This species is distinguished from P. carrancas and P. hyptiorhachis by the absence of a postdorsal ridge (vs. presence of a postdorsal ridge); differs from all its congeners, except P. hyptiorhachis, by having less vertebrae, 29 (vs. 30 in P. brachyrhyncha and P. cepta; 31 in P. carrancas and P. rudolphi); differs from P. carrancas, P. hyptiorhachis and P. rudolphi by having teeth with a minute lateral cusp (vs. unicuspid teeth); differs from P. brachyrhyncha and P. hyptiorhachis by having the anterior profile of the head elliptical in dorsal view (vs. rounded); differs from P. brachyrhyncha by having the tip of the snout naked (vs. the tip of the snout completely covered with small odontodes), a lower predorsal length (41.0-44.8 mm SL vs. 45.6-48.9 mm SL), higher number of premaxillary teeth (35-48 vs. 28-36), and higher number of dentary teeth (33-49 vs. 26-36); differs from P. cepta by lacking small plates distributed on the thorax and abdomen (Ref. 100791).