The Collaborative International Dictionary of English v.0.48:

Ixobrychus \Ixobrychus\ n.
   A genus of birds consisting of certain of the bitterns.

   Syn: genus Ixobrychus.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Ixobrychus
    n 1: bitterns [syn: Ixobrychus, genus Ixobrychus]