The pronotum may be pale with only the median vitta dark, or it may have in addition narrow obscurely darker borders. In the latter case the resemblance to
P. nigricans may cause some uncertainty in identification unless the genitalia are examined. The median vitta may become quite wide, covering all, or nearly all, of the convex surface. Sometimes a combination of wider vitta and darker borders results in the complete elimination of pale lateral areas. These various color patterns intergrade and do not permit a definite segregation of color phases. In the female the terminal ventral segment is broadly, very feebly, arcuately emarginate, as compared to angulately notched in
P. nigricans.
(1)