New species of Rotundomys (Cricetinae) from the Late Miocene of Spain and its bearing on the phylogeny of Cricetulodon and Rotundomys.

Raquel López-Antoñanzas,Ángeles Álvarez-Sierra,Pablo Peláez-Campomanes

doi:10.1371/journal.pone.0112704

Abstract

The material of Rotundomys (Rodentia, Cricetinae) from the Late Miocene fossiliferous complex of Cerro de los Batallones (Madrid, Spain) is described and compared with all species currently placed in the genera Rotundomys and Cricetulodon. Both the morphology and size variation encompassed in the collection of specimens from Batallones suggest they belong to a single taxon different from the other known species of these genera. A new species Rotundomys intimus sp. nov. is, therefore, named for it. A cladistic analysis, which is the first ever published concernig these taxa, has been conducted to clear up the phylogenetic position of the new species. Our results suggest that Rotundomys intimus sp. nov. inserts between R. mundi and R. sabatieri as a relatively primitive taxon inside the clade Rotundomys. The new taxon is more derived than R. mundi in having a transversal connection between the metalophulid and the anterolophulid on some m1 but more primitive than R. sabatieri and the most evolved species of Rotundomys (R. montisrotuni +R.bressanus) in its less developed lophodonty showing distinct cusps, shallower valleys, and the presence of a subdivided anteroloph on the M1. The species of Cricetulodon do not form a monophyletic group. As a member of Rotundomys, Rotundomys intimus sp. nov. is more derived than all of these taxa in its greater lophodonty and the complete loss of the anterior protolophule, mesolophs, and mesolophids.

Highlights

The Cerro de los Batallones fossiliferous complex (CBFC) comprises a set of nine sites that have yielded vertebrate remains of Late Miocene age
[18] Rotundomys intimus sp. nov. urn: lsid: zoobank.org: act: 9BA54135-D98E-4047-88EF-7494ACA713CF (Figures 3, 4, 5, 6, 7) Etymology: From the Latin intimus, the most interior, in reference to the fact that the locus typicus is situated in the innermost position with respect to the other Spanish sites, which are much closer to the shore
The general morphological pattern of Rotundomys intimus sp. nov. recalls that of R. montisrotundi and R. sabatieri

Summary

Introduction

The Cerro de los Batallones fossiliferous complex (CBFC) comprises a set of nine sites that have yielded vertebrate remains of Late Miocene age. It is situated in Torrejon de Velasco, South of the city of Madrid (Spain) (Figure 1). Amphibians, reptiles, and birds, the sites of Cerro de los Batallones deserve the attention they have received because of both the abundance and pristine conservation of the fossil carnivores and herbivores they yield [2]. Rotundomys is only known with certainty from the Vallesian (late MN9-MN10) of France, Spain, and Portugal. It is characterized by the development of lophodonty and moderate hypsodonty in their cheek teeth. A number of other cricetids show arvicoline features so that the exact relationships of Rotundomys with respect to arvicolines remains to be determined [5]

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Conclusion