The Collaborative International Dictionary of English v.0.48:

Ateles \At"e*les\, n. [Gr. ? incomplete; 'a priv. + ?
   completion.] (Zool.)
   A genus of American monkeys with prehensile tails, and having
   the thumb wanting or rudimentary. See Spider monkey, and
   Coaita.
   [1913 Webster] Atelets sauce

WordNet (r) 3.0 (2006):

Ateles
    n 1: spider monkeys [syn: Ateles, genus Ateles]