(ダーウィンの動物大図鑑 はろ～！あにまる - 動物大図鑑)
The muriquis, also known as woolly spider monkeys, are the monkeys of the genus Brachyteles. They are closely related to both the spider monkeys and the woolly monkeys. There are two species, the southern (B. arachnoides) and northern muriqui (B. hypoxanthus). They are the two largest species of New World monkeys, and the northern species is one of the most endangered of all the world's monkeys. They are found only in the Atlantic coast forests of southeastern Brazil at altitudes ranging from sea level to 1500 m (495 ft).
Muriquis are folivores (herbivores), but will also eat significant amounts of fruit and flowers in the rainy season, as well as bark, bamboo, ferns, nectar, pollen, and seeds.
As is common to many platyrrhines, males are philopatric and females tend to move out into other groups at the onset of adolescence around 5 to 7 years of age, later reaching maturity at an average age of 11 years. On average, males reach maturity in half this time.
Observed group sizes range from 8 to 43, and contain plentiful numbers of both males and females. Muriquis are polygamous, and unlike many other primates males spend large periods of time together without significant aggressive encounters. As such, they are also not territorial.