This species is distinguished from its congeners except Tetragonopterus anostomus by the number of gill rakers on the upper and lower limbs of the first gill arch, 10-12 and 18-20, respectively (vs. 8-10 and 12-14); differs from T. anostomus by the terminal mouth (vs. subsuperior); differs from T. anostomus, T. kuluene, T. juruena, T. denticulatus in the number of principal teeth in the dentary 4 (vs. 5-6) and also by having larger and more robust teeth (vs. thinner and sharper teeth); differs from T. argenteus by the number of predorsal scales 7-9 (vs. 111-17); differs from T. carvalhoi by having a spot on the caudal peduncle that is round (vs. lozenge-shaped spot); differs from T. ommatus by the teeth on the maxilla 0-2 (vs. 7-8) and having a centered mark on the caudal peduncle (vs. limited to the posterior portion of the caudal peduncle); differs from T. rarus, T. georgiae by the scale rows between lateral line and pelvic-fin origin 3.5 (vs. 4.5-5.5); differs from T. rarus by the lack of dark stripes on the lateral surface of the body (vs. the presence of such stripes) (Ref. 124043).

Description: Dorsal-fin rays ii,9; anal-fin rays v, 32-35; pectoral fin with i,12-14; pelvic-fin rays i, 7; scales in longitudinal series 30-33; and scale rows between lateral line and pelvic-fin origin 3·5 (Ref. 93280).