CLADOENDESIS OF EPHEMEROPTERA

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(1) Larval body and legs are greatly modified in such a manner that allow larva to push itself through sand not burrowing it [see Behningia/fg1 (1)] (Kluge 2004: Fig.73:A–D):

Segments of thorax and abdomen, except for posteriormost abdominal segments, are shortened and widened. Pronotum, besides the pair of flat anterolateral projections covered with setae [see Behningia/fg1 (1)], with a pair of flat bald posterolateral projections.

On all legs claws are lost. Fore legs [initially burrowing – see Fossoriae (1)] are diminished, palp-like.

Middle and hind legs are modified in such a manner, that tibia and tarsus of middle leg and femur of hind leg are directed by their apices posteriorly, widened, covered with setae and are used for pushing through sand.

On middle leg femur [whose initial posterior side is external, convex and setose – see Fossoriae (1)] is shortened, on outer side bears stout setae directed posteriorly; tibia is shortened and strongly widened, with large apical projection inward from tarsus (but at the same time there is retained a patella-tibial suture in a form of long arc on wide flat bare inner side of the tibia); tarsus is wide, narrowed toward apex, curved by its convexity outwards; on the side directed outwards (corresponding to posterior or ventral side of non-specialized leg) tibia and tarsus are densely covered with stout setae directed posteriorly.

Hind leg has coxa enlarged, movable; femur more or less widened; tibia very strongly diminished; tarsus strongly elongate, straight.

The same proportions of leg segments are retained in vestigial legs of subimago [see Behningia/fg1 (3)].

Tergalii are transferred to ventral side because the paired longitudinal ridges bearing setae [see Behningia/fg1 (1)] at least on abdominal segments III–VII are strongly expanded laterally covering tergalii from above (in Dolania such distinct lateral projections are present on abdominal segments III-VII, in Behningia/fg3 – on segments III–IX).

(2) Mouth apparatus [carnovorous – see Behningia/fg1 (2)] is gratly modified (Keffermuller 1959: Pl.VII; Edmunds & Traver 1959: Fig.8–22; Elpers & Tomka 1994b: Fig.8–21): Maxilla is diminished, with a single slender canine (instead of three initial canines and two canines in Protobehnongia) (the same in Palingenia/f2=g1 and some others – see Index of characters [1.1.33]). Maxillary palp [3-segmented – see Plesiomorphies of Behningia/fg1] is gratly enlarged, 1^st segment of palp is much thicker than maxilla, sharply widened just from place of its attachment; flexor and extensor of 2^nd segment (situated in the 1^st segment) are strongly thickened, being proximally attached to widened base of 1^st segment, correspondingly inward and outward from place of attachment of 1^st segment.

Labium is diminished, glossae and paraglossae are markedly shortened, labial palp [3-segmented – see Plesiomorphies of Behningia/fg1] is greatly enlarged; flexor of 2^nd segment (situated in 1^st segment) is greatly thickened, fan-form, proximally attached not only to base of 1^st segment, but also to its inner side.

(3) Cubital field of fore wing [see Anteritorna (1)] includes a strong convex vein ("CuA₂") arising from CuA to basitornal margin and looking as a branch of CuA; one or several intercalaries [see Behningia/fg1 (6)] are situated between "CuA₂" and the distal part of CuA (Edmunds & Traver 1959: Fig.24,31). The same in some other short-living mayflies – Geminovenata and certain Anagenesia/g1 (see Index of characters [2.2.51]).

(4) Gonostylus [which has no distal segments – see Behningia/fg1 (10)] is 1-segmented, because proximal segment is not expressed. Non-unique apomorphy (see Index of characters [2.3.10]).

Plesiomorphies of Behningia/fg2 (unlike Protobehningia). On maxilla [see (2)] dentisetae are retained (but can be slender and hardly distinguishable among setae): Behningia/fg3 has both dentisetae [see Bidentiseta (1)], Dolania – a single proximal dentiseta only (Elpers & Tomka 1994b: Fig.15b). Larval tarsus of fore leg is not fused with tibia.