A new giant cricetine from the basal Pliocene of Mallorca (Balearic Islands, western Mediterranean): biostratigraphic nexus with continental mammal zones

A new insular giant species of Apocricetus (M1 length > 4.22 mm, upper teeth row length > 10.90 mm) is described from dental, mandibular and cranial material recovered at the Na Burguesa-1 site (Mallorca, Balearic Islands, western Mediterranean), a Zanclean palaeokarst deposit chronologically close to the refilling of the Mediterranean after the Messinian Salinity Crisis. Apocricetus darderi sp. nov. shows a close relationship with the mainland species A. alberti (MN13), an Iberian taxon, from which it differs in size, the presence of labial and lingual anterolophids in m1, triple anterolophulids frequently developed, a reduced anterosinusid in m2 and m3 and, occasionally, the presence of an ectomesolophid in m3. Apocricetus darderi sp. nov. becomes the first endemic Balearic mammal that can be confidently assigned as having a direct mainland relative, providing the first solid palaeontological evidence of a Messinian origin for the Plio-Pleistocene fauna of Mallorca. Tragomys macpheei from the Caló den Rafelino site (Early Pliocene, probably late MN14 or early MN15) displays a peculiar selenodont teeth pattern and a high degree of hypsodonty, and is considered to be either a direct descendant of Apocricetus darderi sp. nov. or a sister taxon derived from a common ancestor. http://www.zoobank.org/urn:lsid:zoobank.org:pub:0EBF0B6E-2922-4A14-A6C3-8FC8D751647F.This paper is a contribution funded by the Agencia Estatal de Investigación (Ministerio de Economía, Industria y Competitividad)/Fondo Europeo de Desarrollo Regional (FEDER) to the Research Projects [CGL2012-38089], [CGL2016-79795-R] and [CGL2016-80000-P]; funded by the Generalitat de Catalunya [SCR-901]. One of authors (ETR) benefited from a Predoctoral fellowship of the Spanish Ministerio de Economía, Industria y Competitividad [BES-2013-062867] during the course of this study