Ancipitecancer collinsi, a new genus and species of problematic eubrachyuran crab from the Pleistocene of Italy

Abstract

A new genus and species of eubrachyuran crab, Ancipitecancer collinsi, are recorded from lower Pleistocene strata exposed in the Poggi Gialli quarry (Sinalunga, Tuscany, central Italy). This new form is unlike any fossil or extant crab species known to us. The overall carapace shape and dorsal configuration of Ancipitecancer nov. gen. fit the Eubrachyura well, and among eubrachyurans we assign it tentatively to the Xanthoidea sensu lato. Although xanthoid-like crabs are amongst the most anatomically diverse groups of true crabs, the unusual body of Ancipitecancer nov. gen. cannot be accommodated within any brachyuran family currently recognised.