Subgenus Ephydra Fallén

See generic synonymy.

Diagnosis. The subgenus Ephydra is distinguished from other subcongeners by the following combination of characters:

Head: Cruciate, interfrontal setae 1 pair, well developed.

Thorax: Coloration of mesonotum generally shiny, at least partially; crossvein dm-cu merged with vein CuA1 at nearly right angle.

Abdomen: Male terminalia with surstyli relatively stout and distally blunt; gonite bearing 2 very characteristically placed, subapical setae; aedeagus swollen at base or with strongly recurved basal process.

Distribution. See generic treatment.

Remarks. This subgenus comprises all species of Ephydra except E. gracilis, the only species of the subgenus Halephydra. All species of the Western Hemisphere belong to either of two species groups: the glauca and riparia groups. Both groups are represented by a single species in the geographic area being treated.