Bidentiseta (or Ephemera/fg5)

(Panephemeroptera Euephemeroptera Euplectoptera Anteritorna - Bidentiseta)

Nomen hierarchicum: Ephemera/fg5 [f:1810; g:1758] (sine Baetis; incl. Oligoneuria).

Nomen circumscribens: Bidentiseta Kluge 1993a: 41. 

In circumscription fits:

grex infraordines Bidentiseta: Kluge 1993a: 41

Bidentiseta = Ephemera/fg5: Kluge 2000: 248

References. Kluge 1993a: * 1998: *; Kluge 2004: *.

Autapomorphy of Bidentiseta.

(1) Maxilla has 2 dentisetae only distal and proximal ones [instead of initial 3 dentisetae see Anteritorna (2)]. In some specialized representatives of Bidentiseta further reduction of dentisetae takes place, thus only one (proximal) dentiseta can be retained, or dentisetae disappear at all (see Index of characters [1.1.37]). Among Bidentiseta more than two dentisetae nearly newer occur; an exception is made by Coloburiscus/fg1, where number of dentisetae is indeterminate and in specimens of the same species can be 2 or 3. Number of dentisetae less than three, besides Bidentiseta, is present also in some specialized taxa, which we attribute to Tridentiseta: specialized filtering maxilla of Ameletus/fg1 bears a single vestigial dentiseta, and specialized for carnivorism maxilla of Acanthametropus/fg2 bears two canine-like dentisetae. Thus, a formal number of dentisetae does not allow to divide all Anteritorna into Bidentiseta and Tridentiseta. The idea that Bidentiseta is a holophyletic taxon, is based on the fact that in each of evidently holophyletic taxa constituting the taxon Bidentiseta, the presence of two dentisetae is an initial condition: two dentisetae are present in many Eusetisura (Kluge 2004: Fig.44:D), Heptagennota (Kluge 2004: Fig.54:M, 58:F-H, 61:H, 65:F), Fimbriatotergaliae (Kluge 2004: Fig.68:C), Ephemerella/fg1 (Kluge 2004: Fig.92:B, 92:F,H, 93:D, 95:C, 96:C) and primitive representatives of Leptophlebia/fg1 (Kluge 2004: Fig.106:C,G). In many cases these maxillae with two dentisetae are non-specialized; hence, a conclusion can be made, that in common ancestor of Bidentiseta number of dentisetae was reduced to two, but maxillae remained to be non-specialized. Unlike Bidentiseta, in Tridentiseta number of dentisetae is reduced only in the cases when maxilla is strongly specialized as a whole. 

Character of Bidentiseta of unclear phylogenetic status.

(2) Possibly, ventral fibrillose portion on tergalii of Branchitergaliae and a bilamellate structure of tergalii in Furcatergaliae have common origin [see Branchitergaliae (3) and Furcatergaliae (4) below]. 

Size. Fore wing length 240 mm. 

Age and distribution. Late Jurassic (see Eusetisura INCERTAE SEDIS and Fossoriae INCERTAE SEDIS) Recent; world-wide.

The taxon Bidentiseta (or Ephemera/fg5) is divided into:

1. Branchitergaliae (or Heptagenia/f1=Oligoneuria/g1)

1.1. Eusetisura (or Oligoneuria/f1=g2)

1.1. 1. Coloburiscus/fg1

1.1. 2. Isonychia/fg1

1.1.3. Discoglossata (or Oligoneuria/f2=g3)

1.2. Heptagennota (or Heptagenia/f2=g1)
1.2.1. Pseudiron

1.2.2. Pentamerotarsata, or Heptagenia/f3=g2 Arthroplea Radulapalpata, or Heptagenia/f4=g3

2. Furcatergaliae (or Ephemera/fg6)

2.1. Fimbriatotergaliae

2.1.1. Potamanthus/fg1

2.1.2. Euthyplocia/fg1

2.1.3. Fossoriae, or Ephemera/fg8 Ichthybotus Ephemera/fg9 Behningia/fg1 Cryptoprosternata, or Palingenia/f1=Ephoron/g1

2.1.4. Caenotergaliae, or Caenis/f1=Brachycercus/g1 Neoephemera/fg1 Caenoptera, or Caenis/f2=Brachycercus/g2

2.2. Ephemerella/fg1

2.2.1. Ephemerella/fg2

2.2.2. Pantricorythi, or Tricorythus/fg1

2.3. Leptophlebia/fg1