The dotted butterflyfish is a bright golden yellow colour with a vertical, teardrop shaped bar running through the eye.

[4] The dotted butterflyfish was first formally described in 1855 by the Dutch physician, ichthyologist and herpetologist Pieter Bleeker (1819-1878) with the type locality being given as Cocos (Keeling) Islands, an Australian Indian Ocean territory.

[5] The specific name semeion means "banner" and is thought to be a reference to the long dorsal fin filament.

[6] This species belongs to the large subgenus Rabdophorus which might warrant recognition as a distinct genus.

In this group, it appears to represent a distinct lineage, with the saddle butterflyfish (C. ephippium) perhaps the only somewhat closely related species.