CLADOENDESIS OF EPHEMEROPTERA

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(1) Tergalial ventral lobe [initially bifurcate and bearing processes – see Ephemerella/fg1 (7)] is modified in a following manner. It lost initial numerous marginal processes and bifurcates from base, thus two its branches (costal and anal ones) represent two separate lamellae these branches can either lack processes at all (in Allenhyphes, Tricorythodes), or have a few lamellate processes arising basally from ventral side (tergalii III-V of Leptohyphes/fg2 and Tricorythopsis – Kluge 2004: Fig.101:D–I), or have by one marginal process on each branch (tergalius II of Tricorythopsis). Probably initially for Leptohyphes/fg1, costal branch is widened and projects from under costal margin of dorsal lobe (Kluge 2004: Fig.101:F–H) (while in other Ephemerella/fg1 both branches are usually completely covered by dorsal lobe); this is connected with a peculiar construction of operculate tergalius II.

Tergalius II has dorsal lobe transformed to a gill operculum, which covers the rest tergalii [III–VI – see Tricoryptera (5) and (6)] (non-unique apomorphy – see Index of characters [1.3.32] and Table). Its costal branch of ventral lobe is bent longitudinally so that its portion projected from under dorsal lobe, orientates perpendicular to the flatness of the rest tergalius (Kluge 2004: Fig.103:A–B); this portion of costal branch can be called costal flap. Dorsal lobe and costal flap together form a gill chamber enclosing respiratory tergalii III-VI of one side: dorsal lobe limits this gill chamber dorsally, and costal flap limits it laterally. In the group sacculobranchis costal flap is elongate, apically curved and closes gill chamber not only laterally, but posteriorly as well (Kluge 2004: Fig.103:D). Tergalii-bearing abdominal segments III-VI have especially wide and flat paranota laterad of tergalii bases; when tergalius II is pressed to the body, costal margin of its dorsal lobe touches lateral margins of paranota, and costal flap appears to be hidden (Kluge 2004: Fig.103:D). Such opercula structure is present in Allenhyphes and Tricorythodes; in Leptohyphes/fg2 costal flap is reduced to a spine-like basal vestige (Kluge 2004: Fig.101:D); only in Tricorythopsis costal flap is absent [see Tricorythopsis (8) below].

Tergalii III–V have following peculiarity. Costal rib is lost, thus dorsal lobe has only anal rib in a form of thin sclerotized arched line [at a distance from anal margin – see Fimbriatotergaliae (6)] (unlike tergalius II, which can have both costal and anal ribs developed). The projected portion of costal branch lies in the same flatness as the whole tergalius and sometimes can bear a thin additional rib resembling lost costal rib of dorsal lobe (Kluge 2004: Fig.103:C). Tergalius VI (the last one) has simplified structure.

In some species of Leptohyphes/fg1 certain tergalii lost anal branch or entire ventral lobe.

(2) Hind wing, if present, has unique structure (Kluge 2004: Fig.100:B): costal projection [pointed – see Tricoryptera (2)] is extremely shifted to wing base and arises perpendicular to the main wing axis; this projection is very long, slender and often arched at proximal direction. Sc is short, curved anteriorly and terminates close to base of the costal projection; sometimes Sc is lost. The rest part of wing is narrow, with 1–3 non-branched veins. In spite of the peculiar form of hind wing in imago and subimago, larval hind protopteron retains a usual form, being wide, without prominent costal projection (Kluge 2004: Fig.100: C–D), like in Ephemerella/fg2 and other mayflies with normal hind wings (hind protoptera are examined only for eximius [L.], zalope [L.] and flinti [L.], where they are present in males only).

Hind wings are present in both sexes of Haplohyphes; more often (in Leptohyphes/fg2, Allenhyphes, Vacupernius, Yaurina, Traverhyphes) hind wings are present in males only.

In Tricorythodes, Tricorythopsis and some others hind wings are lost in both sexes.

