Both sexes of the new sp. are described and illustrated. Holotype <J, paratype 9: China, Wushishan, Hainan, 30-III-2008; deposited in the Collection of Aquatic Insects and Soil Animals, Department of Entomology, South China Agricultural University Guangzhou. T. hainanensis sp, n. is closely related to T. citimus (Needham), from which it can be distinguished by the labrum, colour of 6 superior appendices and by a pointed black occipital horn in 9.