Shell small, white, fusiform, sharply carinate about middle of whorls. Spire considerably shorter than aperture plus canal. Hase regularly contracted, canal long. open. Whorls 4,5, including a typical asymmetrical protoconch of 1,5 whorls. Axials rather narrow, extending from suture to suture on the spire whorls but becoming obsolete across the base, 19 in number on the penultimate, 20 on the body whorl. Spiral sculpture moderate, crossing the axials, the spiral forming the keel strong and nodulous. Above the keel on the spire whorls about 4 very fine spirals are developed on the shoulder, with a weak sutural fold; on the body whorl there are about 6 fine spirals. On the spire whorls there is a second moderately strong spiral shortly above the suture. Body whorl with some 4 strong spirals below the keel and an additional 13 across the base and fasciole. The uppermost 4 spirals on the body whorl have each a fine interstitial spiral. Fine curving growth lines are well developed. Aperture long and narrow, outer lip thin, sinus wide and shallow, occupying the shoulder. Height. 6,1 mm.; diameter. 3,0mm.

This shell is of the same type as A. otagoensis Powell, which occurs in the same area in shallower water. It differs from otagoensis in the proportionately higher aperture and the much more numerous axials.