CLADOENDESIS OF EPHEMEROPTERA

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Autapomorphies of Guajirolus/g1 (characters common with Pseudopannota/g2 marked by brown).

(1) Modification of labrum. Labrum has peculiar structure (Kluge 2019: Fig.4-11; Nieto 2003: Fig.3A; Falcão & Salles & Hamada 2011: Fig.81). In contrast to most other Baetidae, whose labrum has rigid distal margin armed with a sclerotized edge, labrum of Guajirilus/g1 has distal margin soft, covered by non-sclerotized membranous cuticle; it retains a median emargination, but more lateral areas represent a pair of soft sacks of changeable shape and size, densely and irregularly covered by fine setae (Fig. 6). Outer (i.e. dorsal) surface of labrum has only irregular setation, and no any constant setae (Fig. 10); particularly, there are no paired submedian and latero-distal setae, which are present in many other Baetidae. Inner (i.e. ventral) side of labrum bears a pair of regular rows of spine-like, stout, pointed, arched setae; each row runs along lateral and apical margins of labrum and terminates near the median emargination (Fig. 9, 19); in other Baetidae such ventral submarginal setal rows, if present, consist of more soft setae.

(2) Reduction of mandibular incisors. On both mandibles biting denticles are formed mainly by kinetodontium, while incisor is greatly reduced (Kluge 2019: Fig.12-13; 20-21; Nieto 2003: Fig.3B-C).

(3) Protuberance on mandibles. On both mandibles, inner margin between prostheca and mola is heavily sclerotized and projected just proximad of prostheca, forming right angle, so that base of prostheca is inserted into incision between base of kinetodontium and this right-angled projection; on both mandibles margin between this angle and mola is densely setose (Kluge 2019: Fig.12-13; 20-21; Nieto 2003: Fig.3B-C).

(4) Hypopharynx with lateral portions projected distally; apical margin between them either represent a deep concavity between these projections, or forms a third, median projection arising from this concavity (Kluge 2019: Fig.25-28; Falcão & Salles & Hamada 2011: Fig.82).

(5) Shape of maxilla. Maxilla with biting margin long, with all three canines and all three dentisetae long and slender; apex of maxilla with tuft of long setae, located laterad of canines (Kluge 2019: Fig.17-18; Nieto 2003: Fig.3E-F).

(6) Pseudo-three-segmented maxillary palp. Maxillary palp [2-segmented – see Baetungulata (3)] has 1st segment divided into 2 parts (subsegments). In Chane this division represents an incomplete seem at proximal part of the 1st palpomere, so that the palp retains 2-segmented appearance (Nieto 2003: Fig.3E–F; Falcão & Salles & Hamada 2011: Fig.80); in Guajirolus/g2 two subsegments of the 1st palpomere are long and movably articulated, so that the palp looks as 3-segmented (Kluge 2019: Fig.17, 22–24). Muscle, located in the 1st palpomere and moving the 2nd palpomere, runs through both subsegments of the 1st palpomere; this fact proves that these are subsegments of one segment, but not true segments.

(7) Labial palp (3-segmented, that is initial for mayflies and insects in general) has 2nd segment greatly projected medially, so that the palp has chelate form. Muscle located in the 2nd palpomere and moving the 3rd palpomere, is retained, so that 3rd palpomere can be pressed to the projection of 2nd palpomere (Kluge 2019: Fig.29,31; Falcão & Salles & Hamada 2011: Fig.78). In Guajirolus/g2 projection of 2nd palpomere is unusually thick (Kluge 2019: Fig.29-35); in Chane this projection and 3rd palpomere are greatly elongate and both bear rows of long filtering setae (Nieto 2003: Fig.3G). Besides Guajirolus/g1, more or less prominent medio-apical projection of 2nd palpomere is found in various other taxa, but not as large as in Guajirolus/g1.

(8) Larval femur on outer side with pointed stout setae of variable size, not forming regular row and without determined two apical setae. Fore femur thicker than others (Kluge 2019: Fig.44-45; Nieto 2003: Fig.3H).

(9) Larval claw has unusual structure (Kluge 2019: Fig.46-47; Falcão & Salles & Hamada 2011: Fig.79, 107). As in other Baetungulata, it bears on inner side asymmetrically located inner-anterior row of denticles, while the inner-posterior row is completely lost [see Baetungulata (1)]. The most distal denticle is much larger (longer and thicker) than others and located not in one line with others, but symmetrically (i.e. not shifted toward anterior or posterior side of the claw); the neighboring denticle (i.e. the most distal denticle among denticles shifted toward anterior side) is arched distally, longer and thinner than following denticles. Distal part of claw (distad of denticles) without symmetric oblique striation [in contrast to many other Baetidae (Kluge & Novikova 2016: Fig.21,23)]. Among Baetidae, besides Guajirolus/g1, enlarged symmetric denticles are present in a non-related species quadridentatus [Paracloeodes]. Enlarged distal denticle followed by thinned denticle, besides Guajirolus/g1, is found in leptophlebiid genus Adenophlebiodes.

(10) Male imago of ektrapeloglossa [Guajirolus] and male imago ascribed to baure [Chane] have great similarity: nearly unicolor brown with legs and cerci unicolor pale yellow; turbinate eyes are low, with facetted surfaces very sharply widened, brown with dark brown ring bordering facetted surface (Kluge 2019: Fig.70-71; Nieto 2003: Fig.2A); gonostyli have the same shape (Kluge 2019: Fig.77-80; Nieto 2003: Fig.2C). As imagines of baure [Chane] are not reared from larvae, assumption about there belonging to this species is preliminary.

Plesiomorphies and characters of  Guajirolus/g1 of unclear phylogenetic status, different from Labiobaetis/f1=Pseudopannota/g1.

(11) Sterno-styligeral muscle is retained (Kluge 2019: Fig.75). This character is known only for ektrapeloglossa [ Guajirolus].

(12) In mature larva ready to molt to subimago, subimaginal gonostyli are folded by the «Guajirolus-type»: 2nd segment is crumpled laterally; 3rd segment is attached on caudal side of 2nd segment and bent medially (Klige 2019: Fig.76). Such mode of gonostyli folding is similar to the «Nigrobaetis-type», but in contrast to it, the 3rd segment is directed not caudally, but medially. This character is known only for ektrapeloglossa [ Guajirolus]. In contrast to Pseudopannota/g2 and other Labiobaetis/f1=Pseudopannota/g1, whose gonostyli are folded by the «Labiobaetis-type» [comp.: Labiobaetis/f1=Pseudopannota/g2 (2)].

(13) Imaginal gonostylus has 2nd segment is markedly widened at the apex, and 3rd segment is clavate and petiolate (Kluge 2019: Fig.77-80; Nieto 2003: Fig.2C).

(14) Larval abdomen with scales in operculate sockets (Kluge 2019: Fig.60–61), that is probably initial [see Turbanoculata (12)]. In contrast to Pseudopannota/g2 and other Labiobaetis/f1=Pseudopannota/g2, whose scales, if present, have simple semicircular sockets without operculae.