A new species, Balcanodiscus (Balcanodiscus) danyii n. sp. is described from the Sapka Mountains in Thrakia (northeastern Greece). B. danyii seems to be the smallest species of the Balkan endemic genus Balcanodiscus Riedel & Urbanski 1964. According to anatomical data, its closest related species is Balcanodiscus cerberus Riedel 1984. A comprehensive table is presented to summarize the main anatomical and shell characters of known Balcanodiscus species.