Shell with smoother sculpture, spiral cords often barely visible. One spiral row on shoulder and one or two rows at the periphery with very large open spines. Spiral cords sur-rounding umbilicus enlarged, forming a prominent ridge. Coloration usually more uniform than in typical argyrostoma; subspecies lajonkairii can attain a larger adult size (over 100 mm); often as tall as wide.

Known only from the eastern Indian Ocean; relatively common at Christmas Islands.