The first castorid remains from the area of els Hostalets de Pierola (l'Anoia, Catalonia, Spain), in the Vallès-Penedès Basin, are described in this article. These fossil remains from Abocador de Can Mata (ACM), including a nearly complete hemimandible, two maxillary fragments, and several isolated teeth from locality C4-C2 (Late Aragonian, MN7 8), as well as an almost complete femur from the similarly-aged locality C3-Ak, are attributed to the genus Chalicomys (=Palaeomys). Taxonomic and nomenclatural issues regarding this genus are discussed. An emended diagnosis of this genus is provided, and a new species, Chalicomys batalleri sp. nov., is described on the basis of the ACM/C4-C2 specimens. The femur from ACM/C3-Ak is also tentatively included within the hypodigm of the newly erected species. Paleobiological inferences on the locomotor repertoire of Chalicomys are made on the basis of femoral anatomy. It is concluded that, like living Castor, these extinct beavers were efficient swimmers, highly committed to aquatic locomotion, which propelled mainly by means of hind feet paddling. The presence of an extinct beaver with Castor-like aquatic adaptations in this area, together with the sedimentological evidence, suggests more humid conditions than previously thought, at least for a restricted to a short time interval, given the rarity of castorid remains elsewhere in the ACM stratigraphic series.