Insights into the species diversity of the genus Sargassum (Phaeophyceae) in the Mediterranean Sea, with a focus on a previously unnoticed taxon from Algeria

Nine species of the genus Sargassum (Phaeophyceae; kingdom Stramenopiles) are currently accepted in the Mediterranean Sea: S. acinarium, S. desfontainesii, S. flavifolium, S. furcatum, S. hornschuchii, S. muticum, S. ramentaceum, S. trichocarpum and S. vulgare. Sargassum desfontainesii and S. furcatum are Atlantico-Mediterranean species. Sargassum hornschuchii, S. ramentaceum and S. trichocarpum are endemic to the Mediterranean. The presence of the Atlantic S. flavifolium in the Mediterranean is at least in part based upon a misidentification and therefore requires confirmation. Near Algiers and Annaba (Algeria), a Sargassum taxon sharing most characters with S. flavifolium was collected. This taxon, referred to as the Algerian Sargassum sp., is described and illustrated. Its distribution and ecology in Algeria are presented. This taxon differs from S. flavifolium in having costate, small-sized, unbranched leaves and small-sized receptacles, branched in all directions and lacking a branched sterile pedicel at the base. In the absence of genetic data, and a study of the type material of S. flavifolium, syntype localities: West Indies (Antilles) and Biarritz, a description of a new taxon would be premature.