The diagnoses of all six tribes of Ulidiidae are revised. The Myennidini, new tribe (subfamily Otitinae), is defined to include 14 genera: Myennis Robineau-Desvoidy, Oedopa Loew, Stictomyia Bigot, Paroedopa Coquillett, Pseudotephritis Johnson, Callopistromyia Hendel, Stictoedopa Brטthes, Pseudotephritina Malloch, Dyscrasis Aldrich, Ulidiotites Steyskal, Pseudodyscrasis Hernández, Arborotites Barraclough, Namibotites Barraclough, and Neodyscrasis Kameneva and Korneyev, n. gen. (type species: Pseudodyscrasis steyskali Hernández, 1988). These genera were previously erroneously assigned either to the Ulidiini or to the Pterocallini; the latter tribe is shown here to belong to the subfamily Ulidiinae. A phylogenetic analysis is provided for the tribes of Ulidiidae and the genera of Myennidini. Most genera are redescribed, and the distributions of all the species are discussed, including new records. The following synonymy is established: Myennis tricolor Hendel, 1909 = Myennis nebulosa Krivosheina and Krivosheina, 1997, n. syn. Pterotaenia Rondani, 1868 is resurrected from synonymy with Ceroxys Macquart.