The phylogeny of howler monkeys (Alouatta, Platyrrhini): reconstruction by multicolor cross-species chromosome painting.

We performed multidirectional chromosome painting in a comparative cytogenetic study of the three howler monkey species Alouatta fusca, A. caraya and A. seniculus macconnelli (Atelinae, Platyrrhini) in order to reconstruct phylogenetic relationships within this genus. Comparative genome maps between these species were established by multicolor fluorescence in-situ hybridization (FISH) employing human, Saguinus oedipus and Lagothrix lagothricha chromosome-specific probes. The three species included in this study and previously analyzed howler monkey species were subjected to a phylogenetic analysis on the basis of a data matrix comprised of 98 discrete molecular cytogenetic characters. The results revealed that howler monkeys represent the genus with the most extensive karyotype diversity within Platyrrhini so far analyzed with high levels of intraspecific chromosomal variability. Two different multiple sex chromosome systems were identified. The phylogenetic analysis indicated that Alouatta is a monophyletic clade which can be derived from a proposed ancestral Atelinae karyotype of 2n = 62 chromosomes by a chromosome fusion, a fission, a Y-autosomal translocation and a pericentric inversion. Following these suggestions, the genus Alouatta can be divided into two distinct species groups: the first includes A. caraya and A. belzebul, the second A. s. macconnelli, A. sara, A. s. arctoidea and A. fusca.