The toque macaque (Macaca sinica) is a reddish-brown-coloured Old World monkey endemic to Sri Lanka, where it is locally known as the rilewa or rilawa (Sinhala රිළවා), (hence "rillow" in the Oxford English Dictionary). It is named for the toque-shaped whorl of hair on its head, rather like the bonnet of the related bonnet macaque. It lives in troops, sometimes numbering up to 20, and has developed into three subspecies. This is a medium-sized monkey, although it is the smallest living species of macaque. It has a head and body length of 35–62 cm (14–24 in), a tail length of 40–60 cm (16–24 in). Males, at a weight of 4.1 to 8.4 kg (9.0 to 19 lb), can occasionally attain much larger sizes than females, at a weight of 2.3 to 4.5 kg (5.1 to 9.9 lb).