Five species of Ascalaphidae were collected in the region of Pak-Chong in Central Thailand. Four of them are identified to specific level and are new for this country: Acheron trux, Ascalaphus prothoracicus, Ascalohybris oberthuri and Nousera gibba. Complementary information to the original descriptions is provided, and the gonarcus-paramere complexes are illustrated for the first time. Information on ecology of the species is provided.