Author: Gilbert & Hubbs, 1920
Hymenocephalus gracilis Gilbert & Hubbs, 1920
Diagnosis: body slender and cylindrical, head as wide as deep, the dermal bones thin and weak. Snout bluntly rounded; mouth large, upper jaw reaching back beyond eye, oblique and subterminal, teeth small, none enlarged, the band in lower jaw narrower than that in upper; gillrakers 16-18, chin barbel present. First dorsal fin with 11-13 finrays, the second finray weakly denticulated; second dorsal fin beginning some distance behind, with very short finrays; pectoral fin with 15-18 finrays; pelvic fin with 7-9 finrays. Scales large, thin and cycloid; but almost always shed. Pyloric caeca 11-17 (usually 13). Light organ along belly elongate, with an external circular lens-shaped body at each end. Colour: head and most of lower surface of body silvery, a silver streak down midflanks, as well as a line of point spots (sometimes with other irregular lines of spots above and below); narrow black streaks run across leading edge of snout, upper margin of orbits, inner margins of lips and inner edges of lower jaw; fins clear or dusky, bases of paired fins black; mouth and gill cavity blackish; transverse striated lines on gular membrane and similar silver and dark lines on sides of isthmus, shoulder and belly. Size: to 13 cm TL.
Habitat: benthopelagic (at 160 345 m off Morocco). Food: planktonic crustaceans. Reproducfion: no data.
Distribution: Atlantic off Morocco. Elsewhere, tropical western North Atlantic, also western Pacific (southern Japan, South China Sea off Luzon).
Eggs, larvae and young stages. No data.
Otoliths (sagitta). No data.