CLADOENDESIS OF EPHEMEROPTERA

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Autapomorphies of Atalophlebomaxillata.

(1) Distal dentiseta is usually lost, so apical angle of maxilla bear a single proximal dentiseta, which is pectinate and directed distally like a comb [see Atalophlebopectinata (1)] (Kluge 2012: Figs 2,4,5). In a few taxa this dentiseta is also lost (see Index of characters [1.1.37, 39]).

Among Atalophlebomaxillata, Aprionyx has the distal dentiseta retained; its distal dentiseta is somewhat smaller than in Terpides/fg1 and can be poorly visible, being pressed to the dense apical filtering setae. At the same time, hypopharynx of Aprionyx has a pair of processes typical for Atalophlebolinguata. Some individuals of Atalophlebomaxillata have the single dentiseta bifurcate, with a slender non-pectinate distal branch; possibly, this branch is a vestige of the distal dentiseta basally fused with the proximal dentiseta; if this is so, presence of such branch is a transitional condition between presence of the distal dentiseta and its absence.

(2) Maxilla has an apical flange, which represent a continuation of its ventral wall to apical direction and separates the apical field of long filtering setae [see Leptophlebia/fg1 (1)] from the apical-ventral row of pectinate setae [see Leptophlebia/fg1 (1)]; thanks to the apical flange, the apical field of long filtering setae is shifted to the dorsal side of maxilla and its ventral margin locates far from the apical-ventral row of pectinate setae (Kluge 2012: Fig.3). The apical flange reaches inner margin of maxilla, and laterally terminates fare from outer margin of maxilla (Kluge 2012: Fig.2). The apical flange is very thin and translucent, so it is poorly visible on background of dense apical filtering setae. In my previous paper maxilla of Farrodes bimaculatus Peters & Alayo 1971 was shown wrongly, without the apical flange (Kluge 1994: Fig.4); actually it has the apical flange similar to that in Fig. 2.

Among the taxa examined, the apical flange is reduced only in taxa with highly specialized maxillae of the «Dilatognathus-like type» — Hermanellognatha (Kluge 2008: Fig.37), Notophlebia, Hagenulus morrisonae (but not Hagenulus caligatus) and last instar larva of Dilatognathus (Kluge 2012: Fig.129) (but not its younger larvae — ibid., Fig. 132).

Unlike Atalophlebomaxillata, in other Leptophlebia/fg1 (i.e., Terpides/fg1, Habrophlebia/fg1, Calliarcys/fg(1) and the plesiomorphon Leptophlebia/fg2) the apical flange is absent, the apical field of long filtering setae is located at most on ventral side of maxilla, and its ventral margin is located close to the apical-ventral row of pectinate setae (Kluge 2012: Fig.1, Kluge, 2009: Fig.1).

() Hear prognathoius and flattened dorsoventrally; clypeus and labrum directed anteriorly (rather than ventrally in other Leptopohlebia/fg1); mandibles are flattened and widened, with convex outer margin; their incisors and kinetodontia are slender, with constant number of terminal denticles (3 on both incisors and left kinetodontium, 2 on right kinetodontium), with or without side denticles. Exception is made by Tenagophila, whose head is hypognathous, with stout pyramidal mandibles similar to that of Leptophlebia/fg1-non-Atalophlebomaxillata.