Biogeographia – The Journal of Integrative Biogeography

We present here a first comprehensive database on the diversity of proseriate flatworms (Platyhelminthes: Rhabditophora: Proseriata) on Western Mediterranean microtidal, wave dominated beaches. We sampled 116 stations in two years, through Spain (22 beaches, including Balearic Islands), France (25 beaches, including Corsica), Italy (63 beaches, including Sardinia, Sicily, and Lampedusa), and Tunisia (6 beaches). In each beach, we sampled at three depths, corresponding to the swash, shoal, and subtidal zones. For each sample, we obtained environmental data. The research yielded a total of 152 species, of which 93 were new to science. For each of the species found, we coded and described 16 functional traits. We discuss the functional meaning of the selected traits, as well as on diversity patterns and emerging biogeographic signals across the investigated regions. We particularly focused on the most widespread and dominant species in our dataset, concentrating on their putative adaptations to high energy environments; as well as the high number (58) of the species only found once. Finally, we discussed the coverage of our sampling by estimating the diversity at each investigated region and comparing it to the actual diversity. All information provided is available through the Global Biodiversity Information Facility (GBIF) and the Open Science Framework (OSF) following the Darwin Core Standard.