 Their clade is considered basal to the order Phasmatodea; that is, many scientists believe that Timema-type stick insects represent the earliest "branch" to diverge from the phylogenetic tree that gave rise to all the stick insects of Phasmatodea.This primal distinction is referenced by the name "Euphasmatodea", which is given to all the clades of Phasmatodea other than the suborder Timematodea.Twenty-one species have been described; in addition there is at least one undescribed species known to exist