(1) Larva [flattened – see Heptagennota (1)] has very wide head and relatively short legs; head shield is so sharply expanded laterally, that behind it head margin forms a pair of postero-lateral emarginations (Kluge 2004: Fig.59:A). In other Heptagennota such emarginations are either absent, or shallower.

(2) Dorsal lamella of tergalius I [curved dorsally – see Ecdyonurus/fg1 (3) is vestigial, much smaller than ventral fibrillose lobe [see Ecdyonurus/fg1 (6)]. Non-unique apomorphy.

(3) Wings with characteristic brown pigmentation: on fore wing at distal part of costal area, at subcostal area and close to hind margin at cubital area; on hind wing close to margin at distal half. Non-unique character: the same in some Oriental species of Heptagenia/f6=g5.

Plesiomorphies of Atopopus/fg2. Unlike Afronurus/g1 and Electrogena, penis [see Pentamerotarsata (5)] has contiguous median titillators and distinct ventral and outer sclerites with laterodorsal spines (at least in tarsalis [A.]) (Kluge 2004: Fig.59:B-C).