3.3.4.3 Alouatta seniculus juara Elliot, 1910

The Juruá red howler monkey is distributed through the western portion of the Brazilian Amazon, in the states of Acre and Amazonas, south of the Rio Solimões and west of the Rio Purus (Fig. 3.1). Its range extends to Peru, but the range limits are not known. The taxonomic position of juara has been debated, sometimes considering it a junior synonym of A. seniculus (e.g., Cabrera 1957), other times including it as one of its subspecies (e.g., Groves 2001) or as a distinct species (e.g., Elliot 1910; Gregorin 2006). These discrepancies are mainly due to the lack of comprehensive studies. Gregorin (2006) examined 31 specimens from Brazil that occur within the supposed range of this taxon. He found statistical differences on morphometric variables between juara and A. macconnelli and A. nigerrima, but he did not present data for these types of analyses comparing juara to A. seniculus. Nonetheless, he found differences in pelage coloration between juara and A. seniculus from northern Colombia. Regarding hyoid morphology, Gregorin (2006) found a high similarity between juara and A. seniculus and concluded that they must be phylogenetically proximate.

Lima and Seuánez (1991) reported on the karyotype of one individual sampled in Tefé, in the range of juara, and mentioned that the karyotype of this individual was “basically the same as that of the Colombian specimens” analyzed by Yunis et al. (1976) and that “this finding indicates that the geographic range of this subspecies might extend further south to the Solimões River.” Gregorin (2006) used this information as evidence supporting the distinction of juara from A. macconnelli and A. nigerrima, but it remains unclear whether this taxon is distinct from A. seniculus.