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Animals 2018, 8(10), 178;

Duetting Patterns of Titi Monkeys (Primates, Pitheciidae: Callicebinae) and Relationships with Phylogeny

Museo de Historia Natural Noel Kempff Mercado, Santa Cruz de la Sierra 2489, Bolivia
Department of Biological Sciences, Marshall University, Huntington, WV 25755, USA
Departamento de Biologia, Universidade Federal Rural de Pernambuco, Recife 52171-900, PE, Brazil
Proyecto Mono Tocón, Moyobamba 22001, Perú
Wildlife Conservation Society, La Paz 3-35181, Bolivia
Department of Anthropology, University of Texas, Austin, TX 78712, USA
Carrera de Biología, Universidad Mayor de San Andrés, La Paz 6042, Bolivia
Department of Anthropology and School of Forestry & Environmental Studies, Yale University, New Haven, CT 06520, USA
Author to whom correspondence should be addressed.
Received: 12 September 2018 / Revised: 28 September 2018 / Accepted: 10 October 2018 / Published: 13 October 2018
(This article belongs to the Special Issue Animal Communication)
PDF [5533 KB, uploaded 19 October 2018]

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Titi monkeys—a diversified group of pair-bonded, territorial neotropical primates exhibiting biparental care—produce elaborate, powerful vocal duets used for long-range communication. While the callicebine taxonomy has been centered mainly on the biogeography, morphology, anatomy, and genetics of titi populations, vocal attributes have received little attention as potentially informative markers of phylogenetic relationships. We conducted acoustic analysis of callicebine loud calls recorded from ten species of titis at sites in Bolivia, Peru, and Ecuador and found four distinct patterns of duetting that only partially match three major clades identified in recent molecular genetic studies. In particular, we found that the loud calls of the San Martin titi monkey, P. oenanthe, and the Urubamba brown titi, P. urubambensis, strikingly differ from putative relatives within the donacophilus lineage. Our findings highlight interplay between genes and environment on the expression of vocal behavior and suggest that closer interaction between taxonomists, ethologists, and molecular biologists should be rewarding in resolving the callicebine phylogeny. Such concerted efforts, in turn, will most likely generate valuable recommendations for the conservation of some endangered populations of titi monkeys, such as the vocally distinctive San Martin titi.


Long-range vocal communication in socially monogamous titi monkeys is mediated by the production of loud, advertising calls in the form of solos, duets, and choruses. We conducted a power spectral analysis of duets and choruses (simply “duets” hereafter) followed by linear discriminant analysis using three acoustic parameters—dominant frequency of the combined signal, duet sequence duration, and pant call rate—comparing the coordinated vocalizations recorded from 36 family groups at 18 sites in Bolivia, Peru and Ecuador. Our analysis identified four distinct duetting patterns: (1) a donacophilus pattern, sensu stricto, characteristic of P. donacophilus, P. pallescens, P. olallae, and P. modestus; (2) a moloch pattern comprising P. discolor, P. toppini, P. aureipalatii, and P. urubambensis; (3) a torquatus pattern exemplified by the duet of Cheracebus lucifer; and (4) the distinctive duet of P. oenanthe, a putative member of the donacophilus group, which is characterized by a mix of broadband and narrowband syllables, many of which are unique to this species. We also document a sex-related difference in the bellow-pant phrase combination among the three taxa sampled from the moloch lineage. Our data reveal a presumptive taxonomic incoherence illustrated by the distinctive loud calls of both P. urubambensis and P. oenanthe within the donacophilus lineage, sensu largo. The results are discussed in light of recent reassessments of the callicebine phylogeny, based on a suite of genetic studies, and the potential contribution of environmental influences, including habitat acoustics and social learning. A better knowledge of callicebine loud calls may also impact the conservation of critically endangered populations, such as the vocally distinctive Peruvian endemic, the San Martin titi, P. oenanthe. View Full-Text
Keywords: Plecturocebus; Cheracebus; Callicebus; vocal communication; taxonomy; conservation Plecturocebus; Cheracebus; Callicebus; vocal communication; taxonomy; conservation

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Adret, P.; Dingess, K.A.; Caselli, C.B.; Vermeer, J.; Martínez, J.; Luna Amancio, J.C.; Van Kuijk, S.M.; Hernani Lineros, L.M.; Wallace, R.B.; Fernandez-Duque, E.; Di Fiore, A. Duetting Patterns of Titi Monkeys (Primates, Pitheciidae: Callicebinae) and Relationships with Phylogeny. Animals 2018, 8, 178.

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