CLADOENDESIS OF EPHEMEROPTERA
Euephemeroptera,or Ephemeroptera sensu lato (or Ephemera/fg2)
(Panephemeroptera - Euephemeroptera)
Nomen hierarchicum: Ephemera/fg2 [f:1810; g:1758] (sine Triplosoba; incl. Phtharthus).
Nomina circumscribentia monosemantica:
Euephemeroptera Kluge 2000: 242
Reticulata Willmann 2006
Nomina circumscribentia non-monosemantica (in circumscription matching also Panephemeroptera and Euplectoptera):
Anisoptera Stephens 1835: 53 (s.l.)
Plectoptera Packard 1886: 808 (s.l.)
Ephemeroptera Hyatt & Arms 1891: 13 (s.l.)
Archipterygota Borner 1909: 121 (s.l.)
Prometabola Heymons 1909: 150 (s.l.)
Plectopteradelphia Crampton 1916: 305 (s.l.)
In circumscription monosemantically fits:
subordo Ephemerina: Tshernova 1980: 31
ordo Plectoptera: Handlirsch 1906: 37
ordo Ephemerida: Handlirsch 1919: 63 
ordo Ephemeroptera: Krausse & Wolff 1919: 157
Euephemeroptera = Ephemera/fg2: Kluge 2000: 242
In circumscription non-monosemantically fits (fitting also Panephemeroptera and Euplectoptera):
gen. Ephemera Linnaeus 1758: 546 (s.l.)
natio Ephemeraedes: Billberg 1820: 97 (s.l.)
tribus Ephemerides: Leach 1815: 137 (s.l.)
fam. Ephemerinae Latreille 1810: 273 (s.l.)
fam. Ephemerina: Burmeister 1829: 20 (s.l.)
fam. Ephemeridae: Stephens 1835: 54 (s.l.)
sectio Anisoptera Stephens 1835: 53 (s.l.)
subordo Ephemerina: Packard 1883: 192 (s.l.)
ordo Ephemerida: Haeckel 1866 (s.l.)
ordo Ephemeridae: Brauer 1885: 353 (s.l.)
ordo Plectoptera Packard 1886: 808 (s.l.)
ordo Ephemeroptera Hyatt & Arms 1891: 13 (s.l.)
ordo Agnatha: auct. (non Agnathes Cuvier 1798) (s.l.)
sectio Plectopteradelphia Crampton 1916: 305 (s.l.)
supersectio Archipterygota Borner 1909: 121 (s.l.)
cohors Prometabola Chen 1958 (s.l.)
References. Tshernova 1962b: *; Carpenter 1963: *; Kluge 2000: (L) *; Kluge & Sinitshenkova 2002: *; Kluge 2004: *.
Characters of Euephemeroptera of unclear phylogenetic status.
(1) Wings of both pairs have a costal brace a short vein, which goes from wing base between C and Sc, falls into Sc and at the same place is connected by a cross vein with RA. Unique character. For Protephemeroidea costal brace is not described. In known Permoplectoptera costal brace is situated between C and Sc (Kluge 2004: Fig.14:B), but in Euplectoptera it is stout, convex anteriorly, and projects dorsad-anteriad of C (Kluge 2004: Fig.6); only in Discoglossata it is modified (Kluge 2004: Fig.42:A).
(2) Vein RS arises not from RA, but from MA (unlike Protephemeroidea); the common basal stem RS+MA can be independent from RA (Kluge 2004: Fig.7:C), or basally fused with RA (particularly on hind wings of Euplectoptera Fig.7:D), or secondary reduced (Kluge 2004: Fig.17:A). Non-unique character, the same in some other Pterygota.
(3) Vein RSa2 [concave see Panephemeroptera (4)] forms a triad of concave RSa2' and RSa2'' and convex iRSa2 between them (Kluge 2004: Fig.7:C). Unique character. This third triad of RS is present on wings of both pairs in Permoplectoptera and fore wings of many Euplectoptera [but not on their hind wings see Euplectoptera (1) below]; on fore wings of some Euplectoptera veins RSa2' and iRSa2 secondarily become intercalaries or lost (see Index of characters [2.2.3839]).
(4) On wings of both pairs MA [convex see Panephemeroptera (3)] forms a triad of convex MA1 and MA2 and concave iMA between them (Kluge 2004: Fig.7:C-D). This branching of MA secondary disappears on vestigial hind winds of some Euplectoptera and on fore wings in some groups with especially modified venation (see Index of characters [2.2.43]). Usually furcation of MA is situated approximately in middle of wing, but sometimes it can be secondarily transferred proximally (on fore wings of some specialized Euplectoptera) or toward wing margin (on vestigial hind wings of some Euplectoptera).
(5) Larva is aquatic, with peculiar specialization for swimming (called siphlonuroid specialization) (Kluge 2004: Fig.9:A-B, 14:C-D, 28:A): abdomen is elongate and able to make undulate dorsoventral swimming movements; caudalii are not long (shorter than in imago), with primary swimming setae - i.e. each cercus has a row of setae on inner side, and paracercus has a pair of rows of setae of the same kind on its lateral sides; thanks to this, caudalii can function as a horizontal caudal flipper. As larvae of other Panephemeroptera are unknown, it is unclear if this specialization is an autapomorphy of Euephemeroptera or an autapomorphy of a larger taxon. In many Euplectoptera this swimming specialization is secondarily lost.
(6) Larva has tergalii on abdominal segments IIX (Kluge 2004: Fig.14:D). As larvae of other Panephemeroptera are unknown for certain, it is unclear, if the presence of tergalii is a character of Euephemeroptera or of a larger taxon; if proceed from the assumption that tergalii are serial homologues of wings, their presence is a plesiomorphy. In various Euephemeroptera tergalii of these or that pairs are lost (see Index of characters [1.3.2021]).
Size. Fore wing length 240 mm.
Age and distribution. Permian (see Permoplectoptera) Recent; world-wide.
|The taxon Euephemeroptera (or Ephemera/fg2) is divided into:|
1. Paleozoic plesiomorphon Permoplectoptera (or Protereisma/f1=Phtharthus/g1)
2. Mesozoic-Recent taxon Euplectoptera, or Ephemeroptera s.str. (or Ephemera/fg3)
Some fossil mayflies have uncertain systematic position see Euephemeroptera INCERTAE SEDIS