Gibbon Conservation Center

About Gibbons,  Symphalangus,  Hoolock,  Hylobates 

GENUS NOMASCUS  (Miller, 1933)   Crested gibbon    

The crown hair of males and immature (black) females stands erect, with the male's hair being longer in the crown's center. The nose is long and slender (Groves, 1972). Females have an elongated clitoris and males have a long baculum (Groves, 1984); external genitalia of the two sexes appear similar. Infants are pale at birth. Starting at the fingers, toes, and face ring, infants gradually change to a black phase. Near the age of sexual maturity, females change back to the light phase while males remain black (Pocock, 1905; Delacour, 1951; DePutte & Lecierc-Cassan, 1981; Liu, et al., 1989; Couturier & Lernould, 1991). With the exception of the buff-cheeked gibbon (N. gabriellae), males have a small throat sac. This genus is characterized by a diploid chromosome number of 52. 

Nomascus concolor concolor (Harlan, 1826). Western crested gibbon. Area: N. Vietnam, between the Black and  Red River, Central Yunnan.   
Males are black, with crown hair growing upwards and slightly longer in the center, with longer body hair and few white hairs at the corner of the mouth.  Females can have from buffish to a light tawny body hair and black-brown or black occipital streak (Ma, Wang, and Poirier, 1988; Geissmann, 1989). Females have a black crown streak and dark hair on the ventrum (Geissmann, 1995) creating an inverted triangle.
Females could also be buff-tan with black on first digits, chin, with few black hairs on the genitals, pelvis, legs, around the ears and a creamy-buff throat. Females have a white patch of hair above the mouth and below the eyes.

Nomascus concolor lu (Delacour, 1951). Laotian black-crested gibbon. Area: NW Laos.   
Males have a trace of grey mixed throughout the body hair.  They have been reported to have a trace of a silver streak above the temples. However, the description of a subspecific pattern is complicated by the inclusion of subadults undergoing color transitions (Delacour, 1951). Two specimens that were collected at Ban Nam Khueng may be Nomascus concolor lu.  The overall pelage of the adult female is tawny-buff with a black crown. The chest is buff with a few black hairs extending from the chest and gradually darkening in the genital region, creating a circular pattern.  There are a few black hairs on the fingers and toes.  The chin is black with few black hairs on throat, and with a few black hairs above the ears.  The face ring is slightly lighter than the surrounding hair, and there are no long guard hairs. The male has short black hair mixed with longer guard hairs. Until live specimens can be studied it is questionable if this subspecies is not Nomascus c. concolor (Geissmann, in press).

Nomascus nasutus (Kunkel d’Herculais, 1884). Eastern crested gibbon. Area: NE Vietnam, east of the Red River and southern China.    Males and immature have blackish hair, with slightly brownish hair on the chest, or as much as from the throat to the abdomen. Females are a buffish to a buffish gray color with a long wide black crown streak that can go past the nape, and extends to the brow and tapers to a thin face ring, and becoming thicker at the chin. There is a narrow blackish brown chest plate slightly wider than the face, beginning at the throat and tapering at the top of the abdomen. Article in our newsletter by Tilo Nadler about this species.

Nomascus hainanus (Thomas, 1892). Hainan gibbon. Area: Hainan Island, China   

Males have short, black hair, and the crown hair is not as obvious (Pocock, 1905; Groves, 1972; Ma, Wang, and Poirier, 1988).  Females have a black crown patch, with all other body hair being a brown-yellow, with no black hairs on the limbs (Ma, Wang, and Poirier, 1988), and white patch of hair above the mouth and below the eyes.

Article naming this species among the rarest primates in the world, from IUCN.

Nomascus leucogenys (Ogilby, 1840). Northern white-cheeked gibbon.   

The male cheek patches connect under a black chin and extend up to the top of the ear. Females range in color from dark to light buff to creamy orange often diffused with tan, grey, or black hairs, with a small-to-medium-length black crown patch. Females can have brown-black genitals and black hairs on the tips of fingers and toes. A trace of the crown patch can extend between the scapulae. Females are sometimes larger than are males.   

Nomascus leucogenys is extinct in southern Yunnan, and nearly extinct in northern Vietnam, although they can be found in a small portion of Laos.  We currently house three pairs, one of which has two offspring.

Nomascus siki (Delacour, 1951). Southern white-cheeked gibbon.  Area: Central Vietnam, Southern Laos. Males have small white cheek patches that extend as far up as the eye's corner, and thin white hair partially encircles the upper lip and totally encircles the lower lip, terminating in a black chin. Adult females are more similar in appearance to adult female N. leucogenys than to N. gabriellae females (Geissmann, 1995).

Nomascus gabriellae (Thomas, 1909). Southern buff-cheeked gibbon.  Area: Southern Vietnam, Southern Laos, Eastern Cambodia.   

Males have small, light buff cheek patches that extend to the bottom of the orbital ridge and can be slightly separated at the throat. Females are generally smaller than N. leucogenys females and have a black fringe at the ears. Females are generally buff to strawberry-buff and can have a very slight grizzling of darker hairs on the chest, on edges and tips of fingers and toes, and on the outer forearm. Adult females may have slight red-brown genital hairs, and usually there is a trace of a white fringe encircling the face. Females are typically smaller than males.