CLADOENDESIS OF EPHEMEROPTERA

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Autapomorphies of Rallidens.

(1) Mandible is elongate perpendicular to its axis of articulation; incisor on outer side with longitudinal plate; this plate bears a regular row of large transverse pectinate projection, forming a scraper or filter of unique structure (Penniket 1966: Fig.11-15).

(2) Maxilla [with 3 dentisetae – see Anteritorna (2)] is strongly widened and has unique structure; its initial median margin projects in such a manner that 2^nd and 3^rd (proximal) dentisetae are located on this projection, and 1^st (distal) dentiseta is located on a straight margin directed apically; all 3 canines are flat, with unusually wide bases [Penniket (1966) erroneously wrote that canines are "movable" and "arising from the same point"]; initial apical margin is directed laterally, initial apical setae are lost (Kluge 2004: Fig.36:A).

(3) On hind wing bifurcation of MP [third triad – see Euplectoptera (1)] is nearer to wing margin than to wing base, more distal than bifurcations of RS and MA (Penniket 1966: Fig.1). Non-unique apomorphy (see Index of characters [2.2.69]). In other respects hind wing is well developed, as long as about 0.475 of fore wing length.

Characters of Rallidens of unclear phylogenetic status.

(4) Maxilla [see (1)] with a small finger-like gill located laterally at articulation of cardo and stipes (Kluge 2004: Fig.36:A). The same in Nesameletus/f1=Metamonius/g1; possibly, synapomorphy.

(5) Tergalii have peculiar structure. Each tergalius I–VII has fibrillose lobe arising from ventral side near base (Kluge 2004: Fig.36:B) (the same in Branchitergaliae and selected Ameletopsis/fg1 – see Index of characters [1.3.25]). On each tergalius III–VII anal rib bifurcates near base, thus there are 3 ribs: costal rib is situated on costal margin and in its distal part bears denticles; anterior branch of anal rib is situated on dorsal surface near middle of tergalius just behind main trachea (like anal rib of Siphlonurus/fg1, Dipteromimus and some Ameletus/fg1); posterior branch of anal rib borders proximal part of anal margin behind base of the fibrillose lobe (such 3 ribs are present also in Nesameletus/f2=Metamonius/g2 and Isonychia/fg1). Tergalii I–II have no denticles, ribs of tergalius II are vestigial, tergalius I lacks ribs.

(6) Imaginal and subimaginal anterior paracoxal suture of mesothorax is incomplete – i.e. not continued on ventral side of episternum and terminates not reaching sternum (Kluge 2004: Fig.36:C-D). In all other Tridentiseta anterior paracoxal suture is complete. Probably, this is an autapomorphy of Rallidens; besides Rallidens, the anterior paracoxal suture is incomplete in Heptagennota and Furcatergaliae.

(7) Imaginal and subimaginal furcasternal protuberances are not contiguous, furcasternal median impression is parallel-sided, not widened posteriorly; metathoracic nerve ganglion is situated in posterior part of furcasternum (Kluge 2004: Fig.36:C). Non-unique apomorphy (see Index of characters [2.2.23]); among Tridentiseta the same in other Amphinotic groups – Nesameletus/f2=Metamonius/g2, Vetulata and Ameletopsis/fg1.

(8) Larval paraproct with a spine on inner-apical margin. The same in Siphlonurus/fg2, Metertopus/fg1, Siphluriscus and Vetulata.

(9) Imaginal and subimaginal paracercus is strongly diminished. Non-unique apomorphy (see Index of characters [2.3.22]).

Plesiomorphies of Rallidens. Larva has primary swimming siphlonuroid specialization: legs are able to stretch posteriorly; abdomen is large, able to make undulate swimming movements; caudalii are not long, paracercus is well-developed, primary swimming setae are dense, secondary swimming setae are absent. Larval head is hypognathous. Maxillary palp is 3-segmented. Labial palp is 3-segmented. Larval (and adult) patella-tibial suture is developed on middle and hind legs only. Larval claws are slightly curved, without denticles.

In imago and subimago: Mesonotal suture is nearly transverse (Kluge 2004: Fig.36:D). In cubital field of fore wing several (5–6) veins go from CuA to basitornal margin [see Anteritorna (1)]. Imaginal and subimaginal tarsi are 5-segmented, 1^st segment is non-shortened and fused with tibia. All claws of imago and subimago are ephemeropteroid. Gonostylus with 2 distal segments.