The stumptail macaques of China.

The stumptail macaque species Macaca thibetana and Macaca arctoides replace one another from north to south in subtropical and tropical China. These species differ in external and cranial characters. Neonatal pelage color is pale grayish-brown in M. thibetana and whitish in M. arctoides. In adults, ventral pelage is whitish in M. thibetana and brown in M. arctoides. The forehead and cheeks are thickly furred in adult M. thibetana and bald in M. arctoides. Facial skin color typically is sexually dimorphic in M. thibetana-buffy in males and reddish in females-and monomorphic in M. arctoides-reddish in both sexes. Head and body length, weight, relative tail length, and relative ear length all tend to average greater in M. thibetana than in M. arctoides. Skull length, rostral-postrostral ratio, and relative canine length in males average greater in M. thibetana. than in M. arctoides; relative zygomatic breadth and relative bimalar breadth average greater in M. arctoides than in M. thibetana. Reproductive anatomy in both sexes is strikingly divergent in these two species. Although these species are adapted to different climatic zones, many aspects of their natural history are generally similar, as far as is now known. One apparent behavioral difference is that M. thibetana usually sleeps in caves or rocky crevices, while M. arctoides usually sleeps in trees.