(1) Hypopharynx is strongly shortened, twice shorter than superlinguae (Kluge 2004: Fig.56:E). In other Radulapalpata and majority of mayflies length of hypopharynx is subequal to that of superlinguae.

(2) Mouth apparatus is secondarily specialized as biting: mandibles are short and spout, maxillae are acute-angled with stout canines and dentisetae (Eaton 1883–1888: Pl.60:4–10). Non-unique apomorphy; among Radulapalpata the same in some Stenonema/fg1, Rhithrogena/fg3 and all Epeorus/fg3.

(3) Superlingua [curved laterally – see Heptagenia/f5=g4 (1)] with slightly concave lateral margin and angulate apex (Kluge 2004: Fig.56:E); by its form differs from any other taxon among Heptagenia/f5=g4.

(4) In imago and subimago 1^st tarsal segment is shortened, on fore tarsus of male several times shorter than 2^nd segment. Non-unique apomorphy (see Index of characters [2.2.76]); among Pentamerotarsata the same in Heptagenia/f8=g7, Raptoheptagenia and selected species of Kageronia, Ecdyonurus/fg1, Rhithrogena/fg3.

Plesiomorphies of Dacnogenia. Glossae are pyramidal [see Radulapalpata (1)], distal edge of glossa is not approximated to median edge (Kluge 2004: Fig.56:F-G) (unlike Heptagenia/f8=g7, Stenonema/fg1 and Ecdyonurus/fg1). All tergalii I–VII with fibrillose portion.