Shell tiny to 8.4 mm, bulbous fusiform. Protoconch of 2 white glassy whorls, mamillate in shape. Shell smooth, spire outline straight. Teleoconch with 4-5 whorls, whorl outline slightly convex, suture well defined and incised, whorls sculptured with 8 rounded, raised axial ribs, interspaces between the ribs smooth and U-shaped. Characteristic fine cord on shoulder of
first two whorls distinguishing the appearance from later completely rounded whorls. Aperture broad, outer lip rounded, smooth, lirations visible within the aperture, columella with 4 folds, apex fold largest, folds gradually getting smaller towards the base, spiral cord emerging from the apical fold. Siphonal canal broad. Base colour white, reddish brown dots aligned vertically on axial ribs (2-3 per vertical line on penultimate whorl and 5-6 per vertical line on body whorl). Dotted lines covering the whole shell or only present as single lines.

Austromitra crayssaci n. sp. is comparable to A. brunneopunctata n. sp. because of its whitish shell with brown dots. But A. crayssaci n. sp. is slightly smaller (~ 8 mm vs. ~ 12 mm), has fewer axial ribs (8 vs. 12), the first two whorls are clearly distinguished from the following because of a fine spiral cord producing small nodules at the shoulder and the spiral cord and the brown dots on the surface are not aligned into two spiral rows but in vertical lines along the axial ribs.

Type Locality New Caledonia, Ile des Pins, 300-400 meters.
Known from the type locality Ile de Pins SE of New Caledonia (ARNAUD et al. 2002) and from the N W of New Caledonia.