The Collaborative International Dictionary of English v.0.48:

monocystic \mon`o*cys"tic\, a. [See Mono-, and Cyst.]
   (Zool.)
   Of or pertaining to a division (Monocystidea) of the
   protozoan order Gregarinida, in which the body consists of
   one sac.
   [1913 Webster]