Mammalian Biology 76 (2011) 417–427 Contents lists available at ScienceDirect Mammalian Biology journal homepage: www.elsevier.de/mambio Original Investigation A cytotaxonomic and DNA-based survey of rodents from Northern Cameroon and Western Chad Gauthier Dobigny a,b,∗ , Caroline Tatard c , Mamadou Kane d , Philippe Gauthier a , Carine Brouat a , Khalilou Ba d , Jean-Marc Duplantier a a IRD, Centre de Biologie et de Gestion des Populations (CBGP, UMR IRD-INRA-CIRAD-Montpellier SupAgro), Campus de Baillarguet CS30016, 34988 Montferrier-sur-Lez, France b IRD, Centre Régional Agrhymet, BP11011, Niamey, Niger c INRA, CBGP (UMR IRD-INRA-CIRAD-Montpellier SupAgro), Campus de Baillarguet CS30016, 34988 Montferrier-sur-Lez, France d IRD, CBGP (UMR IRD-INRA-CIRAD-Montpellier SupAgro), Campus ISRA-IRD de Dakar-Bel-Air, BP 1386, Dakar CP 18524, Senegal article info Article history: Received 7 May 2010 Accepted 12 October 2010 Keywords: African biodiversity Praomys Taterillus lacustris Cytotaxonomy Molecular systematics abstract Rodent diagnosis has long remained obscured by the co-existence of cryptic species in many lineages. However, alternative and accessible methods, such as cytotaxonomy and DNA-based methods, are now available that allow biologists to accurately monitor biodiversity through the production of well docu- mented lists of unambiguously species-specific identifications. As a continuation of our previous surveys of West African rodents, we here present the first rodent inventory of rodents from Northern Cameroon (as well as one locality in Western Chad) that fully relies on karyotypic and/or sequencing data. Doing so, we assess the presence of 18 species in this poorly documented region. Among them, we found several African spiny mice that could be referred as to A. johannis, a poorly documented species. Moreover, sev- eral Arvicanthis individuals could be aggregated with previously studied but still enigmatic specimens of ANI-2 and ANI-4 sensu Volobouev et al. (2002a,b), thus suggesting that they may all belong to one single species, namely A. rufinus. In addition, one specimen was shown to belong to a new biological species (Praomys sp.) that will deserve further taxonomic investigations. Finally, several Taterillus specimens were found with 2n = 28–30 chromosomes and a XX/XY1Y2 sex chromosome system. On the basis of these new results as well as a reinterpretation of previously published data, we propose to refer these individuals as to the poorly documented Taterillus lacustris. Altogether, our data suggest that Northern Cameroon is a “phylogeographical node” for several rodent lineages which may be at least partly explained by the past changes within the Lake Chad basin. Keeping this in mind, there is little doubt that biodiversity will undergo important modifications in the coming decades, following the increasing aridity and the drastic reduction of Lake Chad. © 2010 Deutsche Gesellschaft für Säugetierkunde. Published by Elsevier GmbH. All rights reserved. Introduction Although rodents represent half of the mammalian specific diversity (Wilson and Reeder 2005; see Werdelin and Sanders 2010, for a review in Africa), systematics within the Order is still unsta- ble, mainly due to the co-existence of sibling species, i.e. that are morphologically similar but reproductively isolated. Such a matter of fact has led to the confusion/misidentification of many African rodents, but can now be sorted out through the use of alternative tools, such as genetic ones. Following the pioneer works of Matthey and Petter in the 60s (e.g., Matthey 1963, 1966, 1969; Petter 1971), cytotaxonomy (karyotype analysis applied to species discrimina- ∗ Corresponding author at: IRD, Centre Régional Agrhymet, BP11011, Niamey, Niger. E-mail address: Gauthier.Dobigny@ird.fr (G. Dobigny). tion and identification) has been greatly helpful in identifying cryptic biodiversity in African rodents (e.g., Acomys: Volobouev et al. 1996, 2002a; Arvicanthis: Volobouev et al. 2002b; Mastomys: Granjon et al. 1997b; Volobouev et al. 2002a; Mus subgenus Nanno- mys: Veyrunes et al. 2004; Otomys: Rambau et al. 2001; Gerbilliscus: Volobouev et al. 2007; Granjon 2005; Aniskin et al. 2006; Taterillus: Dobigny et al. 2002a, 2003). It relies on the assumption that suffi- ciently divergent karyotypes can ensure reproductive isolation and thus sign species-level differences. Later on, investigations focusing on short stretches of DNA sequences, especially the mitochondrial cytochrome b gene, have also contributed to similar taxonomic clarifications (e.g., Mastomys: Lecompte et al. 2006; Dobigny et al. 2008; Acomys: Barome et al. 2000; Nicolas et al. 2009). Altogether, these approaches allow biologists to depict a more and more pre- cise picture of rodent diversity throughout Africa, and lead to an increasing amount of unambiguous list of species in several sub- Saharan West African countries such as Mauritania (Granjon et al. 1616-5047/$ – see front matter © 2010 Deutsche Gesellschaft für Säugetierkunde. Published by Elsevier GmbH. All rights reserved. doi:10.1016/j.mambio.2010.10.002