There is the presence of three swellings or angular shoulders of the thorax that are each located between the indistinct thoracic ribs which occupy slight furrows in the thoracic wall. The cephalis of P. praetextum is separated from the thorax by a more distinct stricture, each blade of the three-bladed feet is latticed for a greater distance in its proximal portion, and the outward projecting blade of each foot originates from higher up on the thorax and is convex outward proximally, merging with the outline of the thorax. Four small, nearly circular collar pores separated by thick bars present a different aspect from those of the preceding species. The abdomen is similar to that of Pterocanium prosperinae and is separated from the thorax by a distinct constriction and an internal septal ring.
Length of cephalis 17-25 µm, of thorax 49-59 µm, of abdomen 0-31 µm; breadth of cephalis 18-27 µm, of thorax at level of shoulders 79-92 µm; length of apical horn 31-53 µm, of vertical spine 4-10 µm, of feet 49-166 µm; maximum distance between tips of feet 49-166 µm.