Mitromorphidae
The Mitromorphidae have small to medium-sized shells with a high biconic mitriform shape, a paucispiral or multispiral protoconch up to 4.5 whorls, a short or indistinct siphonal canal, narrow aperture with up to 3 columellar pleats, indistinct anal sinus on a weakly pronounced subsutural ramp, fairly smooth surface with spiral sculptural elements. There is no operculum, and the radula is relatively short, hypodermic in character with awl-shaped teeth, a swollen solid basal region, and may have a weak barb at the terminal end of the radular tooth.
Bouchet, Kantor et al. elevated in 2011 the subfamily Mitromorphinae (which at that point had been placed in the family Conidae) to the rank of family. This was based on a cladistical analysis of shell morphology, radular characteristics, anatomical characters, and a dataset of molecular sequences of three gene fragments.
Mitrolumninae was established as a substitute name for Diptychomitrinae. Mitromorphidae and Mitrolumninae were published the same year but Mitromorphidae (19 May 1904) has priority over Mitrolumninae (31 August 1904).
Bouchet et al. 2011 state: Shell small- to medium-sized, 3–30 mm, usually 5–10 mm high, biconic, of mitriform shape. Sculpture rather smooth, with dominant spiral elements. Aperture narrow, with or without 1– 3 columellar pleats, sometimes with denticles within. Siphonal canal short or indistinct. Anal sinus from indistinct to rather shallow indentation on weakly pronounced subsutural ramp. Protoconch multispiral or paucispiral, up to 4.5 smooth whorls.
In Lving taxa:
No operculum. Radula of hypodermic, marginal, relatively short, awlshaped teeth with large swollen solid basal part. Distinct ligaments present, short. Tooth canal opening subterminally or laterally. At their tip, teeth can have a weak barb.