This species can be recognized by the brush-cut, rectangular patch of short bristles in the lip throat. The resolution and soft focus of these photos do not produce images sharp enough to see these bristles in detail, and although they can't be resolved, they can be barely seen in one photo. A similar species, P. zambesiaca is described as having a sharply pointed midlobe apex, wheras P. lawrenceana has a broadly blunted, bilobed midlobe apex. In the description of P. zambesiaca, it is pointed out that this species is variable and there are often intermediate forms which make it difficult to draw a dividing line. In many of the available photos of either species, the lip apices may be seen that are sharply pointed or bilobed.