1.  systematist(n = noun.person) taxonomer, taxonomist - a biologist who specializes in the classification of organisms into groups on the basis of their structure and origin and behavior;
is a kind of biologist, life scientist
has particulars: lumper, divider, splitter
Derived forms noun systematics₁, noun systematism₁

2.  systematist(n = noun.person) orderer, systematiser, systematizer, systemiser, systemizer - an organizer who puts things in order; "Aristotle was a great orderer of ideas"
is a kind of arranger, organiser, organizer
Derived form noun systematism₁

1.  One who forms a system, or reduces to system. [1913 Webster]

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