CLADOENDESIS OF EPHEMEROPTERA

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(1) Eggs have a peculiar structure, which distinguishes Ephemerythus from all other taxa (Kluge 2010: Fig.23; Kluge & Novikova 2017: Fig.21–24, 37–38, 78–84, 94–97; Kopelke 1980: Figs 38–42). Egg is elongate; one pole bears a polar cap, and egg is gradually narrowing toward opposite pole, which bears a tail. Polar cap is conic and has apical portion separated by a ring-form groove. Structure of tail is species-specific: it either represents an integral tube, or consists of 2–4 stout processes; these processes are connected by their bases and are narrowed toward apices, with apices pointed; the processes can be separated beginning from their bases, or fused one with another by means of thin walls; length of tail is species-specific. During development of the egg in a mature larva, the tail appears as a short protuberance and then increases in length. 

(2) Tergalii II are enlarged and serve as gill opercula, covering the rest tergalii (Kluge & Novikova 2017: Fig.11-13, 28-29, 39-41); they are unable to rhythmic respiratory movements; they can only press to the body (at rest) and rise up (to allow other tergalii to make fast rhythmic respiratory movements). Non-unique apomorphy (see Index of characters [1.3.39] and Table).

Tergalii II–V can retain bifurcate ventral lobe with processes [see Ephemerella/fg1 (7)], tergalii VI have no ventral lobe (Kluge 2010: Fig.10-14); sometimes tergalii V have no ventral lobe, sometimes tergalii VI are lost (Kluge & Novikova 2017: Fig.42-45, 90-93) [tergalii I and VII are always lost – see Tricoryptera (5) and (6)].

(3) On fore wing free marginal intercalaries are present, mainly 2 in each space (Kluge 2004: Fig.99:A) (as in many other Ephemerella/fg1 – see Index of characters [2.2.55]).

(4) Hind wing [of peculiar structure – see Tricoryptera (2)] has costal projection directed anteriorly-distally; Sc terminates at wing margin just distad of costal projection, its apex is connected with RA by a constant oblique crossvein (Kluge 2004: Fig.99:C). Non-unique character (see Index of characters [2.2.62] and [2.2.63]); it can not be compared with other Afrotricorythi, because their hind wings are always lost. In some species hind wings are present in both sexes (Kluge & Novikova 2017: Fig.58-67); in some species they are present in male and absent in female (Kluge 2010: Fig.1-5).

(5) In subimago, on all legs of male and female, 1st–4th tarsomeres are covered with microtrichiae (as are the tibiae); 5th tarsomere is covered with pointed microlepides (Kluge & Novikova 2017: Fig.68).

(6) In male larva caudalii (cerci and paracercus) are thickened in proximal part, unlike caudalii of female, which have usual form. In male imago (but not in subimago) caudalii are very long. The same in Tricorygnatha, Leptohyphes/fg1 and Caenoptera (Kluge 2004: Fig.103:E–F), unlike Machadorythus and Dicercomyzon.

Plesiomorphies of Ephemerythus. Unlike Tricorygnatha and Dicercomyzon, mouth apparatus is non-specialized, maxilla is biting [see Ephemerella/fg1 (16)], with 3 canines (ventral of them can be serrate) and 2 dentisetae [see Bidentiseta (1)].

In imago: Eyes of male are diminished, but slightly larger than in female (see Index of characters [2.1.3]). Mesonotum [see Ephemerella/fg1 (10)] retains curvation of lateroparapsidal suture and has no transverse interscutal suture (Kluge 2010: Fig.20) (unlike Tricorygnatha and some others – see Index of characters [2.2.9] and [2.2.10]); . Imaginal wing without setae on amphitornal margin (unlike Tricorygnatha and Leptohyphes/fg1). At rest, subimago and imago keep wings raised up (unlike Tricorygnatha and some others). All claws, including male fore leg, are ephemeropteroid.