This species is distinguished from its congeners by the following characted: presence of a light brown body pigmentation (vs. pale straw pigmentation in P. gimbeli, and dark brown in P. gymnotus); one row of conical teeth on the dentary (vs. two); edentulous premaxilla (vs. presence of teeth); ossified second basibranchial (vs. unossified in P. gimbeli, condition unknown in P. gymnotus). It further differs from P. gimbeli by the absence of a distinct swelling on the chin (vs. presence of this structure), the total anal-fin rays (124-142 vs. 171–198), and the prepectoral-fin distance (14.1-17.0% of LEA vs. 10.3-13.5); from P. gymnotus by the distance from the posterior naris to the eye (1.7-3.8% of HL vs. 8.2-11.9), mouth length (12.4-27.4% of HL vs. 28.1-38.7), pectoral-fin length (72.7-89.0% of HL vs. 60.4-70.7) (Ref. 83661).