The Collaborative International Dictionary of English v.0.48:

Systematist \Sys"tem*a*tist\, n. [Cf. F. syst['e]matiste.]
   1. One who forms a system, or reduces to system.
      [1913 Webster]

   2. One who adheres to a system.
      [1913 Webster]

WordNet (r) 3.0 (2006):

systematist
    n 1: a biologist who specializes in the classification of
         organisms into groups on the basis of their structure and
         origin and behavior [syn: taxonomist, taxonomer,
         systematist]
    2: an organizer who puts things in order; "Aristotle was a great
       orderer of ideas" [syn: orderer, systematizer,
       systematiser, systemizer, systemiser, systematist]