Diagnosis: Distinguished from all congeners except Phenacogrammus deheyni and P. concolor by the presence of a prominent anterior expansion of the first pleural rib; it is further distinguished from all congeners in the possession of 6 supraneural bones vs. 7, and a characteristic zigzag pattern of black pigmentation along and below the midline extending from the posterior border of the opercle to the base of the caudal peduncle (Ref. 127185).

Description: A small-bodied species; body relatively elongate, somewhat laterally compressed with greatest body depth, 27.0% of standard length, a little in front of dorsal-fin origin at level of pelvic-fin insertion; dorsal body profile steeply convex to dorsal fin, slightly less so to caudal-fin base; ventral profile smoothly convex between isthmus and anal-fin base, caudal peduncle longer than deep (Ref. 127185). Head length short, 23.4% of standard length, eye large, bony orbit diameter 43.9% of head length (Ref. 127185). Mouth terminal, lower jaw prominent and slightly prognathous, lower lip thick; premaxilla with two teeth in outer row, each bearing 3 cusps, positioned opposite interspaces between and alternating with 4 inner row teeth bearing 4-5 cusps; four outer row teeth on each dentary, the first 3 bearing 5 cusps, and the 4th greatly reduced in size bearing 3 cusps; two small, conical, symphyseal teeth located immediately behind outer row series on dentary (Ref. 127185). Dorsal-fin rays ii,7-8; fin positioned midway between snout and caudal-fin base, origin at, or slightly behind, pelvic-fin insertion; first two branched rays somewhat elongated but not filamentous; anal fin iii,17-18 rays; no hypertrophy or posterior curvature of anal fin in males; caudal fin forked, with 8 upper and 9 lower principal rays, no median filamentous extension (Ref.127185). Scales in longitudinal series 26-27 to caudal flexure, 4-5 transverse scales between longitudinal series and dorsal-fin origin, 3 transverse scales between longitudinal series and pelvic-fin insertion; pored scales in truncate lateral line 7-8; circumpeduncular scales 10 (Ref. 127185). Vertebral count 31-32; twelve to 13 pleural ribs, first with prominent rounded expansion on anterior face in upper third; six tubular supraneurals located between interspaces of neural spines of vertebral centra 4-10 (Ref. 127185).

Colouration: In preservation, base body colouration yellowish, darker dorsally and with an overlay of silver iridescence ventrally along flanks; snout and dorsum of head dark brownish black, cheek silver with patches of melanophores; a prominent pattern of black pigmentation encircling scales of longitudinal series along and below midline extending from posterior border of opercle to base of caudal fin, becoming broken into a zigzag band posteriorly along flanks and caudal peduncle; no trace of a humeral blotch; dorsal and adipose fin greyish black, anal fin dusky, pectoral and pelvic fins hyaline with darkly pigmented leading edges; median rays of caudal fin somewhat darker than above and below (Ref. 127185). Colouration and pigmentation shortly postmortem like that in preservation, but generally more intense (Ref. 127185).