Diagnosis
Cylindrical shell with aperture 80-88% of shell height and a very narrow umbilicus. Unforked foot. Radula formula 1.1.1. Radula large; median teeth about 0.06 mm wide in specimens 2.5-2.75 mm high.
Shell, general: Cylindrical, widest part between 1/3 and 3/4 of height from base, smooth except for fine growth lines. White. Height to at least 2.85 mm. Height/width 1.7-1.8. About 1.6 teleoconch whorls on a 2 mm high specimen (inferred).
Spire: Acuminate with projecting protoconch. Shoulders rounded or moderately angled, sepa¬rated from preceding whorl by an unrimmed. groove.
Aperture: 80-88% of shell height. Widest about 1/4 ofheight fiom base. Outer lip evenly to hyperbolicaly rounded in lower 1/4 of shell, running straight above until it forms a small arch at top of aperture. Inner lip running in a shallow curve from top of aperture to about halfway to base, where it joins the columella at an angle of about 150°, continuing in an almost straight line to base.
Umbilicus: Open, 6-9% of shell width, with abapertural rim.
Protoconch: Apparently letithotrophic type, about 0.4 mm wide; number of whorls uncertain. Angle between teleoconch and protoconch 120-150°.
External anatomy: Foot unforked posteriorly. Eyes visible.
Radula : Formula 1.1.1, symmetrical. Median tooth more than 0.06 mm wide in specimens with a shell height of 2.5-3 mm.

Diaphana pfefferi is very similar to D. paessleri, the shell of which is, however, more oval or pentagonal in outline, and which has a smaller radula. It also shows outward similarity to the northern D. makarovi, but that species has a radula with marginal teeth and no visible eyes.

Type locality: Georgia, 54°22'S, 36°28'W, 12-15 m, sand and algae. Known only from South Georgia at depths of 12-15 m (Strebel 1908).