Pseudunio marocanus

Pseudunio marocanus, the Moroccan freshwater pearl mussel, is a critically endangered (CR) bivalve mollusc endemic to a small number of river systems in Morocco, primarily in the Rif and Middle Atlas regions. This species belongs to the family Margaritiferidae, a group of long-lived freshwater mussels known for their ecological role as natural water filters and their sensitivity to changes in water quality. Individuals possess an elongated, dark brown to black shell, often eroded or discoloured with age, and the species is thought to be capable of considerable longevity, as is typical for its family.

Pseudunio marocanus inhabits clear, well-oxygenated streams and rivers with stable substrates, where it burrows partially into gravel or sand and relies on host fish species to complete its larval (glochidia) development, a life-history trait shared with related pearl mussels. The species is restricted to a highly fragmented range, with surviving populations known from only a handful of watercourses, making it exceptionally vulnerable to localized disturbances. Population trends are decreasing, driven by cumulative pressures on Morocco's freshwater systems.

Conservation attention has grown in recent years, with researchers highlighting the species as a priority for freshwater biodiversity assessments in North Africa, and some of its known localities fall within or near areas identified for potential protective management. A cautiously encouraging development is that recent taxonomic and distributional surveys have improved scientific understanding of the species' range and biology, providing a stronger foundation for targeted conservation planning going forward. Continued monitoring of remaining populations, combined with water resource management in the region, offers a realistic pathway to stabilizing this critically endangered species if implemented promptly.

This freshwater mussel inhabits clean, flowing rivers and streams in the Atlas Mountains and coastal watersheds of Morocco. It requires well-oxygenated waters with stable substrates of sand, gravel, or rocky bottoms where it can filter-feed and complete its complex life cycle.