Four new species of snakeflies of the family Inocelliidae: Inocellia longispina, I. bilobata, I. striata, and I. cornuta, spp. n. from Thailand are described and illustrated. A synthesis of the known species of Inocelliidae from Southeast Asia is presented. The questionable heuristic value of the classification of Inocellia, which advocates an I. fulvostigmata group and an I. crassicornis group, is discussed. The detection of four new partly syntopic species of Inocelliidae occurring within a small geographic range comes as a great surprise and infers that Southeast Asia is a hitherto unknown important evolutionary center of the family.