Nomascus or crested gibbons is the second-most speciose genus of gibbons. Originally, this genus was a subgenus of Hylobates, and all individuals were considered one species,the Black crested gibbon. Species within Nomascus are characterized by 52 chromosomes. Some species are all black, some are light with a distinct black tuft of crown fur, and some have distinct, light-colored cheek patches. Nomascus is found from southern China (Yunnan) to southern Vietnam, and also on Hainan Island. One species, the Northern white-cheeked gibbon, has been deemed "the most critically endangered ape species in the world". All species in this genus are endangered or critically endangered.