Shell of moderate size, moderately inflated, elongate-oval, smooth, shining. Beaks small, rounded, incurved, situated about anterior two-fifths. Anterior margin broadly rounded ; posterior end drawn out, very bluntly pointed high up, posterodorsal margin fairly straight, almost horizontal; ventral margin broadly curved. There is no true rostrum. Surface smooth and polished, covered with a thin, light brown epidermis. The only sculpture consists of fine, rather irregular growth lines. Hinge long and thin, somewhat concave near beaks, teeth rapidly diminishing towards the centre, 10 teeth in anterior series, 14 in posterior. The hinge line is interrupted under the beaks. Ligament entirely posterior and above the hinge line.
Length, 4,9 mm.; height, 3,2 mm.; inflation (single valve), 0,9 mm. This species may be distinguished from A. wrighti by the more elongate posterior end and the smoother surface.