The shape of adult mouthparts (proboscis) of all genera of Hyadinini (Diptera: Ephydridae) is provided, including variability of cibarium, lacinia and the number of pseudotracheae. Its usage in phylogenetic construction is documented. All ten genera are diagnosed, including the genus Lytogaster, which is formally restored from synonymy with Hyadina. The ventral receptacle of four genera (Garifuna, Parahyadina, Parydroptera and Pelinoides) and the male terminalia of Parahyadina are presented for the first time. Monophyly of the tribe is discussed and the relationships among genera of Hyadinini are proposed. Ten Hyadinini genera are grouped into four lineages 1) Pelina group with Pelina and Parydroptera, 2) Pelinoides group with Pelinoides, 3) Philygria group with Nostima and Philygria, 4) Hyadina group with Axysta, Lytogaster, Hyadina, Parahyadina and Garifuna.