Species of Hispanomys from the late Aragonian and early Vallesian (middle-late Miocene) of the Calatayud–Daroca Basin, Zaragoza, Spain

Abstract

The cricetid genus Hispanomys has been recorded from many localities in the Iberian Peninsula, France, and central and western Europe; its stratigraphic distribution is restricted to the middle Miocene and the beginning of the late Miocene. Four species are found in the Spanish Calatayud–Daroca Basin: Hispanomys aguirrei (local biozone G3, late Aragonian), H. lavocati (local biozone G3, late Aragonian), H. nombrevillae (local biozone H, late Aragonian-early Vallesian) and H. aragonensis (local biozone I, early Vallesian). New morphological analyses of these species are presented here resulting in the emended diagnoses and new differential diagnoses of H. nombrevillae and H. aragonensis. Morphologically, these species can be clustered in two groups: Hispanomys aguirrei and H. lavocati, which display characters typical of a basal Hispanomys, and H. nombrevillae and H. aragonensis that have a homogeneous morphology and their characters are more derived than the former group. Hispanomys aragonensis is the most derived species studied herein. Both groups of species were originated in southwestern Europe and are endemic of the Iberian Peninsula, although they do not seem to be phylogenetically related. A trend towards size decreasing in time is observed within the genus, Hispanomys aguirrei and H. lavocati being older and larger than H. nombrevillae and H. aragonensis.