Free-living clinging flatworms (Rhabditophora, Polycladida) associated with Sargassum from the Caribbean Coast of Colombia

This study documents, for the first time, the occurrence of <i>Gnesiocerossargassicola</i> and <i>Chatziplanagrubei</i> in <i>Sargassum</i> along the Caribbean coast of Colombia. High-definition photographs of whole mounts and histological sections are provided for both species, along with detailed observations of their reproductive structures and 28S rDNA barcodes. These findings underscore the importance of exploring the fauna associated with <i>Sargassum</i>, contributing to a better understanding of polyclad distribution and raising the number of recorded species for Colombia to 26.