A new species, Cassida alidagiense sp. nov., has been described from Kayseri province in Turkey. For the time being, the species is endemic to Turkey. Cassida alidagiense sp. nov., is related to Cassida linnavuorii Borowiec, 1986; Cassida brevis Weise, 1884; and Cassida bella Faldermann, 1837, from which it differs in the shape of the apex of cornu of the spermethaca, and it can be distinctively differentiated from these species based on color of under body and spermathecal characters especially. In addition, the paper presents ultrastructures observed by SEM of spermatheca of Cassida alidagiense sp. nov. from Turkey.