We made the acquaintance of mystery snails Cipangopaludina chinensis and C. japonica a couple of years ago. At the time, Dave Lawlor expressed the doubt that the two species were distinct.
Michelle Ryan, a doctoral student at George Mason, is trying to settle that question, as reported on page 8 of the current Marsh Wren from Friends of Dyke Marsh. She calls the genus Bellamya, but it’s the same critter. She’s recruiting volunteers to take measurements of snails found in the field.