In prorocentroids (desmokonts) this region is located on the anterior end of the right valve within a notched area (V-shaped triangular depression). It consists of plates or platelets around one or two periflagellar pores, the auxilliary pore (A) and the flagellar pore (F). Accessory pores, apical spines, periflagellar collars and/or periflagellar plates may also be present.

Alternative form for periflagellar area : flagellar pore area.