phyletic
adjective
phy·let·ic fī-ˈle-tik 
: of or relating to evolutionary change in a single line of descent without branching
phyletically
fī-ˈle-ti-k(ə-)lē
adverb 
Word History
Etymology
International Scientific Vocabulary phyl- + -etic (as in genetic)
First Known Use
1877, in the meaning defined above
Medical Definition
phyletic
adjective
phy·let·ic fī-ˈlet-ik
: of or relating to the course of evolutionary or phylogenetic development