Is the New Primate Genus Rungwecebus a Baboon? Dietmar Zinner1*, Michael L. Arnold2, Christian Roos3 1 Cognitive Ethology, Deutsches Primatenzentrum, Go¨ ttingen, Germany, 2 Department of Genetics, University of Georgia, Athens, Georgia, United States of America, 3 Primate Genetics and Gene Bank of Primates, Deutsches Primatenzentrum, Go¨ ttingen, Germany Abstract Background: In 2005, a new primate species from Tanzania, the kipunji, was described and recognized as a member of the mangabey genus Lophocebus. However, molecular investigations based upon a number of papionins, including a limited sample of baboons of mainly unknown geographic origin, identified the kipunji as a sister taxon to Papio and not as a member of Lophocebus. Accordingly, the kipunji was separated into its own monotypic genus, Rungwecebus. Methodology/Principal Findings: We compare available mitochondrial and nuclear sequence data from the voucher specimen of Rungwecebus to other papionin lineages, including a set of geographically proximal (parapatric) baboon samples. Based on mitochondrial sequence data the kipunji clusters with baboon lineages that lie nearest to it geographically, i.e. populations of yellow and chacma baboons from south-eastern Africa, and thus does not represent a sister taxon to Papio. Nuclear data support a Papio+Rungwecebus clade, but it remains questionable whether Rungwecebus represents a sister taxon to Papio, or whether it is nested within the genus as depicted by the mitochondrial phylogeny. Conclusions/Significance: Our study clearly supports a close relationship between Rungwecebus and Papio and might indicate that the kipunji is congeneric with baboon species. However, due to its morphological and ecological uniqueness Rungwecebus more likely represents a sister lineage to Papio and experienced later introgressive hybridization. Presumably, male (proto-)kipunjis reproduced with sympatric female baboons. Subsequent backcrossing of the hybrids with kipunjis would have resulted in a population with a nuclear kipunji genome, but which retained the yellow/chacma baboon mitochondrial genome. Since only one kipunji specimen was studied, it remains unclear whether all members of the new genus have been impacted by intergeneric introgression or rather only some populations. Further studies with additional Rungwecebus samples are necessary to elucidate the complete evolutionary history of this newly-described primate genus. Citation: Zinner D, Arnold ML, Roos C (2009) Is the New Primate Genus Rungwecebus a Baboon?. PLoS ONE 4(3): e4859. doi:10.1371/journal.pone.0004859 Editor: Vincent Laudet, Ecole Normale Supe´rieure de Lyon, France Received December 16, 2008; Accepted February 12, 2009; Published March 19, 2009 Copyright: 2009 Zinner et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: German Science Foundation Grant (DFG ZI 548/3-1) supported DZ. National Science Foundation Grant DEB-0345123 supported MLA. The funding agencies had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: dzinner@gwdg.de Introduction In 2005, a new primate species from Tanzania, the kipunji, was described and originally recognized as a member of the mangabey genus Lophocebus, mainly based on its arboreality and non- contrasting black eyelids [1]. However, subsequent molecular studies suggested that the kipunji was more closely related to Papio, rather than to one of the two mangabey genera or any other member of the Papionini tribe [2]. Based on these findings, the kipunji was recently placed into its own genus, Rungwecebus [2]. Besides genetic evidence, the uniqueness of Rungwecebus was also supported by morphological, acoustic, behavioral and ecological characteristics [2–4]. Nevertheless, the classification of Rungwecebus as a new genus has been questioned [5]. To place Rungwecebus kipunji phylogenetically, Davenport et al. [2] generated sequences of three mitochondrial (cytochrome oxidase subunit I, COI; cytochrome oxidase subunit II, COII; 12SrRNA) and two nuclear (a 1,3 galactosyltransferase, a 1,3-GT; Y chromosomal testis-specific protein, TSPY) loci of a single voucher specimen. In 2008, another three nuclear loci (autosomal lipoprotein, LPA; autosomal gene encoding CD4; X chromosomal region, Xq13.3) of Rungwecebus became available and the TSPY sequence data were expanded [6]. In both studies, the Rungwecebus data were compared with orthologous sequences of other Old World monkeys, deposited in GenBank. However, the GenBank data did not cover the full taxonomic and geographic range of Papio (Figure 1). In particular, sequences from Papio of southern Tanzania and neighboring regions, those geographically nearest to the range of Rungwecebus, were not available for both analyses [2,6]. Furthermore, many of the Papio sequences in GenBank are of unknown geographic origin because they derived from captive animals. In the course of a study on the evolution and phylogeography of Papio, we compared the available nuclear and mitochondrial sequence data of Rungwecebus with orthologous data of baboons from known geographic origin and representatives of all other papionin genera. Results The main result of our study is that, based on mitochondrial sequence variation, Rungwecebus does not constitute a sister taxon to Papio but clusters within Papio. This result contrasts with those of both Davenport et al. [2] and Olson et al. [6]. However, this relationship becomes obvious only when baboons from parapatric populations to Rungwecebus from south-east Africa are included in the study. The analysis of nuclear data provides limited power due PLoS ONE | www.plosone.org 1 March 2009 | Volume 4 | Issue 3 | e4859