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).