CLADOENDESIS OF EPHEMEROPTERA

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Character of Iron/g1 of unclear phylogenetic status. 

(1) Tergalii [see Epeorus/fg3 (2)] form an adhesive disk, resembling sucking disk of Rhithrogena/fg3 [with this is connected the name "Iron", which means "a dissembler" (Eaton 1883–1888: 245)]: tergalius I [which has costal rib at a distance from costal margin – see Epeorus/fg2 (1)] is more or less widened anteriorly and turned under thorax, thus apices of left and right tergalii I are brought together or contiguous; tergalius VII has a sharp longitudinal fold, because of which it is bent ventrally under last abdominal segments (Kluge 2004: Fig.65:B). Unlike Rhithrogena/fg3, the tergalial disc of Iron/g1 does not function as true sucker, because its margins are rigid and armed with hook-like setae [see Epeorus/fg2 (2)]. The anterior widening of tergalius I can be widened distally (like in Rhithrogena/fg3) or narrowed distally, sometimes it can be expressed as poorly as in Epeorus/fg4; the fold of tergalius I is always expressed. It can be assumed that the tergalial disk appeared as a convergention in several non-related groups of Epeorus/fg3 (in the same manner as it appeared independently in Rhithrogena/fg3), because no other apomorphies of Iron/g1 are known.

Plesiomorphy of Iron/g1. Unlike Belovius/g1, tergalii II–VII have anal rib on anal margin.