[2][3] It is listed as an endangered species because it is believed to have undergone a decline of more than 50% in the prior three generations due to loss of forest habitat and loss of mature individuals to hunting.

[2] The subspecies is distinguished by sharply distinct dark and light color forms, both having a ring of white hair around the face, with hands and feet white sometimes as far as the wrists and ankles, and the hair much longer than in other subspecies.

[2] The dark form is very dark chocolate brown, the tips of the hairs being blackish and their bases silvery-brown, whereas the light form is creamy-white, with the basal one-quarter to one-third of the hairs light gray.

[2] Its range is confined to northern and part of northeastern Thailand.

[2] In the southwest part of its range, its distribution abuts that of the pileated gibbon, Hylobates pileatus.