CLADOENDESIS OF EPHEMEROPTERA

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Characters of Oniscigaster/fg2 of unclear phylogenetic status.

(1) Larva is not operculate-gilled, in spite of the fact that tergalii I strongly differ from others [see Vetulata (1)]: tergalii I are not larger than others, not covering them; anal-proximal lobe of tergalii II–VI [see Vetulata (2)] is not bent dorsally, with incised margin (Kluge 2004: Fig.32:A). Taking into account that tergalii I are specialized, it can be assumed that operculate-gilled specialization disappeared secondarily.

Plesiomorphies of Oniscigaster/fg2. Imaginal and subimaginal paracercus is developed (but much shorter than cerci). On hind wing bifurcation of MP is nearer to base than to margin of wing, more proximal than bifurcations of RS and MA (unlike Tasmanophlebia/g1). Unlike Tasmanophlebia/g1, all tergalii I–VII are present [about tergalii I–VI – see (1), tergalii VII are vestigial].

Variable characters of Oniscigaster/fg2. In imago and subimago of both sexes projecting paranota can be developed on abdominal segments VII–IX (in wakefieldi [O.]), or on segments VIII–IX only (in intermedius [O.]), or are absent (in distans [O.]).