Author: Regan & Trewavas, 1930
Leptostomias haplocaulus Regan & Trewavas, 1930
Diagnosis: barbel without filaments at base of stem; no filaments along stem until just before terminal bulb; bulb with a series of simple filaments from stem at base of bulb to about 2/3 distance to distal end; a bilateral series of filaments at distal end. Photophores in ventral row between pectoral and pelvic fin insertions (PV) about 41; in lateral row to before pelvic insertion (OV) about 41. Colour: head and body black. Size: to more than 37.5 cm.
Habitat, etc.: see family.
Distribution: possibly throughout the area to about 45° N. Elsewhere, recorded southward to about 18° N; also, western Atlantic from about 24° to 30° N between 60° and 70° W.
Note: this species may be part of the problem complex of species mentioned under Leptostomias longibarba.