The Collaborative International Dictionary of English v.0.48:

Leontocebus \Leontocebus\ prop. n.
   A genus of marmosets including some of the tamarins. Called
   also Leontopithecus and Leontideus.

   Syn: genus Leontocebus, genus Leontideus, genus
        Leontopithecus.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Leontocebus
    n 1: tamarins [syn: Leontocebus, genus Leontocebus, genus
         Leontideus]