One Genus or Two? Evaluating Whether Gracile and Robust Capuchin Monkeys are Validly Classified as Separate Genera Based on Craniofacial Shape

Abstract Assessments of whether closely related species should be classified into more than one genus have been a longstanding source controversy in primatology. For example, researchers hold differing opinions about cebine or two genera. In this study, we investigated craniofacial shape is reliable taxonomic indicator among cebines and statistically evaluated the magnitude differences observed gracile robust capuchin consistent with two-genus framework. We quantify using 3D landmark data taken from 72 surface models, representing five ( Cebus albifrons, C. capucinus, olivaceus , (Sapajus) libidinosus (S.) macrocephalus ). find that although significant exist between capuchins all four regions (face palate, basicranium, calvarium, frontal region calvarium), pairs does not support being separate The calvarium face palate show highest groups, both are good predictors, showing correct classification rates 97% 96%, respectively. At species-level, only measure consistently shows high (84-97% for combined-sex analyses). Our findings suggest often assigned to Sapajus may appropriately considered as under single-genus framework based on evidence.