Quercomys bijmai gen. nov. sp. nov., a new dormouse of the subfamily Myomiminae, is described from the Oligocene/Miocene Boundary Interval of Santa Cilia (Huesca), Quel-1 and Fuenmayor-2 (La Rioja). Quercomys gen. nov. is characterized by its medium size, its hypsodont teeth, and its simple dental pattero. It is related to other genera, like Praearmantomys, Armantomys or Pseudodryomys , and its appearance is at a moment of high diversity of the family.