What is any South American monkey of the genus Mycetes. Many species are known. They are arboreal in their habits, and are noted for the loud, discordant howling in which they indulge at night called?

howler — (Zoöl.) Any South American monkey of the genus Mycetes. Many species are known. They are arboreal in their habits, and are noted for the loud, discordant howling in which they indulge at night. (Webster's 1913.)