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Unsure of genus. Collected Groton, Massachusetts on 5 x 2012.

In Manual of Nearctic Diptera, this runs to Sciophilinae (coupl. 25). Not sure about wing micro/macrotrichae (coupl. 28), but going to 29 takes me to Paratinia. Going to 47 takes me to either Tetragoneura (which includes Ectrepesthoneura) or Dziedzickia.
Manual of Central American Diptera leads me to either Undescribed genus B or Dziedzickia.

I feel like I'm way off...

Laterotergite bare.
Mediotergite bare.
R2+3 present.
Sc ends in R.
C extends well past apex of R4+5.
Tibial setae not in rows.
Body length ~3.7 mm