The Collaborative International Dictionary of English v.0.48:

Acaudate \A*cau"date\, a. [Pref. a- not + caudate.]
   Tailless.
   [1913 Webster]

WordNet (r) 3.0 (2006):

acaudate
    adj 1: lacking a tail or taillike appendage [syn: acaudate,
           acaudal] [ant: caudate, caudated]