A revision of the genus Europicardium Popov, 1977 (Bivalvia: Cardiidae) from the European Neogene: tracking palaeogeography and climate changes

The cardiid genus Europicardium Popov, 1977 was introduced for a small group of Cenozoic species from Europe, but remained almost unknown in the western literature until about 15 years ago, and its type species, Cardium multicostatum Brocchi, 1814, continued to be cited mainly as Trachycardium multicostatum. Many records are available for this species from the Miocene of Europe, but most are based on several distinct, often misidentified species. In the present revision, based on museum material, the taxonomy of Europicardium is discussed and the identity of its type species is fixed. Seven species are assigned to Europicardium: E. multicostatum (Brocchi, 1814), E. miorotundatum (Sacco, 1899) (lectotype designated), E. miocaudatum (Sacco, 1899), E. polycolpatum (Cossmann & Peyrot, 1912), E. pseudomulticostatum (Zhizhchenko, 1934), E. badeniense (Kokay, 1996) and E. hoernesi sp. nov. from the middle Miocene of Austria. However, literature records and museum material suggest the occurrence of additional species and the need for further investigation. The oldest record of Europicardium is from the early Miocene of the Aquitaine Basin, from where the genus likely spread into the Mediterranean and throughout the Paratethys. Europicardium reached a maximum diversity in the early middle Miocene (Badenian) of the Paratethys, probably in relation to the Miocene Climatic Optimum, and also with the complex and variable palaeogeography of the Paratethys, which promoted differentiation and diversity. Europicardium disappeared from the Paratethys when it became a freshwater basin in the late Miocene, and from the Mediterranean due to the Messinian Salinity Crisis. The last European species was E. multicostatum, which arrived in the Mediterranean from the adjacent Atlantic with the post-Messinian recolonization, and became extinct in the Pleistocene due to climatic deterioration. At the present day, Europicardium occurs in the tropical waters of West Africa, with three species