Hoolock or white-browed gibbon. The genus Bunopithecus has one species.
Males have black hair with a pale brow that flicks up at the ends.
The female's face ring is wide above the eyes, turns upwards at the ends, and becomes thin as it encircles the muzzle. Shorter hairs on the sides of the neck give this gibbon's face a triangular appearance. The muzzle is larger compared to other gibbon species with a thin tuft of hair at the chin. The chest region is narrow. Ischial callosities are heavily furred.