Freshwater Molluscs of Morocco: An Updated Checklist, Biodiversity Hotspots, and Conservation Issues

Abstract

This study provides the first updated checklist of Moroccan freshwater molluscs, synthesizing faunistic knowledge accumulated between 1795 and 2026. The dataset was primarily compiled from specialized literature, complemented by the authors’ expertise and recent field investigations. Taxonomic classifications at the family, genus, and species levels were revised in accordance with current systematic interpretations. In total, 106 freshwater molluscan species, belonging to 55 genera and 14 families, were documented. Chorological analysis reveals a clear dominance of Palearctic elements, particularly of Mediterranean affinity, alongside a high proportion of strictly endemic Moroccan taxa. Most of these endemics are associated with springs (crenobionts) and subterranean habitats (stygobionts), emphasizing the role of these environments as key centres of micro-endemism and diversification. A comprehensive database comprising 838 occurrence records was assembled, including GPS coordinates and sampling dates. The analysis identifies biodiversity hotspots mainly concentrated in the Mediterranean part of Morocco, particularly within the Middle Atlas Mountains, followed by the northeastern regions, where the highest species richness and citation rates were recorded. Despite this progress, significant gaps remain in the knowledge of Moroccan freshwater molluscs. Several regions still require further exploration, while ongoing threats—including pollution, habitat degradation driven by anthropogenic activities, global environmental change, and biological invasions—pose significant challenges. Addressing these gaps calls for intensified research efforts, including comprehensive field surveys, integrative taxonomic and molecular approaches, and long-term ecological monitoring. Overall, this study represents a significant step toward advancing the knowledge and conservation of freshwater molluscan diversity in Morocco.