This species is distinguished from its congeners except G. brianne, by the following set of characters: caudal fin is rhomboid shaped with mid-caudal rays produced; lateral-line disjunct; anal-fin spines are short; differs from G. brianne by the absence of scales on dentary (vs. present), measurements of several body parts, caudal fin rhomboid shaped in both species, but posterior halves of dorsalmost and ventralmost borders of fin slightly concave in G. xanthostigma (vs. gently rounded to convex) and a bright yellow spot at upper base of pectoral fin (vs. absent) (Ref. 116412).