title: Phylogenetic relationships of the New World titi monkeys (Callicebus): first appraisal of taxonomy based on molecular evidence.
abstract: BACKGROUND
  Titi monkeys, Callicebus, comprise the most species-rich primate genus-34 species are currently recognised, five of them described since 2005. The lack of molecular data for titi monkeys has meant that little is known of their phylogenetic relationships and divergence times. To clarify their evolutionary history, we assembled a large molecular dataset by sequencing 20 nuclear and two mitochondrial loci for 15 species, including representatives from all recognised species groups. Phylogenetic relationships were inferred using concatenated maximum likelihood and Bayesian analyses, allowing us to evaluate the current taxonomic hypothesis for the genus.
  
  
  RESULTS
  Our results show four distinct Callicebus clades, for the most part concordant with the currently recognised morphological species-groups-the torquatus group, the personatus group, the donacophilus group, and the moloch group. The cupreus and moloch groups are not monophyletic, and all species of the formerly recognized cupreus group are reassigned to the moloch group. Two of the major divergence events are dated to the Miocene. The torquatus group, the oldest radiation, diverged c. 11 Ma; and the Atlantic forest personatus group split from the ancestor of all donacophilus and moloch species at 9-8 Ma. There is little molecular evidence for the separation of Callicebus caligatus and C. dubius, and we suggest that C. dubius should be considered a junior synonym of a polymorphic C. caligatus.
  
  
  CONCLUSIONS
  Considering molecular, morphological and biogeographic evidence, we propose a new genus level taxonomy for titi monkeys: Cheracebus n. gen. in the Orinoco, Negro and upper Amazon basins (torquatus group), Callicebus Thomas, 1903, in the Atlantic Forest (personatus group), and Plecturocebus n. gen. in the Amazon basin and Chaco region (donacophilus and moloch groups).
authors.affiliation: School of Environment and Life Sciences, University of Salford, Room 315, Peel Building, Salford, UK.
authors.forename: Hazel
authors.initials: H
authors.lastname: Byrne
authors.affiliation: Conservation International, Arlington, VA USA.
authors.forename: Anthony B
authors.initials: AB
authors.lastname: Rylands
authors.affiliation: Universidade Federal do Pará, Campus Universitário de Bragança, Bragança, Pará Brazil.
authors.forename: Jeferson C
authors.initials: JC
authors.lastname: Carneiro
authors.affiliation: Department of Anthropology, Institute for Society and Genetics, University of California, Los Angeles, CA USA.
authors.forename: Jessica W Lynch
authors.initials: JW
authors.lastname: Alfaro
authors.affiliation: Evolution and Animal Genetics Laboratory, Universidade Federal do Amazonas, Manaus, Amazonas Brazil.
authors.forename: Fabricio
authors.initials: F
authors.lastname: Bertuol
authors.affiliation: Coleções Zoológicas, Instituto Nacional de Pesquisas da Amazônia, Manaus, Amazonas Brazil.
authors.forename: Maria N F
authors.initials: MN
authors.lastname: da Silva
authors.affiliation: Universidade Federal de Rondonia, Porto Velho, Rondonia Brazil.
authors.forename: Mariluce
authors.initials: M
authors.lastname: Messias
authors.affiliation: School of Archaeology & Anthropology, Australian National University, Canberra, Australia.
authors.forename: Colin P
authors.initials: CP
authors.lastname: Groves
authors.affiliation: Conservation International, Arlington, VA USA.
authors.forename: Russell A
authors.initials: RA
authors.lastname: Mittermeier
authors.affiliation: Evolution and Animal Genetics Laboratory, Universidade Federal do Amazonas, Manaus, Amazonas Brazil.
authors.forename: Izeni
authors.initials: I
authors.lastname: Farias
authors.affiliation: Evolution and Animal Genetics Laboratory, Universidade Federal do Amazonas, Manaus, Amazonas Brazil.
authors.forename: Tomas
authors.initials: T
authors.lastname: Hrbek
authors.affiliation: Universidade Federal do Pará, Campus Universitário de Bragança, Bragança, Pará Brazil.
authors.forename: Horacio
authors.initials: H
authors.lastname: Schneider
authors.affiliation: Universidade Federal do Pará, Campus Universitário de Bragança, Bragança, Pará Brazil.
authors.forename: Iracilda
authors.initials: I
authors.lastname: Sampaio
authors.affiliation: School of Environment and Life Sciences, University of Salford, Room 315, Peel Building, Salford, UK ; Coleções Zoológicas, Instituto Nacional de Pesquisas da Amazônia, Manaus, Amazonas Brazil.
authors.forename: Jean P
authors.initials: JP
authors.lastname: Boubli
keywords: Amazon; Atlantic forest; Callicebinae; Callicebus; Cheracebus; Genus-level taxonomy; Molecular phylogenetics; Platyrrhini; Plecturocebus; Titi monkey