Siamang

The Siamang (Symphalangus syndactylus) is a tailless, arboreal, black furred gibbon native to the forests of Malaysia, Thailand, and Sumatra. The largest of the lesser apes, 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.
The Siamang is distinctive for two reasons. The first is that two fingers on each hand are fused together — hence the name "syndactylus", from the Ancient Greek sun-, "united" + daktulos "finger". The second is the large "gular sac" (found in both male and female of the species), which is a throat pouch that can be inflated to the size of its head, allowing the Siamang to make loud resonating calls or songs.
There may be two subspecies of the Siamang. If so, they are the nominate Sumatran Siamang (S. s. syndactylus) and the Malaysian Siamang (S. s. continentis, in peninsular Malaysia). Otherwise, the Malaysian individuals are only a population. The Siamang is the only gibbon which occurs sympatrically with other gibbons; its two ranges are entirely within the combined ranges of the Agile Gibbon and the Lar Gibbon. Although the siamang is given a different name than other gibbons, this division is not cladistically sound, since the genus Nomascus split from the rest of the gibbons before Symphalangus split
The Siamang can live up to 30+ years in captivity.
While the illegal pet trade takes a toll on wild populations, the principal threat to the Siamang is habitat loss in both Malaysia and Sumatra. Palm oil production is clearing large swathes of forest, reducing the habitat of the Siamang, along with that of other species such as the Sumatran Tiger.