CLADOENDESIS OF EPHEMEROPTERA

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Systematic position of Anafroptilum is vague: from one hand, it shares some peculiar characters common with Cloeon/fg1; from other hand, its patella-tibial suture is characteristic for the taxon Protopatellata, while Cloeon/fg1 do not belong to Protopatellata.

Character of Anafroptilum common with Protopatellata. 

(1) In larva, subimago and imago of both sexes patella-tibial suture is absent on fore legs and present on middle and hind legs (Kluge 2012: Fig.38-39). This character is plesiomorphic, being the same as in the outgroup, i.e. in the most non-baetid mayflies and in the primitive baetid taxa, Siphlaenigma and Palaeocloeon. Among Turbanoculata, this character is present in the taxon Protopatellata. In contrast to this, the taxon Anteropatellata (comprising overwhelming majority of Baetidae) is characterized by presence of patella-tibial suture on all legs other than fore legs of male imago and subimago. Exceptions are made only by representatives with highly modified leg structure; unlike them, Anafroptilum has leg structure non-modified, similar to that of Cloeon/fg1 and many other taxa.

Characters of Anafroptilum common with Cloeon/fg1. In contrast to Anafroptilum, all representatives of Cloeon/fg1 have patella-tibial suture equally developed on all legs of larva and female, so Cloeon/fg1 undoubtedly belong to Anteropatellata. Besides evident symplesiomorphies, Anafroptilum and Cloeon/fg1 share the following common characters: 

(2) Larval labial palp with 3rd segment truncate and 2nd segment non-projected (Kluge 2012: Fig.46; Kluge & Novikova 2017: Fig.16, 78). The same in some other taxa.

(3) Larval abdominal segments VIII and IX with spines forming one longitudinal row on each lateral margin (Kluge 2012: Fig.41); sometimes such spines are present also on some of previous abdominal segments. This character is constant for Cloeon/fg1 and not found in any taxa other than Cloeon/fg1 and Anafroptilum. Among Anafroptilum, these spines are either constantly present (e.g. kazlauskasi [Centroptilum], bifurcatum [Centroptilum],  victoriae [Centroptilum]), or occasionally absent (in album [Centroptilum], conturbatum [Centroptilum]), or constantly absent (in odontostylus [Anafroptilum], orthostylus [Anafroptilum]). 

(4) Male imaginal gonovectes are fused with penial bridge (Kluge 2012: Fig.45; Kluge & Novikova 2017: Fig.41, 79). Among Protopatellata, the same in Rhithrocloeon/fg1 and Demoulinia – see Index of characters [2.3.16a].

Symplesiomorphies of Anafroptilum, Cloeon/fg1, some Protopatellata and some other taxa. 

(5) Larval claw with 2 equal rows of denticles (in contrast to Baetungulata and some other taxa). 

(6) Fore wings with no more than one marginal intercalary in each space (unlike Baetovectata) [see Liberevenata (2)] (Index of characters [2.2.55]).

(7) In subimago of both sexes either all segments of all tarsi are covered with pointed microlepides, or only proximal part of tarsus is covered with microtrichiae (Kluge & Novikova 2017: Fig.49); blunt microlepides are absent on all tarsomeres (in contrast to Baetungulata). 

(8) Subimaginal gonostyli developing under larval cuticle are folded in «Cloeon-type» pose (Kluge 2012: Fig.54; Kluge & Novikova 2017: Fig.43) (in contrast to Baetovectata).

Characters of Anafroptilum of unclear phylogenetic status. 

(9) Dorsal surface of labrum with irregularly situated setae, without constant pair of submedian setae and without regular latero-distal setal rows (Kluge & Novikova 2017: Fig.35, 76). The same in Centroptilum, some Cloeon/fg1 and some other (see Index of characters [1.1.14]).  

(10) Mandibles of «Centroptilum-type»: kinetodontium is separated from incisor (but immovable) and rotated perpendicular to the plane of mandible, so that its denticles hide one another in dorsal or ventral view; left prostheca is bifurcate and rotated in the same manner  (Kluge & Novikova 2017: Fig.13–14, 38–39, 61–62) (see Index of characters [1.1.22], [1.1.24]). 

(11) Both mandibles with dense setae between prostheca and mola (Kluge & Novikova 2017: Fig.13–14, 61–62). The same in all Cloeon/fg1, Centroptilum and some others. 

(12) Maxilla of the «Cloeon-type», i.e. with all 3 canines and 3 dentisetae slender, pointed and bent at the same direction (Kluge & Novikova 2017: Fig.17, 77). The same in many other taxa.

(13) Glossa and paraglossa of the «Cloeon-type», i.e. subequal in length and width, pointed, paraglossa with no more than one regular row on outer-apical margin (Kluge 2012: Fig.46; Kluge & Novikova 2017: Fig.36, 78). The same in many other taxa. 

(14) Larval femora without row of stout setae on outer margin and without stout outer-apical setae; outer-apical margin serrate, with sparse thin hairs (Kluge & Novikova 2017: Fig.59). The same in Centroptilum and selected species of Procloeon/g1.

() ???Larval tibiae of all legs without outer-apical seta (see Index of characters [1.2.17]).

() Male imaginal gonostylus with 2nd segment thickened apically, 3rd segment petiolate (Kluge 2012: Fig.45; Kluge & Novikova 2017: Fig.41, 79). In Cloeon/fg1 second segment of gonostylus is also widened apically, and third segment is also petiolate, but smaller. In other respects external genitals of Anafroptilum are highly variable: 1st segment of gonostylus either with characteristic projection on inner side, or without it; 2nd segment either arched, or straight; median finger-like projection either present, or absent.

Variable characters of Anafroptilum. 

() Hind wings either present, or absent (in minor [Cloeon], odontostylus [Anafroptilum], orthostylus [Anafroptilum]). If present, hind wing is either of the «Baetis-type», i.e. relatively wide, with three longitudinal veins and short costal projection (e.g., in bifurcatum [Centroptilum]), or of the «Centroptilum-type», i.e. narrow, with two longitudinal veins and hooked costal projection (e.g., in kazlauskasi [Centroptilum]). 

() Tergalii either asymmetrically widened (Kluge & Novikova 2017: Fig. 69–75), or narrow and symmetric (Kluge & Novikova 2017: Fig.28–34).