From Kook Science

a.k.a. Patas monkey, dancing red monkey, hussar monkey
Country Nigeria
Region(s) Yorubaland

Ijimere is an appellation of Yoruba origin for the patas monkey (erythrocebus patas), and thus is not a crypto-hominid. It has been connected with the religious practices of Egúngún, the voice of the monkey being mimicked by masked figures representing the dead, as well as being "esteemed a clever physician" such that medicine men would tame them and make apparent consultations.

"A Clever Physician"

The representing forms are human beings of the exact height and figure of the deceased, covered from head to foot with cloths similar to those in which the said deceased was known to have been buried, completely masked and speaking with an unnatural tone of voice. This feigned voice is said to be in imitation of that of a species of monkey called Ijimere. That animal is regarded with superstitious reverence, the power of walking erect and talking being ascribed to it and is esteemed a clever physician. Some professed "medicine men" usually tame and keep one of these creatures , and pretend to receive instructions and inspirations from it.