Diagnosis: Shell with long, often broken off, caudal spine. Surface almost entirely white, hyaline, with exception of brown-red dorsal aperture rim and ventral side, along aperture. Ventral side flat. Differs from Diacria trispinosa f. trispinosa chiefly in lateral spines directed more caudally. Aperture lips well-developed. Juveniles with long dorso-lateral flattened needle-like shell with lateral sides diverging anteriorly only. Protoconch I globular, no sculpture on protoconch I or II; lateral sides of protoconch II thickened, discarded in adults. Teleoconch length 13 mm, width 11 mm, spine mark width 1.2 mm, aperture height 1.0 mm.