The genus Stephanomys (Muridae, Rodentia) is one of the most common elements in the late Miocene to Early Pleistocene mammal faunas from the Ibero-Occitan region. Its geographic distribution is limited to this area with only two mentions in the late Miocene of Italy (de Giuli, 1989) and Algeria (Coiffait et al., 1985). The genus has been subject of numerous studies, some of them suggesting different interpretations on the phylogenetic relationships between the various described species (Gmelig-Meyling and Michaux, 1973; Cordy, 1978; Adrover, 1986; Bachelet and Castillo-Ruiz, 1990; Aguilar et al., 1993). The most extensive and significant study of the genus is the Ph.D. dissertation of Cordy (1976), who studied in detail several samples of Stephanomys, analyzed the changes observed in successive populations and defined four species (S. medius, S. michauxi, S. thaleri and S. progressus), which are considered as nomina nuda because this work was never published. Only one of these species, S. thaleri from the French locality of Seynes, was validated later by López-Martinez et al. (1998).