Distinguished from other congeners except Tetragonopterus anostomus by having five principal teeth in the dentary (vs. four) as well as by having relatively smaller teeth of the dentary with pointed cusps (v. robust teeth with somewhat rounded cusps). Differs from T. anostomus by having terminal position of the mouth (vs. subsuperior). Can be diagnosed from T. anostomus and T. araguaiensis by having 13-14/8-9 gill rakers on the upper and lower limbs of the first gill arch (vs.17-20/10-12); from T. argenteus by having 8 predorsal scales (vs. 12-16); from T. carvalhoi by the presence of a rounded dark spot on the caudal peduncle (vs. a lozenge-shaped dark spot on the caudal peduncle); and from T. rarus by the lack of dark longitudinal stripes on the lateral surface of the body (vs. the presence of such stripes) (Ref. 93280).

Description: Dorsal-fin rays ii, 9; anal-fin rays v,28- v,32; pectoral- fin rays i,13-15; pelvic-fin rays i,7; scales in longitudinal series 32- 35; scale rows between lateral line and pelvic fin

origin 3·5 (Ref. 93280).