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LDH: Funda??o de Amparo ? Pesquisa do Estado de S?o Paulo (FAPESP) post-doctoral fellowship 2019/14606-4 and Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) doctoral scholarship; EH: FAPESP post-doctoral fellowships 2014/25743-9 and 2018/09321-8; BSWC: Natural Sciences and Engineering Research Council (NSERC) Discovery grant; OFG: Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) Research Productivity Fellowship; PRKG: CNPq grant 484228/2011-0; DFV: FAPESP grant 2014/26818-2, CAPES ProAmazonia 3263/2013-19 and CNPq 309409/2015-2. Universidade de S?o Paulo. Instituto de Psicologia. Departamento de Psicologia Experimental. S?o Paulo, SP, Brazil. Universidade de S?o Paulo. Instituto de Psicologia. Departamento de Psicologia Experimental. S?o Paulo, SP, Brazil / Hospital Israelita Albert Einstein. Instituto de Ensino e Pesquisa. S?o Paulo, SP, Brazil. Universidade de S?o Paulo. Instituto de Psicologia. Departamento de Psicologia Experimental. S?o Paulo, SP, Brazil. University of Toronto. Department of Cell and System Biology. Toronto, Canada. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Centro Nacional de Primatas. Ananindeua, PA, Brasil. Universidade Federal do Par?. N?cleo de Medicina Tropical. Bel?m, PA, Brazil / Universidade Federal do Par?. Instituto de Ci?ncias Biol?gicas. Bel?m, PA, Brazil. Universidade Federal do Par?. N?cleo de Medicina Tropical. Bel?m, PA, Brazil / Universidade Federal do Par?. Instituto de Ci?ncias Biol?gicas. Bel?m, PA, Brazil. Universidade Federal do Par?. N?cleo de Teoria e Pesquisa do Comportamento. Bel?m, PA, Brazil Universidade Federal do Par?. N?cleo de Teoria e Pesquisa do Comportamento. Bel?m, PA, Brazil Universidade de S?o Paulo. Instituto de Psicologia. Departamento de Psicologia Experimental. S?o Paulo, SP, Brazil / Hospital Israelita Albert Einstein. Instituto de Ensino e Pesquisa. S?o Paulo, SP, Brazil. Primate colour vision depends on a matrix of photoreceptors, a neuronal post receptoral structure and a combination of genes that culminate in different sensitivity through the visual spectrum. Along with a common cone opsin gene for short wavelengths (sws1), Neotropical primates (Platyrrhini) have only one cone opsin gene for medium-long wavelengths (mws/lws) per X chromosome while Paleotropical primates (Catarrhini), including humans, have two active genes. Therefore, while female platyrrhines may be trichromats, males are always dichromats. The genus Alouatta is inferred to be an exception to this rule, as electrophysiological, behavioural and molecular analyses indicated a potential for male trichromacy in this genus. However, it is very important to ascertain by a combination of genetic and behavioural analyses whether this potential translates in terms of colour discrimination capability. We evaluated two howler monkeys (Alouatta spp.), one male A. caraya and one female A. seniculus, using a combination of genetic analysis of the opsin gene sequences and a behavioral colour discrimination test not previously used in this genus. Both individuals completed the behavioural test with performances typical of trichromatic colour vision and the genetic analysis of the swsl, mws, and Iws opsin genes revealed three different opsin sequences in both subjects. These results are consistent with uniform trichromacy in both male and female, with presumed spectral sensitivity peaks similar to Catarrhini, at similar to 430 nm, 532 nm, and 563 nm for S-, M- and L-cones, respectively.

Albinism is a rare phenotype that affects the pigmentation in eyes, hair, and skin. The effects of albinism in color vision are still unclear. Our study aimed to evaluate the color vision phenotype and genotype of an albino capuchin monkey. An adult albino male capuchin monkey (Sapajus apella) had the L and M opsin gene analyzed, and was trained in a behavioral task of color discrimination. Color discrimination thresholds were determined along 20 chromatic axes around the background chromaticity. A color discrimination ellipse was drawn by interpolation among these thresholds. The albino monkey’s behavioral color discrimination ellipse showed poor discrimination along the red–green axis indicating a deutan phenotype. Genetic analysis revealed only the presence of the L gene in the albino monkey. This result did not differ from that obtained with ten previously tested non-albino monkeys. Behavioral and molecular analyses agreed that the albino capuchin monkey had color vision similar to that of non-albino dichromat monkeys, suggesting no influence of albinism on color discrimination.

The identification of color vision types in primates is fundamental to understanding the evolution and biological function of color perception. The Hard, Randy, and Rittler (HRR) pseudoisochromatic test categorizes human color vision types successfully. Here we provide an experimental setup to employ HRR in a nonhuman primate, the capuchin (Cebus libidinosus), a platyrrhine with polymorphic color vision. The HRR test consists of plates with a matrix composed of gray circles that vary in size and brightness. Differently colored circles form a geometric shape (X, O, or Δ) that is discriminated visually from the gray background pattern. The ability to identify these shapes determines the type of dyschromatopsy (deficiency in color vision). We tested six capuchins in their own cages under natural sunlight. The subjects chose between two HRR plates in each trial: one with the gray pattern only and the other with a colored shape, presented on the left or right side at random. We presented the test 40 times and calculated the 95 % confidence limits for chance performance based on the binomial test. We also genotyped all subjects for exons 3 and 5 of the X-linked opsin genes. The HRR test diagnosed two subjects as protan dichromats (missing or defective L-cone), three as deutan dichromats (missing or defective M-cone), and one female as trichromat. Genetic analysis supported the behavioral data for all subjects. These findings show that the HRR test can be applied to diagnose color vision in nonhuman primates.