Tripudia
Some species of Tripudia are said to be indistinguishable except by inspecting genitalia. T. quadrifera and T. rectangula are mostly able to be separated by range, with the former restricted to Texas, within the United States, and the latter found outside of Texas. It seems there are exceptions, though, and I think they can be fairly reliably distinguished as illustrated in these photos, marked up from photos at MPG.
In T. quadrifera the boundaries indicated with red lines are parallel. In T. rectangula they are further apart along the trailing edges of the wings.
