Why are baboons, geladas, and mandrills in the macaque subfamily the only monkey species whose standardized Chinese names do not end with "monkey"?

为何科名尾字为「猴」的生物里，只有猕猴亚科的狒狒属、狮尾狒属、山魈属，其规范中文种名尾字非「猴」？

A public trend signal observed across 1 source.