Hylobates syndactylus; Print; The siamang (Symphalangus syndactylus) is an arboreal black-furred gibbon native to the forests of Indonesia; Malaysia and Thailand. The largest of the gibbons; the siamang can be twice the size of other gibbons; reaching 1 m in height; and weighing up to 14 kg. The siamang is the only species in the genus Symphalangus.; 1700-1880