Thie species is distinguished from its congeners by the following set of of characters: first dorsal-fin origin slightly anterior to pelvic-fin origin (vs. well anterior in P. campechiensis); dorsal fins subequal (vs. first dorsal fin smaller in P. campechiensis and first dorsal fin slightly larger in P. xaniurus); upper caudal crest of denticles separated from lateral denticles by naked strip (vs. barely separated in P. xaniurus); lower caudal crest of denticles well developed and extending until last third of ventral caudal-fin lobe (vs. extending until the end of ventral caudal-fin lobe in P. campechiensis and reduced or absent in P. xaniurus; labial furrows discontinuous (vs. continuous in P. campechiensis and P. xaniurus); anal-fin base 1.6 times anal-fin height (vs. 3 times in P. campechiensis and 2.2-2.5 in P. xaniurus); pre-first dorsal-fin length 4.3 times interdorsal space (vs. 4.9 times in P. xaniurus); prenarial length 0.8-1.1 times in prepectoral length (vs. 0.3 times in P. campechiensis); mouth width 2.6 times mouth length (vs. 1.9 times in P. campechiensis); monospondylous precaudal centra 38 (vs. 39 in P. campechiensis), and total vertebrae counts 121-122 (vs. 111 in P. campechiensis and 109-121 in P. xaniurus) (Ref. 125615).