Figures: 93, 162, 233

In addition to the Heptageniinae characteristics, the following combination of characteristics will identify the genus:

Larval Diagnosis

The combination of submarginal anal ribs on the gill lamellae, vestigial gills 7, and minute gills 6 (Fig. 93) will differentiate Macdunnoa from all other Heptageniidae.

Adult Diagnosis

The combination of subquadrate penes and titillators that are thickened and abruptly narrowed apically (Fig. 162) will differentiate males of Macdunnoa from all other Heptageniinae genera. Females can be differentiated from those of other North American Heptageniiane by having eggs with a cresenct-shaped sperm guide and longitudinal grooves near the poles.


Nearctic (Fig. 233).