Two new species of terrestrial microsnails of the genus Hypselostoma W.H. Benson, 1856 (Gastropoda, Eupulmonata, Hypselostomatidae) from northeastern Thailand

Two new species of hypselostomatid land microsnails, <i>Hypselostoma pongrati</i> Tanmuangpak & S. Tumpeesuwan, <b>sp. nov.</b> from Nong Bua Lamphu Province and <i>H. sichomphuense</i> Tanmuangpak & S. Tumpeesuwan, <b>sp. nov.</b> from Khon Kaen Province, are described based on the morphology of their shell, radula, and genital system. Both new species are very similar in shell shape to <i>H. phupaman</i> from Chaiyaphum Province, possessing a double-keeled last whorl. However, <i>H. pongrati</i> Tanmuangpak & S. Tumpeesuwan, <b>sp. nov.</b> is distinguished by the absence of apertural barriers, whereas <i>H. sichomphuense</i> Tanmuangpak & S. Tumpeesuwan, <b>sp. nov.</b> possesses three apertural barriers, and <i>H. phupaman</i> possesses six or seven. The three species were found on isolated limestone hills in the Chaiyaphum-Khon Kaen-Nong Bua Lamphu-Loei area.