Hybridization Between Neotropical Primates with Contrasting Sexual Dichromatism Italo Mourthe 1,2,3 & Rhaysa A. Trindade 2 & Lucas M. Aguiar 4 & Tatiane C. Trigo 5 & Júlio César Bicca-Marques 1 & Sandro L. Bonatto 2 Received: 16 January 2017 /Accepted: 20 October 2017 # Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract Hybridization is relatively well documented among Old World primates, but poorly investigated among New World monkeys. We investigated hybridization between the sexually dichromatic howlers Alouatta caraya and Alouatta guariba clamitans, whose lineages diverged ca. 5 million years ago. These taxa show allopatric distributions with a few recently discovered narrow contact zones. We collected 169 individual fecal samples of A. caraya and A. g. clamitans within (N = 121) and outside (N = 48) two contact zones in southern Brazil. We used mtDNA and Y-chromosome (SRY gene) sequences, and three diagnostic microsatellite loci to investigate their parental origin. We found 33 individuals (27%) with evidence of hybrid origin in the contact zones. Thirteen individuals presented mtDNA of A. caraya origin and Y-chromosome of A. g. clamitans origin and eight individuals have the opposite combination of markers. We assigned the hybrid origin of the remaining 12 individuals based on the discrepancy between their uniparental markers and microsatellite data, or a combination of diagnostic alleles of both species. This is the first Int J Primatol https://doi.org/10.1007/s10764-017-0011-9 Handling Editor: Guest Editors of the Special Issue * Italo Mourthe imourthe@gmail.com 1 Laboratório de Primatologia, Escola de Ciências, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre 90619-900, Brazil 2 Laboratório de Biologia Genômica e Molecular, Escola de Ciências, PUCRS, Porto Alegre 90619-900, Brazil 3 Present address: Programa de Pós-graduação em Biodiversidade e Conservação, Universidade Federal do Pará, Altamira 68372-040, Brazil 4 Instituto Latino-Americano de Ciências da Vida e da Natureza, Universidade Federal da Integração Latino-Americana, Foz do Iguaçu, Brazil 5 Setor de Mastozoologia, Museu de Ciências Naturais, Fundação Zoobotânica do Rio Grande do Sul, Porto Alegre, Brazil