CLADOENDESIS OF EPHEMEROPTERA

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(1) On fore wing AA forms a fork which is either symmetric, or has an anterior branch arising forward from the main stem; no one branch arises backward from the main stem (Kluge 2004: Fig.68:A). In other mayflies AA is either non-branched or has one or several branches arising backward from the main stem (Kluge 2004: Fig.71:A, 81:A).

Apomorphies of Potamanthus/fg1 common with Caenotergaliae and Ephemerella/fg1 (see Classifications of Furcatergaliae I).

(2) In larva [which has collar on pronotum – see Fimbriatotergaliae (1)] mesonotum also has a collar – a concave band at anterior margin, separated from the rest part of mesonotum by a transverse crest (Kluge 2004: Fig.67:B–C). The same in Euthyplocia/fg1 and Caenotergaliae; the same mesonotal collar in Ephemerella/fg1.

(3) Dorsal (initially anterior) surface of larval fore femur can bear a transverse row of setae (as in Kluge 2004: Fig.89:H): regular row is present in some Rhoenanthus/g1, vestigial row – in selected specimens of Potamanthus/fg3 lutea [E.]; in other Potamanthus/fg2 this row is absent. The same in Caenotergaliae and Ephemerella/fg1 only.

(4) Tergalius I [different from others – see Fimbriatotergaliae (6)] is stick-like, setose, attached on a prominent cylindrical pedestal arisen from anterior part of the abdominal segment I close to metathorax (the same in Caenotergaliae and Ephemerella/fg1 only); pedestal is sclerotized (the same in Caenotergaliae); tergalius itself is subdivided to 2 segments (Kluge 2004: Fig.67:A) (the same occurs in Neoephemera/fg1).

(5) Egg with 2 polar caps and several (8–12) anchors; each anchor consists of a terminal knob and a skein of threads which surround the knob in a form of regular ring (Bae & McCafferty 1991: Fig.76–79). Similar caps and anchors are present in Ephemerella/fg1, and caps – also in some Caenotergaliae.

(6) In cubital field of fore wing [see Anteritorna (1)] several (2–5) veins go from CuA to basitornal and tornoapical margins; they are usually bifurcate (Kluge 2004: Fig.68:A: x, y), rarely simple. The same in Caenotergaliae and Ephemerella/fg1 (which initially have 1–3 bifurcate veins), as well as in selected specimens of Ichthybotus, Ephemera/fg9, and Pentagenia (which have 3–6 bifurcate or simple veins) and some others (see Index of characters [2.2.51]).

(7) Mandibular tusks [see Fimbriatotergaliae (8)] are curved medially. The same in Euthyplocia/fg1, Ichthybotus and Polymitarcys/f1=Ephoron/g2; probably symplesiomorphy.

(8) Maxilla [see Fimbriatotergaliae (10)] on apical-ventral side close to base of canines has a field of densely and regularly situated long setae (Kluge 2004: Fig.68:C; Elpers & Tomka 1994: Fig.4a-d). The same in Euthyplocia/fg1 and Ephemerella/fg1, and a similar field – in Leptophlebia/fg1 (see Index of characters [1.1.32]).

(9) In imago and subimago proximal part of gonostylus is integral, boundary between 1^st and 2^nd segments being non-expressed (the same in Euthyplocia/fg1 and some others). Both distal segments are always retained, thus gonostylus is 3-segmented.

Plesiomorphies of Potamanthus/fg1. In larva: Maxilla with 3 canines and 2 dentisetae [see Bidentiseta (1)] (Kluge 2004: Fig.68:C). Maxillary palp is 3-segmented; labial palp is 3-segmented (unlike Cryptoprosternata in Fossoriae). Larval (and adult) patella-tibial suture is developed on middle and hind legs only. Larva retains long abdomen able to make undulate swimming movements; caudalii with dense secondary swimming setae equally developed on lateral and median sides of cerci and lateral sides of paracercus [see Furcatergaliae (6)]. All tergalii I–VII [modified – see Fimbriatotergaliae (6)] are present; tergalii II–VII are spread by sides of abdomen, not bent dorsally (the same in Euthyplocia/fg1, unlike Fossoriae and Caenotergaliae).

In imago and subimago: Mesonotal suture is moderately stretched posteriorly, and subimaginal mesonotal cuticle has pigmented areas of characteristic shape [see Fimbriatotergaliae (2)] (Kluge 2004: Fig.68:F). Furcasternal protuberances are contiguous (Kluge 2004: Fig.68: D) (unlike Campsurus/fg1, Caenotergaliae and some others – see Index of characters [2.2.23]). Hind wing is well-developed, as long as 0.35–0.4 of fore wing length (Kluge 2004: Fig.68:B). Imaginal and subimaginal claws are ephemeropteroid (exception can be made by male imaginal fore legs only – see below).

Variable characters of Potamanthus/fg1. Eyes of male from large (as in majority of Ephemeroptera) to small as in female. In male imago on fore legs claws can be ephemeropteroid (in Rhoenanthus/g1 speciosus [Rh.]), more often both claws are blunt (while in subimago they are aways ephemeropteroid).