It is not quite clear if the peculiar hind wing structure is an autapomorphy of Leptohyphes/fg1, because in many other Tricoryptera hind wings are lost (see Index of characters [2.2.59]), and their initial structure in unknown.

Characters of Leptohyphes/fg1 of unclear phylogenetic status (including apomorphies common with Tricorygnatha and Caenoptera – see Classifications of Furcatergaliae II).

(3) Eyes of male are usually as small as in female (non-unique apomorphy – see Index of characters [2.1.3]); only in Tricorythodes/fg1-Homoleptohyphes male eyes are enlarged, probably secondarily.

(4) Imaginal and subimaginal mesothorax [see Tricoryptera (3)–(4)] has following modifications common with Tricorygnatha and Caenoptera: In subimago cuticular pigmentation is lost (Kluge 2004: Fig.104:I). Sublateroscutum has a transverse interscutal suture. Lateroparapsidal suture is not so strongly curved laterally as is initial for Ephemerella/fg1; some curvation is retained in Leptohyphes/fg2 and Allenhyphes, where lateroparapsidal suture merges with the transverse interscutal suture laterad of medioparapsidal suture (Kluge 2004: Fig.102:A); in Tricorythodes lateroparapsidal suture is more straightened and merges with transverse interscutal suture posteriad of its merging with medioparapsidal suture (Kluge 2004: Fig.104:A). Anterior paracoxal suture is transferred posteriorly, nearer to anterior margin of coxal conjunctiva (Kluge 2004: Fig.102:B, 104:B).

(5) On fore wing marginal intercalaries are absent (Kluge 2004: Fig.100:A). Among Ephemerella/fg1 the same in Dicercomyzon and Tricorygnatha (see Index of characters [2.2.55]); the same in Caenoptera.

(6) In imago amphitornal margin of wing with setae (as in subimago of all mayflies) (Kluge 2004: Fig.66:C; 100:A–B). Non-unique apomorphy (see Index of characters [2.2.27]); particularly, the same in Tricorygnatha and Caenoptera; probably synapomorphy.

(7) On fore leg of male imago both claws are blunt, in subimago ephemeropteroid (Kluge & Naranjo 1990: Fig.33–36). Non-unique apomorphy (see Index of characters [2.2.77]). Other claws are ephemeropteroid (see Plesiomorphies of Ephemerella/fg1). Fore some species ephemeropteroid imaginal fore claws were reported; in these cases subimagoes were taken for imagoes (Molineri & Peters & Zuniga-de-Cardoso 2001: 118).

(8) In male larva caudalii [cerci and paracercus – see Plesiomorphies of Ephemerella/fg1] are thickened at proximal part, unlike caudalii of female, which have usual form (Kluge 2004: Fig.103:E-F). In male imago (but not in subimago) caudalii are very long. The same in Tricorygnatha, Ephemerythus and Caenoptera. In female imago and subimago caudalii can be either normally developed, or diminished [see Tricorythodes (6) below].

(9) Adults are shortly-moulting: in mature larva ready to moult to subimago, imaginal cuticle is already developed; shortly (in a few minutes) after the moult from larva to subimago, the next moult from subimago to imago follows. At the same time, imagoes are not short-living, and have functional legs. Subimaginal cuticle has no distinct pigmented and sclerotized areas characteristic for many other mayflies [see Ephemerella/fg1 (10)]. Besides Leptohyphes/fg1, adults are shortly-moulting and non-short-living in Tricorygnatha and Caenoptera.

(10) At rest, subimago and imago keep wings spread by sides or somewhat turned up (unlike Dicercomyzon and Ephemerythus, whose wings are raised up, as in most mayflies). Among maylies with functional legs, the same in Tricorygnatha, Caenoptera and a few others; the same in short-living mayflies.

Plesiomorphy of Leptohyphes/fg1. On fore wing CuP is more or less strongly arched by its convexity anteriorly and by apex posteriorly, thus the bifurcate vein iCu, which arises from it anteriorly [see Tricoryptera (1)], does not form symmetrical fork with CuP (Kluge 2004: Fig.100:A) (unlike Afrotricorythi).