Synopsis of the fossil freshwater crabs of Europe (Brachyura:Potamoidea: Potamidae)

摘要

The reappraisal of the European Neogene fossil freshwater crabs results in the recognitionof eight species, including one new species (Potamon hegauense n. sp.) of late Miocene age(c. 10.3 Ma) from Howenegg (southern Germany). All eight species are assigned to the genusPotamon (Potamidae). There is no morphological evidence for a closer relationship with Africanpotamonautids. The oldest known European freshwater crab is Potamon quenstedti from Engelswies(early Miocene, c. 17 Ma) in southern Germany. The last occurrence of potamids in Central Europeprior to the Pleistocene is recorded in the Vienna Basin (late Miocene, c. 8 Ma). In Italy (Tuscany)freshwater crabs (Potamon castellinense) are documented well before (c. 5.5 Ma) the presumedpostglacial invasion of extant Potamon fluviatile. The latest Pliocene-Pleistocene species Potamonantiquum from northern Hungary probably represents extinct populations of Potamon ibericum at thenorthern limit of its range. The scarce records and the lack of dating of the southwest Asian Potamonsivalense hampers considerations about origin, dispersal events and palaeobiogeography of potamidsin Europe up to now. However, a slow southward withdrawal of freshwater crabs, induced by climatecooling at the end of the Miocene, is marked by the extinction of P hegauense in the circum-Alpinerealm, P antiquum in Hungary, and probably P castellinense in Italy.