Following examination of the type material, the three Diopsidae described by Dalman are redescribed. Diopsis apicalis belongs to a group of largely undescribed Diopsis with an apical wingspot. Its junior synonym is D. tenuipes Westwood. Diasemopsis (Diopsis) macrophthalma has never correctly been recorded again. It is neither conspecific, nor congeneric with the rice stem-borer Diopsis longicornis Macquart (= thoracica Westwood). The type series of Diasemopsis signata contained one macrophthalma. A lectotype is designated for signata, while four possible junior synonyms are indicated.