Paracladura has a short m-cu crossvein between the discal cell and the forward branch of Cu. The other genera have the forward branch of Cu meeting the corner of the discal cell.
Diazosma has A2 long and sinous. The other genera have A2 short and curved.
Alexander, C. P. 1966. The Diptera or true flies of Connecticut. Part VI. First Fascicle. Connecticut State Geological and Natural History Survey, Bulletin 64: 1-509. (PDF)