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Bojophlebia prokopi Kukalov a-Peck, 1985, holotype, overview (scale bar D 4 cm). The elevations appear to be reversed due to lighting from below, so that the legs only seem to be lower than the wing and ScP only seems to be concave (as in Figs 5, 6, 7 and 9A).
Source publication
The holotype is redescribed of the giant pterygote insect Bojophlebia prokopi Kukalová-Peck, 1985 from the Pennsylvanian of the Czech Republic. Multiple errors in the original description are documented and corrected. Bojophlebia prokopi has neither any visible traces of a costal brace nor an anal brace, but it does show triadic branchings of MA, M...
Contexts in source publication
Context 1
... structures of the rock matrix that are also visible outside of the wing area. Abdomen. “ abdomen with two segments ” (Kukalov a- Peck 1985, species description, p. 936, but see also fig. 2, p. 935); “ cerci and paracercus probably with short hair, cerci shorter than paracercus ” (Kukalov a-Peck 1985, generic description, p. 936). There are not just two abdominal segments present as described by Kukalov a-Peck, but actually the first four segments are complete and the fifth segment is partially preserved. Shape and dimensions of the preserved abdominal segments also differ strongly from the drawing of Kukalov a-Peck (1985), which appears to be very schematic in this respect. The statement in the generic description regarding the terminal filaments again is a mere assumption by Kukalov a-Peck that is not supported by any evidence (see Fig. 1). It is obvious from the preceding paragraphs that Kukalov a- Peck’s original description suffers from erroneous observations and over-interpretations. This finding is reinforced by the fact that other authors in their revisions of fossils described by Kukalov a-Peck found similar shortcomings (Carpenter 1987; Rasnitsyn & Novokshonov 1997; Willmann 1999; B ethoux & Briggs 2008; Staniczek et al. 2014). Several phylogenetically relevant character states that were documented in the original description turned out either not to be present in the actual fossil specimen at all, or to have a different state than that described. Hence, the conclusions suggested by Kukalov a-Peck for the phylogenetic affinities of Bojophlebia prokopi and the evolution of early mayflies are unsubstantiated. Contrary to a common misconception, traditional Hennigian phylogenetic systematics does not involve a ‘manual’ but rather a ‘mental’ analysis of character patterns (Bechly 2000). This includes a careful description and comparison of the characters, as well as a weighting of their phylogenetic relevance based on reasonable estima- tions of their probability for homoplasy. Complex and rare derived character states are weighted higher than simple and often independently evolved character states. Like computer cladistics, Hennigian phylogenetic systematics relies on the principle of parsimony (‘Occam’s razor’). However, it does not agree with computer cladistics that the principle of parsimony is exhausted by the procedure of minimizing the number of character transfor- mations, but also considers the plausibility of the implied homology hypotheses and evolutionary transitions. This rejection of always preferring the shortest trees is right in the spirit of Einstein’s famous quote ‘Everything should be made as simple as possible, but not simpler’. Character polarities are established by an a priori outgroup comparison (to be distinguished from a posteriori outgroup rooting in computer cladistics), for which representatives are preferably selected from several basal lineages of taxa that are certainly outside the group in study but nevertheless closely related. This does not involve the logical fallacy of circular reasoning, but an abductive inference of the best explanation that was called ‘mutual enlightenment’ by Willi Hennig and that resembles the methodology of the hermeneutic spiral. Ground plans are reconstructed by inferring all relevant plesiomorphic and apomorphic character states for the most recent common ancestor of a clade using the same procedure of outgroup comparison. Our study of Bojophlebia allows a revised diagnosis for the family Bojophlebiidae: very large size with a wing span of nearly 40 cm (autapomorphy); forewing with large basal costal field (plesiomorphy); costal brace absent in both wings (plesiomorphy); ScP very thick (autapomorphy); ScP and RA very long, nearly reaching apex (plesiomorphy); RA and RP closely parallel, but remaining separated basally (plesiomorphy); MA attached to RP without anterior connection of MA to MP (autapomorphy, con- vergent with Ephemerida and higher Odonatoptera); CuP branched (plesiomorphy, except for a possible reversal in Miracopteridae); MA, MP, CuA, CuP with intercalaries developed as triadic branchings (synapomorphy with Hydropalaeoptera, otherwise only present as a convergence in the hind wing of the highly aberrant palaeodictyopteran Lodetiella magnifica B ethoux et al ., 2007), thus as dichoto- mous branching of a main longitudinal vein that is bracket- ing a long and straight intercalary vein of opposite corrugation; hind wing base broader than in forewing, with large anal field (anal fan) composed of alternating concave and convex veins (plesiomorphy); glossae developed as enlarged plates (autapomorphy). The polarity of these characters is based on an outgroup comparison with the ground patterns as exhibited by the most basal lineages of Ephemerida, Odonatoptera, Palaeodictyopterida and Neoptera. A remarkable feature of Bojophlebia is the presence of a very thick ScP compared to RA. In most pterygote taxa, RA is the thickest vein in the wing. This unique autapomorphy could suggest a different scheme of wing articulation in Bojophlebia , which is unfortunately not preserved in the single known fossil. Even though the most distal parts of the wings are not preserved, the veins ScP and RA most probably reached close to the wing apex. This character was mentioned by Kluge & Sinitshenkova (2002) as one of the diagnostic characters of Ephemerida, but it seems instead to be a symplesiomorphy because it is also present in some basal Palaeodictyoptera (e.g. Megaptilidae, Eugereonidae and ...
