Gualda-Barros et al. 2012
Callicebus vieirai sp. nov.
Type locality: Rio Renato, tributary of Rio Teles Pires (right bank), nearby the city of Cláudia, state of Mato Grosso, Brazil (11°33’00.15”S, 55°10’59.98”W; about 370 m above sea level).
Distribution: Known from three distant localities of the Brazilian states of Mato Grosso and Pará. In the state of Mato Grosso, the species occurs in the type locality, and a nearby Ribeirão Carmelita (tributary of Rio Azul) (11°01’00.15”S, 54°28’59.99”W) where two specimens were sighted by one of us (M.K.) but were not collected. Besides, the species possibly occurs in a third locality, Juína, in the northwestern Mato Grosso, where a male and a female were seized by Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA) and further were led to the Parque Zoológico Municipal Quinzinho de Barros (Sorocaba, state of São Paulo; Rodrigo Teixeira, pers. comm.). However, there is not more information that indicates a more precise point in Juína region where the animals were caught. In the state of Pará, Callicebus vieirai occurs in Largo do Souza, Rio Iriri (04°00’S, 53°00’W), in Rio Xingu.
Description: It is a medium-sized species of the C. moloch group, with overall coloration pale grayish brown agouti mainly in the crown, nape, dorsum, tail and the dorsal sides of the limbs; hands, feet and tip of tail white; belly and ventral sides of limbs orangish. Clearly distinct from other members of the species group by the white coloration present in the forehead, the crown and the beard, surrounding the dark face.
Description of holotype: Length of head and body smaller than length of tail, which is 60% of total length of the specimen. Forehead, sideburns and beard white, surrounding the blackish pigmented face; some white vibrissae present in the face around mouth and nostrils; between face and forehead there is a very narrow stripe of vibrissae with larger blackish bands alternating to narrower white bands. Crown and nape indistinct, pale grayish agouti, lighter than the dorsum, and showing shorter hairs (1 cm). Dorsum and flanks pale grayish-brown agouti with longer hairs (5 cm). Coloration of proximal outer surface of fore and hind limbs is indistinct from that of dorsum and flanks, but becomes graduallylighter and whitish on the distal portions; hands and feet (cheiridia) are whitish. Venter and inner sides of fore and hind limbs uniformly orangish, hairs not banded. Base of tail darker than dorsum, but in the middle region the pattern become similar to the dorsum, and the tip of tail is whitish. Face, ventral side of hands and feet, ears and genitals blackish.
Variation: In the holotype, the white frame present in the forehead is wide and evident, whereas in specimens from Rio Iriri it is narrow and less evident. The grayish-brown agouti coloration of the dorsum is darker in the paratypes, especially in MZUSP 25441. Inner side of fore limbs is slightly more orangish in MZUSP 25441 and whitish in MZUSP 25442. Hands and feet are grayish in MZUSP 25441 and MZUSP 25442. Chest and venter slightly more orangish in MZUSP 22441 and MZUSP 22443.
Comparisons: The species of the C. moloch group are distributed around the area of occurence of C. vieirai. Another species, C. pallescens, of the C. donacophilus Group is distributed south to C. vieirai and has a similar coloration pattern. C. vieirai is readily distinguished from C. moloch by the white beard and sideburns, the whitish agouti hands, feet and outer side of limbs, light orange throat, chest and belly, while in C. moloch the beard and sideburns are orange, the throat, chest and belly are dark orange, the hands and feet are buffy, and outer side of limbs are buffy or grayish to pale brown agouti. C. vieirai is distinguished from C. cinerascens by the pale grayish-brown agouti coloration of dorsum, and crown, sideburns, beard, hands and feet are white or whitish, while C. cinerascens shows reddish brown agouti coloration in dorsum, and crown, sideburns, beard, hands and feet are grayish agouti. C. vieirai is distinguished from C. baptista by white or whitish agouti forehead, white sideburns, pale grayish brown agouti dorsum, pale yellowish coloration in the throat, chest and belly, whitish agouti hands and feet, instead of a blackish to grayish agouti forehead, dark reddish brown sideburns, throat, chest and belly, blackish to grayish agouti dorsum, and blackish to grayish hands and feet. C. vieirai differs from C. brunneus by the overall coloration of body a pale grayish brown agouti instead of dark brown agouti, and crown, sideburns, beard, hands and feet white or whitish instead dark brown. C. vieirai differs from C. hoffmannsi by possessing a grayish tail instead of blackish, by the white sideburns and beard instead of yellowish or orangish, and hands and feet white or whitish instead dark grayish agouti. C. vieirai differs from C. pallescens by the white or whitish agouti forehead instead pale grayish agouti or orangish agouti, and by the absence of a perceptible white ear tufs.
Remarks: According to our data, C. vieirai has at least records from three separated geographical samples. Two of them are located in the State of Mato Grosso, nearby the city of Cláudia, including the Rio Renato, Ribeirão Carmelita and surrounding areas, and another in the region of Juína, while a third sample occurs in the Largo do Souza, Rio Iriri, center-northwestern Pará. The records from Cláudia and surroundings and from Largo do Souza occur within the area of distribution of C. moloch, suggesting the existence of an overlap in their respective geographic range. Nevertheless, the characters of C. vieirai are not within the variation observed in the specimens of C. moloch studied. The latter species shows a broader distribution, occupying the easternmost portion of general distribution of the group, occurring from the west bank of Rio Tocantins-Araguaia to the east bank of the Río Tapajós in Pará, southwards to the headwaters of the Rios Araguaia, Xingu, and Tapajós in northern Mato Grosso and westwards to the eastern bank of the Rio Ji-Paraná in Rondônia and east bank of the Rio Aripuanã in Amazonas (de Vivo, 1985; de Vivo, unpublished data; Hershkovitz, 1990).