Eight new species of marine dolichopodid flies from southern Thailand belonging to the genus Thinophilus Wahlberg, 1844 are described and illustrated: Thinophilus boonrotpongi sp. nov., T. langkawensis sp. nov., T. minutus sp. nov., T. parmatoides sp. nov., T. parvulus sp. nov., T. spinatus sp. nov., T. spinatoides sp. nov. and T. variabilis sp. nov. A key is provided to the species of the Thai-Malay Peninsula.
Marine Dolichopodidae, Thinophilus, peninsular Thailand.