Adults: 10.6-14.8 cm TL. Body wet weight of individuals measuring 10.8-14.8 cm TL, 4.3-7.0 g. Body proportions, as percentage of TL [based on 22 specimens, TL range inferred to be 10.6-14.8 cm, Álvarez del Villar (1966)]: prebranchial length, 12.0-14.2; branchial length, 9.3-11.6; trunk length, 40.3-50.7; tail length, 26.7-32.9; eye length, 2.0 (holotype); disc length, 5.7 (holotype). Urogenital papilla length, as a percentage of branchial length, in four spawning males measuring 11.5-12.6 cm TL, 7.7-12.5. Trunk myomeres, 60-65. Dentition: supraoral lamina, 2 unicuspid teeth; infraoral lamina, 5-9 unicuspid teeth of which 5 are large and 0-4 are small (87% of specimens possess both large and small cusps); endolaterals on each side 3-4; endolateral formula, typically 2-2-2-2 or 1-1-1, but one to six endolaterals may be missing; 3 rows of anterials; first row of anterials, 2 unicuspid teeth; 1 row of exolaterals; 1 row of posterials; first row of posterials, 8 unicuspid and 1 bicuspid teeth; transverse lingual lamina, 19 unicuspid teeth, the median one slightly enlarged; longitudinal lingual laminae with undetermined number of teeth. Extent of caudal fin pigmentation,75% or more (Ref. 89241).