The Collaborative International Dictionary of English v.0.48:

ameban \ameban\ adj.
   1. of or pertaining to amoebae. Same as amoeban. [Also
      spelled amoeban.]

   Syn: amoebic, amebic, amoeban, amoebous, amebous
        [WordNet 1.5]

   2. Caused by amoebae; -- of diseases; the more common word is
      amoebic. Amoebic dysentry is caused by the amoeba
      Entamoeba histolytica.

   Syn: amoebic, amebic
        [PJC]

WordNet (r) 3.0 (2006):

amoeban
    adj 1: pertaining to or resembling amoebae; "amoebic dysentery"
           [syn: amoebic, amebic, amoeban, ameban,
           amoebous, amebous]