Landouria canalifera Páll-Gergely, Tumpeesuwan & Tumpeesuwan sp. nov. is described from Koh Samui, southern Thailand. It is characterized by a deep groove inside the umbilicus on the last ca. 1.5 whorls, corresponding with a columellar fold in the aperture. Also, there is a basal apertural tooth, corresponding with a shallow groove on the basal side of the shell just behind the peristome. These two barriers form a shallow canal in the aperture. Although the reproductive anatomy of this new species is not known, it probably belongs to the genus Landouria, which is widespread in Thailand and in the neighboring countries.