Hypoptopoma sternoptychum (Schaefer 1996)

This species is distinguished from all congeners except H. spectabile, by the pattern of abdominal plates, consisting of a pair of slender plates posterior to the coracoids followed by a series of 1-3 unpaired medial abdominal plates (vs. 2 or 3 series of abdominal plates); by having the posterior process of the coracoid strongly curved, its distal tip pointing dorsally (vs. posterior process smoothly curved and distal tip pointing posterodorsally); and by the absence of basipterygium fenestrae (vs. with basipterygium fenestrae). This species is distinguished from H. spectabile by the presence of thoracic plates; greater number of total lateral plates 21-22 (21) (vs. 20-22 (20)); greater number of dentary teeth, 21-37 (30) (vs. 20-31 (24)); greater dorsal interorbital distance with mean dorsal interorbital distance 63.5 (vs. 58.5); pelvic fin placed more posteriorly, mean pectoral-pelvic distance 15.5 (vs. 12.7); and longer pectoral fin, length reaching or surpassing the anal-fin origin, the mean pectoral-fin spine length 39.3 (vs. 29.8) (Ref. 84367).

Dorsal spines (total): 1; Dorsal soft rays (total): 7; Analsoft rays: 6; Vertebrae: 26