photo by A. Mootnick

S. syndactylus adult male

photo by C. Klein

S. syndactylus subadult female

Symphalangus syndactylus (Raffles, 1822). Siamang.
   General Description: Siamangs are the largest gibbon. They have a stocky build, broad chest, and show some sexual dimorphism with respect to body and skull size (Hooijer, 1952; Groves, 1972). Both sexes have long, black hair which often includes faint white or cream chin hairs. The crown hair lies flat and swirls laterally above the brow. Siamangs have webbed second and third toes (Schultz, 1933), from which the genus and species names are derived. Both sexes have a large, inflatable throat sac, which may serve to amplify vocalizations. Males have a short penis and a large genital tuft and females have a short clitoris (Groves, 1972). Infants are the same color as the parents. This genus is characterized by a diploid chromosome number of 50 (Klinger, 1963). The single extant species, Symphalangus syndactylus, is divided into two subspecies, but there are few visual features which reliably distinguish them.

  Symphalangus syndactylus is threatened in its native habitat of the mountains and southern swamp forests of Sumatra and central and western peninsular Malaysia.   Siamangs are the loudest land mammal and are characterized by their vocal sac that can  inflate to the size of their head.  We house a captive born family group.

Symphalangus syndactylus syndactylus (Raffles, 1822). Sumatran siamang.
   The Sumatran siamang appears to have a larger cranium, tooth row, and body than does the mainland subspecies. There is a shallow vertical crease down the center of the nose (preliminary observation). VanTuinen & Ledbetter (1983) found no subspecific differences in chromosomal C-banding, G-banding, or silver staining.

Symphalangus syndactylus continentis (Thomas, 1908). Malaysian siamang.
   The Malaysian siamang appears to have a smaller cranium, tooth row, and body than does the Sumatran subspecies.