(1) In larva lateral flat projections of pronotum [which are more or less developed in all Heptagennota, that is connected with body flattening – see Heptagennota (1)] are large, partly fused with lateral margins of mesonotum and continued posteriorly as a pair of projections situated laterad of mesonotum (Kluge 2004: Fig.57:I). Non-unique apomorphy: various posterolateral projections of pronotum independently appeared in other mayflies.

Plesiomorphies of Ecdyonurus/fg2. Distal dentiseta is simple (Kluge 2004: Fig.58:F), or distally bifurcate [like proximal dentiseta – see Ecdyonurus/fg1 (2)] (unlike Atopopus/fg1). Primary swimming setae [vestigial – see Pentamerotarsata (6)] are present. Median titillators of penis are well-developed, contiguous medially (unlike Afronurus/g1).

Variable characters of Ecdyonurus/fg2. In male imago 1^st segment of fore tarsus can be relatively long (longer than 1/2 of 2^nd segment) or short (several times shorter than 2^nd segment, like in Heptagenia/f8=g7 and some others).