The Shell is large for the genus (maximum length 25 mm) and broadly lanceolate. The spire is high and acute, consisting of one and one-half narrow, convex nuclear whorls and eight or nine broad, strongly dorsoventrally flattened postnucicar whorls. The suture is deeply impressed but is largely obscured by varical buttresses. The body whorl is very broadly fusoid, The aperture is small and ovate, with a barely perceptible anal sulcus. The outer apertural lip is weakly erect; immediately behind it is a more or less broadly expanded varical wing. The inner surface of the outer lip bears five. or six rather weak denticles corresponding roughly to the spiral cords on the shell's exterior. The columellar lip is smooth, detached, and weakly erect anteriorly. The siphonal canal is moderately long, narrowly open, and dorsally recurved.
The body whorl bears two expanded, lateral varical flanges and two minor, costate varices. Two additional varices, seen in the first three or four whorls, recede with later growth and eventually are represented solely by buttresses at the suture. The spiral sculpture consists of five broad weak cords.
The shell is translucent gray-white, with a nebulous brown spiral band on the upper portion of each whorl, grading into white below. The whole is covered by a thick, flat-white, axially striate, and spirally incised intritacalx. The aperture is porcelaneous white. The muricine radular dentition shows a fivecusped rachidian tooth with the lengths of the central, lateral, and intermediate cusps in the ratio of 4:3:1. The operculum is typically muricine.
Radwin & D'Attilio, 1976. Original description.

This species has been known for some time but bas heen assumed by many workers to be A. pyramidalis (see Keen, 1958; Radwin and D'Attilio, 1971). It may be distinguished from A. pyramidalis in the broadness and flatness of the whorls, the degree of expansion and dorsal reflection of the varical flanges, and the intritacalx, with its spiral, as well as axial, sculpture.

Holotype: length 12.4 mm, width 6.3 mm; Largest paratype: length 25 mm, width 13.3 mm; Smallest imature paratype: length 7,7 mm, width 4.3 mm.

Southern end of the Gulf of California to Costa Rica.