Hydatostega is a genus of flies in the family Dolichopodidae. Most of its species are found in the Americas, where it is mainly restricted to montane habitats and high altitudes or latitudes, while three species are known from Tristan da Cunha, a group of islands in the South Atlantic Ocean. Hydatostega was formerly considered a synonym of Hydrophorus, but was recently restored as a separate genus.

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