(Panephemeroptera Euephemeroptera Euplectoptera Anteritorna Bidentiseta Branchitergaliae
Heptagennota Pentamerotarsata Radulapalpata - Heptagenia/f5=g4)

Nomen hierarchicum: Heptagenia/f5=g4 [f:1901; g:1863] (sine Raptoheptagenia, Cinygma, Rhithrogena; incl. Ecdyonurus).

In circumscription fits:

 tribus Heptageniini: Kluge 1988: 292

 Heptagenia/f5=g4: Kluge 2004: 166

References. Kluge 1988: *; Tomka & Elpers 1991: *; Kluge 1993: * *; 2004: * * * *.

Characters of Heptagenia/f5=g4 of unclear phylogenetic status. 

(1) Superlinguae are curved laterally. This feature is present in all Heptagenia/f5=g4, but shape of superlinguae differs in different groups (Kluge 2004: Fig.54:B, 55:F, 56:E,H, 58:D). Non-unique apomorphy; among Heptagennota superlinguae are curved laterally also in Arthroplea, but have different shape.

(2) Larval caudalii with whorls of stout setae on posterior margin of each segment. By this character Heptagenia/f5=g4 differs from other Heptagennota; the same in many other mayflies.

(3) Abdominal ganglia VII and VIII are brought together. Non-unique apomorphy; the same in Arthroplea and some others, but not in Rhithrogena/fg1, where distance between these ganglia is much larger.

Plesiomorphies of Heptagenia/f5=g4. Unlike Cinygma, all 3 maxillary canines are retained (while often being weak Kluge 2004: Fig.54:M, 58:F,H). Maxillary palp is not so specialized as in Rhithrogena/fg1, with a vestige of 3rd segment (Kluge 2004: Fig.55:H, 58:E). Labial palp has no bifurcate setae (Kluge 2004: Fig.57:G) (unlike Rhithrogena/fg1). Tergalii retain ability of rhythmical respiratory movements (Kluge 2004: Fig.57:C-E) (unlike Cinygma and Rhithrogena/fg1) [for comment see Rhithrogena/fg1 (6) below] (see Index of characters [1.3.30]). Lateroparapsidal sutures are not curved laterally, terminate near medioparapsidal sutures (unlike Rhithrogena/fg1); subimaginal lateroparapsidal stripe of pigmented area of mesonotum [see Heptagennota (2)] is widened posteriorly (Kluge 2004: Fig.54:I) (unlike Rhithrogena/fg2 and Epeorus/fg1). As an exception, lateroparapsidal sutures can be curved laterally (in Stenonema/fg2 terminata [Palingenia]), but in this case they are shorter than in Rhithrogena/fg1, and do not reach bases of posterior scuto-coxal muscles (S.CmP) (Kluge 1988: Fig.89:TCxm4). Larval and adult patella-tibial suture is developed on middle and hind legs only (unlike larval Rhithrogena/fg3).

Size. Fore wing length 518 mm.

Age and distribution. Palaeogene (see Kageronia) recent; Arctogea (Holarctic + Oriental + Afrotropical Regions) and Central America; dominate in Holarctic.

The taxon Heptagenia/f5=g4 is divided into:

1. Heptagenia/f6=g5

1.1. Kageronia

1.2. Heptagenia/f7=g6

1.2.1. Heptagenia/f8=g7

1.2.2. Dacnogenia

1.2.3. Stenonema/fg1

2. Ecdyonurus/fg1

2.1. Ecdyonurus/fg2

2.2. Leucrocuta/f1=Afghanurus/g1

2.3. Atopopus/fg1