The fan mussel Pinna nobilis represents the largest bivalve endemic to the Mediterranean Sea and is affected since 2016 by a widespread mortality. The first surveys suggested that Haplosporidium pinnae was the main etiological agent.

This study performed molecular analyses to shed further light on the pathogens involved in the mass mortality.

The results support the occurrence of a multifactorial disease and that Mycobacterium spp. and H. pinnae are not necessarily associated with the illness. The study also found the species Rhodococcus erythropolis, representing the first report in fan mussels of a bacterium other than Mycobacterium spp. and Vibrio spp.

The authors conclude that these results depict a complicated scenario, further demonstrating how the P. nobilis mass mortality event is far from being fully understood.

Scarpa et al. (2020) Multiple non-species-specific pathogens possibly triggered the mass mortality in Pinna nobilis. Life 10: 238.