Knowledge shortfalls for titi monkey: A poorly known clade of small-bodied South American primates

Abstract

Titi monkeys (Callicebus, Cheracebus, and Plecturocebus) comprise the most species-rich group of primates in South America. Thirty-six currently recognized species composing this group inhabit a multitude of habitats across most of South America. While field-based and laboratory research has provided insights into the behavior, ecology, and physiology of some titis, multiple knowledge gaps regarding their biodiversity patterns persist. Here, we provide an overview of titi research and identify their biodiversity knowledge shortfalls. Using online databases, we collated the literature of all titi studies published up to December 31, 2021. We compiled 521 publications, with 48 % representing in situ field studies of the monkeys. The majority of field-based publications focused on studies conducted in Brazil and Peru. We found that research efforts have increased in recent decades, as indicated by the increased number of publications on titis. However, given the large number of species and their wide distribution across South America, there is limited information about most of these species and their geographic ranges. By highlighting the focal points where conservation-related data are still required, our findings demonstrate the importance of expanding research efforts and investment on the full extent of titi species and their entire geographic regions; doing so will help fill the knowledge shortfalls rather than solely advancing the study of a restricted range of topics in one or two habitats or countries. These advances will contribute to fill knowledge gaps through the creation/expansion of data repositories, citizen science programs, and increased financial support to maintain long-term data collection.