Three new species of Cochliopidae collected in a warm spring in Central Brazil in Chapada dos Veadeiros, Goiás, are described, based on conchological and anatomical features. One of them belong to the new genus Atomicus, characterized by the minute size (less than 1 mm), discoid shell, and other anatomical features; the type species is A. inopinatus n. sp. The other two species belong to the genus Heleobia: H. apua and H. pukua. All new species are so far only found in the type locality. The conchological, anatomical exclusivities and differences are explored under the context of other Brazilian and South American rissooideans/truncatelloideans