus Thorea in the Canary Islands

Abstract

The genus Thorea Bory (Rhodophyta) has long posed taxonomic challenges due to the morphological similarities among other genera and the infrequent observation of sexual reproductive structures in freshwater environments. However, recent advancements in analysing life cycles, and molecular data have enabled a more accurate reclassification of morphologically alike genera. Despite its global distribution, the diversity of Thorea in the Macaronesia region, including the Canary Islands, has been largely underexplored, leading to historical misidentifications. To address this gap, a recent study focused on the freshwater macroalgal diversity of Gran Canaria. This research involved cultivating specimens collected from hot springs in the Guayadeque ravine under controlled conditions, allowing for the observation of various life cycle phases. Additionally, detailed morphological analyses were combined with molecular comparisons against all known freshwater species of the genus. The findings confirm the first recorded presence of Thorea in the Canary Islands, underscoring the critical need for continued exploration of freshwater biodiversity within the Macaronesia region. This discovery highlights the indispensable role of integrating morphological and molecular studies for precise classification and a deeper understanding of algal diversity in under-researched areas.