This species lacks a large pale area on the head (extending from the throat to snout) that is present in S. coelestinus. S. trispinosus has roughly homogenously-colored scales on flanks unlike in S. coelestinus where flank scales have distinct dark margins. S. trispinosus also lack the irregular bright-blue blotches on nape and around the eye. Juveniles are similarly colored as the adults, but bear a yellowish area on nape, similar to subadults of S. coelestinus (Ref. 40827).
- Moura, R.L., J.L. de Figueiredo and I. Sazima 2001 A new parrotfish (Scaridae) from Brazil, and revalidation of Sparisoma amplum (Ranzani, 1842), Sparisoma frondosum (Agassiz, 1831), Sparisoma axillare (Steindachner, 1878) and Scarus trispinosus Valenciennes, 1840. Bull. Mar. Sci. 68(3):505-524. (Ref. 40827) http://www.fishbase.org/references/FBRefSummary.php?id=40827&speccode=59490