Oligosarcus jenynsii (Günther 1864)

Material examined. 1 exemplar; 53.7 mm SL. CI FML 7831, 1 ex, 27° 19’ 07.5”S, 65° 41’ 51.2”W Jaya River.

Identification. Presence of 54-62 perforated scales in lateral series; 8-11 longitudinal series of scales between the lateral line and the origin of the dorsal fin; 21-23 horizontal series of scales around the caudal peduncle; short snout, the same length as the diameter of the eye; jaws are identical, although in some specimens the upper jaw slightly longer; jaws with conical and caniniform teeth, maxilla with 19-28 teeth; anal fin with 26-30 rays (Serra et al., 2014; Almirón et al., 2015).