A new species: Daphniola louisi n. sp. from the spring at Kessariani, Athens, Greece, is described. This minute valvatoid-shelled snail is the second representative of the genus known so far. The shell, protoconch macro- and microsculpture, and radula are described and illustrated with SEM photographs. The other characters dealt with are: external morphology and soft part pigmentation, ctenidium and osphradium, penis, female reproductive organs. Differences between the newly described species and Daphniola exigua (A. Schmidt, 1856) are listed; phenetic relationships between the valvatoid-shelled Balkan hydrobiids are presented.