Species, subspecies, or color morphs? Reconsidering the taxonomy of Callicebus Thomas, 1903 in the Purus–Madeira interfluvium

Abstract

There have been recent disagreements as to how many taxa of titi monkeys, genus Callicebus, occur in the region between the Purus and Madeira rivers in western Brazilian Amazonia. Three parapatric taxa were proposed for the area: Callicebus caligatus, Callicebus stephennashi, and Callicebus dubius, but the latter has recently been considered a synonym of C. caligatus, even though both form monophyletic groups and are morphologically distinct. We analyzed the geographic variation in the pelage of Callicebus occurring between the Madeira and Purus rivers and concluded that the phenotypes attributed to C. caligatus and C. dubius are not individual morphs, but rather well-marked and geographically restricted varieties. For this reason, we classify Callicebus caligatus as a polytypic species with two subspecies: Callicebus caligatus caligatus and Callicebus caligatus dubius. This classification is corroborated by molecular evidence as well. The morphological and distributional data indicate that Callicebus stephennashi is a hybrid form of C. c. caligatus and C. c. dubius, due to the presence of intermediate characters. Therefore, until more precise locality records are provided and further evidence is presented, we consider Callicebus stephennashi to be a homonym of the two parental forms.

Terrestrial Behavior in Titi Monkeys (Callicebus, Cheracebus, and Plecturocebus): Potential Correlates, Patterns, and Differences between Genera

“…Previously included in a single genus, Callicebus, titi monkeys were recently split into three genera (Callicebus, Cheracebus, and Plecturocebus) based on phylogenetic and divergence-time analyses using molecular data (Byrne et al 2016), and in accordance with long-recognized geographically-based species groupings (van Roosmalen et al 2002). The 35 species currently described (Boubli et al 2019;Byrne et al 2016;Serrano-Villavicencio et al 2017;van Roosmalen et al 2002) are distributed throughout Amazonia into Paraguay, with a discontinuous distribution in eastern Brazil. Titi monkeys inhabit a variety of habitats, ranging from Andean pre-montane forests (e.g., Plecturocebus oenanthe: Bóveda-Penalba et al 2009), lowland rainforests (e.g., Plecturocebus lucifer: Kinzey et al 1977), and dry semi-deciduous forests (e.g., Callicebus barbarabrownae: terrestrial behavior in titi monkeys has been conducted to date; although members of the group have long been reported to use the ground (Kinzey 1977;Mason 1966).…”

Extension of the geographic distribution of Plecturocebus baptista (Pitheciidae, Primates) and a possible hybrid zone with Plecturocebus hoffmannsi: evolutionary and conservation implications

“…Collectively, the titis are the most specious group of Neotropical primates, with 35 known species Boubli et al 2019). The large number of species, the remote areas of occurrence, ACTA AMAZONICA poor representation in museum collections, combined with frequently complex intra-and inter-population variation (Serrano-Villavicencio et al 2017), have led to a complex taxonomic history for this group (Hershkovitz 1990;Roosmalen et al 2002), and new species continue to be described (Boubli et al 2019). Therefore, it is essential to have well-defined geographical and taxonomic bases for effective conservation in this primate group (Carneiro et al 2018).…”

River Network Rearrangements in Amazonia Shake Biogeography and Civil Security

“…2, 3A, 3B, S6), a connection that disappeared so recently that the biogeographical pattern it created still lingers. A similar example is the contact zone between two subspecies of the titi monkey Callicebus caligatus (66), found between the Mucuím and Ipixuna rivers. The area lacks any obvious dispersal barriers today, but this is where the Madeira river seems to have had its most recent connection to the Purus (Figs.…”