This species is distinguished from its congeners by the following characters: body black, dark olive, or dark gray covered by conspicuous greenish-yellow small dots of similar size on head, trunk, and fins (vs. head with small spots, and large whitish-yellow spots or blotches posteriorly towards caudal fin, with dorsal, caudal, and anal fins covered by dark brown spots over rays); differs further from its congeners except H. tricornis by a narrow, barshaped connection strut between anterior process of compound pterotic and main body, leaving a large posterior gap (vs. connection strut shaped as a continuous sheet); differs from its congeners except H. xikrin by the pectoral-fin spine length 32.1-38.4% of SL (vs. 25.1-29.9% in tricornis, 24.5-30.9% in munduruku and 27.4-30.8% of SL in xavante); differs from xikrin by the transverse processes of first and second dorsal-fin pterygiophores sutured to each other (vs. no contact between the transverse processes of first and second pterygiophores); differs from xavante by having a narrow nasal bone plate (vs. nasal broad, sometimes slightly triangular); the nuchal plate exposed and covered by odontodes (vs. plate covered by thick skin and usually lacking odontodes); differs from tricornis by having five branched rays on the anal-fin (vs. four) (Ref. 125999).