Symphurus maculopinnis is distinguished from all other species of Symphurus by the combination of a 1–2–2–2–1 ID pattern, 14 caudal-fin rays, 3+6 abdominal vertebrae, 49 total vertebrae, about 89 scales in a longitudinal row, 92 dorsal-fin rays, 77 anal-fin rays, a blunt squarish snout, blind-side lower jaw with thick lip with conspicuous plicae, and by conspicuous ocellated (sometimes partially) black spots on the posterior dorsal and anal fins (Ref. 87974).