Two new species of Landouria Godwin-Austen, 1918 (Gastropoda, Camaenidae) from Thailand, with a key to Thai species

The present work contains descriptions of two new species of <i>Landouria</i> and a key to Thai species of this genus. <i>Landouriabella</i> <b>sp. nov.</b> is described from isolated limestone hills in Ratchaburi and Phetchaburi provinces, western Thailand. This new species is characterized by its small depressed-globose shell without a peripheral keel, the presence of a small, thin lamella on the columellar side of the inner aperture, a long, cylindrical distally bent flagellum, a short penis with a rounded verge, and a short, thick free oviduct and vagina. The second new species, <i>Landouriamonodon</i> <b>sp. nov.</b> is described from sandstone hills in Kalasin Province, northeastern Thailand. This species has a depressed-conic shell with a blunt peripheral keel, a thick prominent lamella on the columellar side of the inner aperture, a short, finger-shaped, distally bent flagellum, and a long penis with a small, short verge.