A freshwater turtle from the lithographic limestone of Las Hoyas (Barremian of Cuenca, Spain) is described as a new genus and species of Eucryptodira, Hoyasemys jimenezi. The holotype consists of the skull, lower jaw, carapace, plastron, vertebral column, pectoral and pelvic girdle remains, and fore− and hindlimbs. Hoyasemys jimenezi gen. et sp. nov. is characterized by three pairs of blind oblique depressions on the ventral surface of the basisphenoid, and a character combination composed, among others, of the articulation between the fourth and fifth cervical vertebrae through a cotyle in the fourth and a condyle in the fifth, amphicoelous caudal centra, and most digits of manus and pes with three elongated phalanges. This study allows clarification of the systematic position of a species of uncertain affinity often identified as “chelydroid” in appearance. A phylogenetic analysis shows Hoyasemys jimenezi gen. et sp. nov. forms a monophyletic group with Judithemys sukhanovi, Dracochelys bicuspis, Sinemys lens, and Ordosemys leios, collectively the sister groupof crown Cryptodira.

Key words: Testudines, Eucryptodira, freshwater turtle, Barremian, Cretaceous, Las Hoyas, Spain.

Adán Pérez-García [paleontologo@gmail.com], Departamento de Paleontología, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, José Antonio Novais 2, 28040 Ciudad Universitaria, Madrid, Spain; Marcelo S. de la Fuente [mdelafu@gmail.com], Departamento de Paleontología, Museo de Historia Natural de San Rafael, Parque Mariano Moreno S/Nº (5600), San Rafael, Provincia de Mendoza, Argentina; Francisco Ortega [fortega@ccia.uned.es], Grupo de Biología, Facultad de Ciencias, UNED, Senda del Rey 9, 28040 Madrid, Spain.