CLADOENDESIS OF EPHEMEROPTERA

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Autapomorphy of Chromarcys.

(1) Larval, subimaginal and imaginal paracercus is diminished, several times shorter than cerci (but not vestigial, several times longer than 10th abdominal segment) (Ulmer 1939: Fig.390; Demoulin 1967a: Fig.1d). Non-unique apomorphy (see Index of characters [2.3.22]).

Plesiomorphies of Chromarcys (unlike Geminovenata). All tergalii, including pair I, are attached dorsally and have the same structure [see Discoglossata (1)]. In imago and subimago: Mesonotal suture is normally developed, nearly transverse, not shifted posteriorly; separate sclerite forming posterior half of medioscutum is present in subimago only (Kluge 2004: Fig.42:D), while in imago the whole medioscutum is evenly sclerotized. Anterior paracoxal suture is not curved posteriorly. Middle and hind legs are functional, with ephemeropteroid claws (Kluge 2004: Fig.42:G). Wings with many intercalaries and crossveins; number of intercalaries, unlike Geminovenata, is not only non-reduced, but even increased if compare with other mayflies: additional intercalaries are present in widened field between MP₁ and MP₂ (Kluge 2004: Fig.42:A-B). Pedestals of gonostyli are large, with well-developed muscles (as in Isonychia/fg1 and Coloburiscus/fg1); border between 1^st and 2^nd segments of gonostyli is retained; penis has simple structure (Kluge 2004: Fig.42:C). Cerci are not soft, segmented, with irregular setae (Demoulin 1967a: Fig.1d) (unlike many Geminovenata).

Variable character of Chromarcys. On hind wing bifurcation of MA is shifted distally (Kluge 2004: Fig.42:B) or lost (Demoulin 1953a: Fig.1b; 1967a: Fig.1b) (it is lost also in Geminovenata; probably synapomorphy).