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... The holotype and single known specimen is rather poorly preserved, as already indicated by previous authors who had briefly re-examined the fossil (Prokop et al. 2010; Staniczek et al. 2011). The fossil is visible from its ventral side, because legs are superimposed on the wing veins, thoracic sternites are clearly visible, and the corrugation of the wing veins is reversed (concave veins are convex and vice versa). Head, thorax, proximal part of abdomen, fragments of legs, and basal parts of all four wings are preserved ( Fig. 1). For measurements see Table 1. Head. Prognathous. Antennae not preserved. Mouth parts visible from ventral side (Fig. 2). The ventral closure of the mouth parts in insects is formed by the labium, so the most likely interpretation is given in Figure 2. The labium is enlarged and obscures most of the remaining mouth parts that are situated more dorsally. The two medioapi- cal, paired, oval structures are interpreted here as large glossae (gl); laterodorsally to these the smaller paraglossae (pgl) are visible. The left paraglossa is only partly preserved. Posterior to glossae and paraglossae, a short prementum (prm) and postmentum (pm) follow. On its right side, the labium is somewhat distorted; in particular the postmentum is medially cracked and, together with the prementum, displaced and shifted anterolaterad. On the right side, a three-segmented labial palp (plb) inserts laterally at the prementum. The apical part of the corresponding left labial palp is not preserved, only the first segment is visible, but bent posteriorly. Basal part of right maxilla preserved (ca, st). Other mouth parts not visible. Thorax. Division into pro-, meso- and metathorax clearly visible (Fig. 3). Prothorax smallest of all thoracic segments, meso- and metathorax of approximately same length. Prothoracic wings or paranota not present. The thoracic sterna show multiple sclerites, for which we here suggest a tentative homologization, based on a comparison with Recent mayflies (Tsui & Peters 1975). Prothorax. With two sclerites that we interpret as basi- and furcasternum (bs1, fs1). Mesothorax. With several discernible sclerites. Antero- laterally, the episternum extends to the basisternum (bs2). The episternum is divided into an anterior anepisternum (AES) and a posterior katepisternum (KES). The episterna are medially separated by the basisternum (bs2). Posteriorly to the basisternum, a large furcasternum (fs2) is present. The lateral parts of the furcasternum are bulged, forming a pair of furcasternal protuberances (fsp). Laterally of the furcasternum, an epimeron (EM) is visible. Metathorax. With large, rectangular basisternum (bs3) and furcasternal protuberances as in mesosternum. In none of the three sterna could a separate spinasternum be identified. Legs. Long and slender; probably mainly used for cling- ing to the vegetation (Fig. 1). For measurements see Table 1. In all visible legs, femora, tibiae, and tarsomeres are at least partially preserved. Neither a separate patellar segment nor tarsal claws are visible in any of the preserved legs (Fig. 4). A small number of scattered spines in a row are discernable on the surface of femora and tibiae. Right foreleg almost completely preserved except for tarsus ...
Context 3
... The holotype and single known specimen is rather poorly preserved, as already indicated by previous authors who had briefly re-examined the fossil (Prokop et al. 2010; Staniczek et al. 2011). The fossil is visible from its ventral side, because legs are superimposed on the wing veins, thoracic sternites are clearly visible, and the corrugation of the wing veins is reversed (concave veins are convex and vice versa). Head, thorax, proximal part of abdomen, fragments of legs, and basal parts of all four wings are preserved ( Fig. 1). For measurements see Table 1. Head. Prognathous. Antennae not preserved. Mouth parts visible from ventral side (Fig. 2). The ventral closure of the mouth parts in insects is formed by the labium, so the most likely interpretation is given in Figure 2. The labium is enlarged and obscures most of the remaining mouth parts that are situated more dorsally. The two medioapi- cal, paired, oval structures are interpreted here as large glossae (gl); laterodorsally to these the smaller paraglossae (pgl) are visible. The left paraglossa is only partly preserved. Posterior to glossae and paraglossae, a short prementum (prm) and postmentum (pm) follow. On its right side, the labium is somewhat distorted; in particular the postmentum is medially cracked and, together with the prementum, displaced and shifted anterolaterad. On the right side, a three-segmented labial palp (plb) inserts laterally at the prementum. The apical part of the corresponding left labial palp is not preserved, only the first segment is visible, but bent posteriorly. Basal part of right maxilla preserved (ca, st). Other mouth parts not visible. Thorax. Division into pro-, meso- and metathorax clearly visible (Fig. 3). Prothorax smallest of all thoracic segments, meso- and metathorax of approximately same length. Prothoracic wings or paranota not present. The thoracic sterna show multiple sclerites, for which we here suggest a tentative homologization, based on a comparison with Recent mayflies (Tsui & