The fan mussel Pinna nobilis is an endemic bivalve of the Mediterranean Sea, protected by international legislation as an endangered species. This species is being widely affected by a mass mortality event that started in the coasts of Spain in 2017.

This study assessed the presence of potential pathogens in moribund P. nobilis individuals from the Gulf of Taranto (Ionian Sea), where a mass mortality event was detected in the early summer of 2018.

The results of the histological and molecular analyses showed the presence of Haplosporidium pinnae in the analysed fan mussels.

The authors thus conclude that H. pinnae was the causative agent of the mass mortality in the populations of P. nobilis sampled in the Ionian Sea, where the conservation of this endangered species is heavily threatened by such a protozoan infection.

https://www.sciencedirect.com/science/article/pii/S0022201118303641

Panarese et al. (2019) Haplosporidium pinnae associated with mass mortality in endangered Pinna nobilis (Linnaeus 1758) fan mussels. Journal of Invertebrate Pathology 164:32-37.