An Update of the Geographic Distribution of the Red-Mantled Saddle-Back Tamarin, Leontocebus lagonotus (Callitrichidae), in Ecuador

Understanding the geographic distributions of primates is necessary to ensure effective conservation strategies. Nonetheless, many gaps persist in information regarding the range limits of platyrrhines. Leontocebus lagonotus is no exception; it is one of the least studied primates in Ecuador and its geographic limits are poorly known. We obtained 296 records of its presence in Ecuador from field studies (between 1996 and 2020), museums, the literature, and databases. Of these, we validated 211 records and used 106 (excluding grouped points) to determine the potential distribution of this species using an ecological niche model (MaxEnt). The model suggested that the species’ distribution in Ecuador covers 64,028 km². Based on confirmed data, the extent of occurrence was 38,226 km², but after updating it with layers of remaining vegetation (2018), we determined that the current distribution is 32,643 km² (a 15% reduction). Our findings reduce the range proposed for the species in Ecuador, suggesting that areas north of the Napo River, the north-central area of Yasuní National Park, and the far eastern part of Waorani Ethnic Reserve were never part of the species’ range. We also identified the southern boundaries of its distribution, where the Paute-Upano and Cangaime-Morona rivers form a natural barrier. Its distribution in Peru possibly reaches the south of the Morona and Santiago rivers. We recommend a similar approach for other platyrrhines, particularly those under threat, for better implementation of conservation efforts.