New data on the biodiversity of Solenogastres (Mollusca, Aplacophora) in the Mediterranean Sea: findings from the program “Our Planet Reviewed” Corsica 2019-2022

The discovery and description of new species of Solenogastres (Mollusca, Aplacophora) is still routine, even from relatively well-known regions, but less effort is focused on the redescription of known species. Phylogenetic studies have shown that significant revisionary systematic work is needed in this group and enhanced morphological descriptions and molecular data will be valuable in these pursuits. Additionally, advancing knowledge on the real distribution and diversity of these molluscs adds to an increased understanding of marine biodiversity in general. Here, we present the study of 47 solenogasters collected during the “Our Planet Reviewed” expedition to Corsica (Mediterranean Sea). Following an integrative taxonomic approach (considering observations of live animals, habitat, morphology, and DNA barcoding), we identified ten species across seven different families: Dondersiidae Simroth, 1893; Lepidomeniidae Pruvot, 1902; Pruvotinidae Heath, 1911; Rhopalomeniidae Salvini-Plawen, 1978; Simrothiellidae Pilsbry, 1898; Proneomeniidae Simroth, 1893 and Strophomeniidae Salvini-Plawen, 1978. Notably, these findings constitute the first documented records of solenogasters off Corsica. In light of the studied material, the synonymy of three Pruvotinidae species (Eleutheromenia sierra (Pruvot, 1890), E. carinata Salvini-Plawen & Öztürk, 2006, and Gephyroherpia impar Zamarro, García-Álvarez & Urgorri, 2013) is proposed. This taxonomic clarification highlights the need for more study of Pruvotinidae. Further, the value of live observations (very rare in solenogasters) for better description of species and their importance for species identification is emphasized in this work. Taken together, the outcomes of our investigation demonstrate the value of species redescriptions, underscore the necessity for revisionary systematics and taxonomy of Solenogastres, and address a gap in our understanding of their diversity in the Mediterranean Sea with the first documentation of the group in Corsican waters.