A new species of Callicebus Thomas, 1903 (Primates, Pitheciidae) from the states of Mato Grosso and Pará, Brazil

a new species of titi monkey, genus callicebus thomas, 1903, is described based on four individuals, one from a small tributary of the left bank of rio teles pires, northern state of mato grosso, and three others from largo do souza, rio iriri, pará, brazil. the new species belongs to the callicebus moloch species group, and the main diagnostic characteristics of the new species are the whitish forehead, sideburns and beard coloration, which are contiguous, forming a frame around the blackish face; overall body pelage coloration is pale grayish-brown agouti; hands, feet and tip of the tail whitish; belly and inner sides of fore and hind limbs uniformly orange. the pattern of pelage coloration and qualitative and quantitative skull morphology are described and compared to the other species of the callicebus moloch group. species of the callicebus moloch group show great similarity in skull morphology and morphometrics, making the external morphological characters, specially the chromatic fields, the most reliable diagnostic trait to identify the species.