The presence of 3 bold concentric bands on posterior part of pectoral fin differentiates this species from all other Sewellia species. Combination of characters unique to the species includes: cavity with deep post-oral skinfold around mouth; absence of dark stripes on body; origin of pelvic fin in front of the origin of dorsal fin; origin of pectoral fin behind corner of mouth; pelvic fin reaching origin of anal fin; branched pelvic-fin rays 8-16 with a row of individual serrae; absence of skin-fold between oropectoral membrane and ventral surface of head; 55 scales on lateral line (Ref. 40433).