The small reduviine genus, Tympanistocoris Miller, is revised. The type species of the genus, T. humilis Miller, is redescribed, and a new species, Tympanistocoris usingeri sp. nov., from Papua New Guinea is described. The illustrations of the antennae, head and pronotum, legs, hemelytra, abdomen, and male genitalia, as well as the habitus of the type specimens are also provided. The new species can be separated from the type species of the genus, T. humilis Miller, in the lateral sides of the pronotum with a distinct carina and the posterior margin of the seventh abdominal segment emarginated. The type specimen of the new species is kept in The Natural History Museum, London. The anastomosing veins of the hemelytra and the systematic position of the genus are briefly discussed.
Keywords: Papua New Guinea; Tympanistocoris; anastomosing veins; new species; taxonomy.