This species is distinguished by the following characters: D 8 branched fin rays; lateral line scales 30-34 (Ref. 46647); differs from its close relative, G. barreimiae by having a plain or almost plain, greenish or black flank pattern (vs. strongly mottled), with a faint dark-green lateral stripe present in some individuals (vs. absent), no orange midlateral scales on the flank (vs. present), no orange spot at the upper opercle (vs. present), dorsal-fin tip not white (vs. white), and with gill rakers on the lower limb of the first gill arch 12-14 (vs. 15-18) (Ref. 128817).