The Allophaiomys complex in Southern Europe

Abstract

The representation of Allophaiomys in Southern Europe has increased considerably thanks to the intensive samplings carried out in recent years in the Guadix-Baza basin and other sites in Spain (Casablanca and Cueva Victoria fissure infillings). In addition to the type-species, Microtus (Allophaiomys) pliocaenicus, these finds have provided information on two additional species: M. (Allophaiomys) chalinei Alcalde, Agusti & Villalta and M. (Allophaiomys) vandermeuleni n. sp. (type-locality: Barranco de los Conejos in the Guadix-Baza basin, Southern Spain). The latter species differs from other Allophaiomys representatives by its large size and its very deep LRA-3 (lingual reentrant angle 3), which contrasts with the primitive shape of the anteroconid complex. The evolutionary relationships of the different Allophaiomys species are analyzed by two different approaches. First, the phenetic view of the early evolution of Microtus in Europe is based exclusively on the A, B and C parameters commonly used in the systematics of this genus. A second phylogenetic approach is attempted also taking into account other morphological characters. As a consequence of the results shown by the mostly parsimonious cladogram, the subdivision of the Allophaiomys stock into two assemblages, the first one dealing with the “European” Pitymys (or Terricola, according to Brunet-Lecomte, 1988) and a second one dealing with the Chionomys group, is proposed. Moreover, this divergence can be traced back to the very early Pleistocene, instead of the middle Pleistocene age usually accepted for this splitting process. Thus, M. (A.) vandermeuleni shares a common ancestor with the Chionomys group, while M. (A.) chalinei is situated close to the origin of M. (A.) nutiensis. On the other hand, M. (A.) burgondiae is proposed as the sisterspecies of M (Allophaiomys) jordanicus ( Haas) (not Arvicola). Therefore, a middle Pleistocene age is proposed for the site of Ubeidiya.