The Thai fauna of eleven agathidine genera, i.e., Biroia, Braunsia, Camptothlipsis, Coccygidium, Cremnops, Cremnoptoides, Disophrys, Earinus, Gyrochus, Lytopylus, and Troticus, are revised. 25 species are treated, 20 of which are found in Thailand and five that are likely to occur there. Six new species are described, i.e., Braunsia chaweewanae, Camptothlipsis annemariae, Camptothlipsis sheilae, Coccygidium mastigion, Coccygidium phaeoscapos, and Cremnoptoides yui. The following new synonomies are proposed: Isopronotum seminigripenne Enderlein, Isopronotum seminigripenne Enderlein, Isoptronotum seminigripenne rufescens, Enderlein Isopronotum tricolor Enderlein, Biroia soror Achterberg and Long, are all synonymized with Biroia fuscicornis (Cameron 1903). Braunsia pumatica van Achterberg and Long is synonymized with Braunsia fumipennis (Cameron 1899). Braunsia devriesi van Achterberg and Long is synonymized with Braunsia smithii (Dalla Torre 1898). Cremnops malayensis Bhat and Agathis nigritarsus Cameron 1899 are synonymized with Cremnops desertor (Linneaus 1758). Disophrys macilifera van Achterberg and Long is synonymized with Disophrys strigata Enderlein 1920. Disophrys guymanhi van Achterberg and Long is synonymized with Disophrys subfaciata (Brullé, 1846). Agathis burmensis (Bhat & Gupta, 1977) is synonymized with Lytophylus ebulus (Nixon 1950). Disophrys ornatipennis Cameron 1905 is transferred to Gyrochus ornatipennis (Cameron 1905) n. comb. Agathis flavipennis Brullé is transferred to Gyrochus flavipennis (Brullé 1846) n. comb. Troticus melanopterous Cameron is removed from the genus Cremnops and reinstated in Troticus. Keys to the genera of Thai Agathidinae and keys to the species of each genus with multiple species are presented.
