CLADOENDESIS OF EPHEMEROPTERA

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(1) Gill operculum [i.e. tergalius II – see Caenotergaliae (1)] has unique structure (Kluge 2004: Fig.82:A,D). Its margin directed medially (initial anal margin of tergalius) is bent ventrally; along its line of bend goes a sclerotized crest, which bears dense setae directed medially or obliquely; the bent portion is membranous and directed ventrally, perpendicular to the rest portion of gill operculum. Left and right opercula are connected mesially by their lines of bend and firmly coupled by setae.

(2) Larval abdominal terga VI–VIII with more or less expressed unpaired projection on posterior margin [besides projection on tergum II – see Caenotergaliae (1)]. Non-unique apomorphy (see Index of characters [1.3.3]).

Plesiomorphies of Neoephemera/fg1. In larva: Maxillary palp is 3-segmented (unlike Brachycercus/f1=g3 and Clypeocaenis/g2). Labial palp is 3-segmented (unlike Brachycercus/f1=g3). Tergalii II–V [see Caenotergaliae (1)] retain vestigial ventral lamella with marginal processes (Kluge 2004: Fig.82:D–E) (unlike Caenoptera).

In imago and subimago (unlike Caenoptera): Eyes of male are larger than in female and retain division to dorsal and ventral portions. Thorax has no modifications peculiar for Caenoptera (Kluge 2004: Fig.83:A–F). Mesonotal suture is well-expressed both in subimago and imago, being strongly stretched posteriorly by sides of median line [see Fimbriatotergaliae (2)], and has a characteristic uniform structure in all representatives: its median components represent distinct grooves going longitudinally between the medain longitudinal suture and medioparapsidal sutures (Kluge 2004: Fig.83:E). Subimago is not shortly-moulting; subimaginal cuticle retains characteristic colour pattern [see Fimbriatotergaliae (2)–(4)] (Kluge 2004: Fig.83:C,F). Fore wing has curved MP₂ and CuA [see Fimbriatotergaliae (5)], large number of cross veins and connected or free marginal intercalaries; cubital field with variable number (1–3) of bifurcate and/or simple veins arising from CuA to wing margin [see Caenotergaliae (9)]; hind wing is well-developed, as long as 0.3–0.4 of fore wing length. Tarsus retains structure initial for Furcatergaliae: first segment is short, usually fused with tibia (Kluge 2004: Fig.83:G); only in Ochernova first tarsal segment is secondarily separated from tibia (Kluge 2004: Fig.81:C). Gonostylus is usually 4-segmented: with 2 short distal segments and usually (except for Potamanthellus/g1) with elongate 1^st segment separated by a ledge from 2^nd segment (Kluge 2004: Fig.81:D, 82:H).