ABSTRACT. Rare European species Pupilla pratensis

is registered in the same calcareous fen in the Crimean Mountains, where Vertigo moulinsiana, another rare European species, was found earlier. Both species are known in Ukraine only from this small site (less than 0.01 km2), which is disturbed and not protected, there-fore both species are clearly “Critically Endangered” here. In the materials of Pupilla muscorum from Ukraine some unusually large specimens with shell width 1.9-2.0 mm were revealed. Therefore P. pratensis and P. muscorum can’t be distinguished by this character alone, as it was sometimes considered before. The Crimean Mountains are a small mountain system located parallel to the Black Sea coast in the south of the Crimean Peninsula (southern Ukraine). Their extension is about 160 km and width is up to 50 km, highest point – 1545 m (Roman-Kosh Moun-tain). Terrestrial molluscs of the Crimean Moun-tains were studied in details as early as the late nineteenth century – beginning of the twentieth century, when most known now species were re-corded. But each mountain system contains very diverse habitat conditions, and some invertebrate populations can exist in a very restricted area. There-fore new species still can be found in Crimea. In this way probably native species such as Vertigo moulinsiana (Dupuy 1849), Deroceras subagrest