Belongs within: Pisciformia.
Contains: Pentamerotarsata.
The Heptageniomorpha are a group of mayflies in which the nymphs bear filamentous gills on the sides of the abdomen. They may be divided between the Heptagenioidea, in which the nymphs bear a frontal shield above the mouthparts, and the Oligoneurioidea, in which nymphs have a peculiar filtering specialisation of the fore legs and mouthparts (Kluge & Sinitshenkova 2002). The Oligoneuriinae are short-lived (even by the standards of mayflies) and have a strongly reduced wing venation (Kluge & Sinitshenkova 2002).
Synapomorphies (Kluge & Sinitshenkova 2002): Posterior arms of mesothoracic prealar bridge reduced in adults; eggs with anchors of peculiar structure; nymphal maxillae with ventral longitudinal row of setae; nymphal labial palp with segments 2 and 3 fused; nymphal tergaliae with gill filaments.
<==Heptageniomorpha [Branchitergaliae]
|--Heptagenioidea [Heptagennota]KS02
| |--PseudironKS02
| `--PentamerotarsataKS02
`--Oligoneurioidea [Eusetisura]KS02
|--IsonychiidaeKS02
| | i. s.: Siphlurus sanukensis Takahashi 1929TYM08
| |--RallidentinaeD70b
| `--IsonychiaD68 [IsonychiinaeD70b]
|--OligoneuriidaeKS02
| | i. s.: Colocrus indivicum McCafferty 1990RJ93
| | HomoeoneuriaR70
| | Oligoneuriella rhenana Imhoff 1852RD77, M86
| |--Chromarcys magnifica Navas 1932KS02, K03
| `--OligoneuriinaeKS02
`--Coloburiscidae [Coloburiscinae, Coloburiscini]KS02
|--Coloburiscus humeralisPC91, PC66
|--Murphyella needhamiD70b
|--Cronicus Eaton 1871D70a
| |--*C. anomalus (Pictet 1856) [=Baetis anomala; incl. B. longipes Hagen 1856]D68
| `--C. major Demoulin 1968D70a
`--ColoburiscoidesPC91
|--C. giganteusPC91
|--C. haleuticusPC91
`--C. muniongaPC91
*Type species of generic name indicated
References
[D68] Demoulin, G. 1968. Deuxième contribution à la connaissance des ephéméroptères de l’ambre oligocène de la Baltique. Deutsche Entomologische Zeitschrift (N. F.) 15 (1–3): 233–276.
[D70a] Demoulin, G. 1970a. Troisieme contribution a la connaisance des ephemeropteres d l’ambre Oligocene de la Baltique. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique 46 (2): 1–11.
[D70b] Demoulin, G. 1970b. Contribution a la connaisance de ephemeropteres du Miocene. I. Siphlurites explanatus Cockerell. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique 46 (5): 1–4.
[K03] Kluge, N. J. 2003. About evolution and homology of genital appendages of insects. Trudy Russkogo Entomologicheskogo Obshestva [Proceedings of the Russian Entomological Society] 74: 3–16.
[KS02] Kluge, N. Yu., & N. D. Sinitshenkova. 2002. Order Ephemerida Latreille, 1810. The true mayflies (=Ephemeroptera Hyatt et Arms, 1891 (s. l.); =Euephemeroptera Kluge, 2000. In: Rasnitsyn, A. P., & D. L. J. Quicke (eds) History of Insects pp. 89–97. Kluwer Academic Publishers: Dordrecht.
[M86] Marten, M. 1986. Drei für Deutschland neue und weitere, selten gefundene Eintagsfliegen aus der Fulda (Insecta, Ephemeroptera). Spixiana 9 (2): 169–173.
[PC66] Pendergrast, J. G., & D. R. Cowley. 1966. An Introduction to New Zealand Freshwater Insects. Collins: Auckland.
[PC91] Peters, W. L., & I. C. Campbell. 1991. Ephemeroptera (mayflies). In: CSIRO. The Insects of Australia: A textbook for students and research workers 2nd ed. vol. 1 pp. 279–293. Melbourne University Press: Carlton (Victoria).
[RD77] Richards, O. W., & R. G. Davies. 1977. Imms’ General Textbook of Entomology 10th ed. vol. 2. Classification and Biology. Chapman and Hall: London.
[R70] Riek, E. F. 1970. Ephemeroptera (mayflies). In: CSIRO. The Insects of Australia: A textbook for students and research workers pp. 224–240. Melbourne University Press.
[RJ93] Ross, A. J., & E. A. Jarzembowski. 1993. Arthropoda (Hexapoda; Insecta). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 363–426. Chapman & Hall: London.
[TYM08] Tennent, W. J., M. Yasuda & K. Morimoto. 2008. Lansania Journal of arachnology and zoology—a rare and obscure Japanese natural history journal. Archives of Natural History 35 (2): 252–280.