Chronicle of an announced extinction: Microcondylaea bonellii, the species not worth saving?

Microcondylaea bonellii (Fig. 1) was recently used to exemplify the pathway that brings neglected species to extinction (Riccardi et al., 2021). It is a freshwater mussel that belongs to one of the least studied Unionidae subfamilies, the Gonideinae (Lopes-Lima et al., 2017). Species in this subfamily have suffered major declines, and almost half of the assessed Gonideinae species are currently listed as Near Threatened or Threatened (IUCN, 2021). This subfamily includes only three European species, Potomida acarnanica, P. littoralis and M. bonellii, all restricted to Southern Europe and all are poorly studied. Once populations extended from Switzerland to Greece with numerous populations, but currently M. bonellii is undergoing a strong and rapid decline all over its range. Declines or even disappearance of its populations caused the erosion of genetic diversity making it one of the European freshwater mussel species with the lowest genetic diversity (Froufe et al., 2017). The few remaining populations are so isolated that, in case of local extirpation, recolonization is unlikely.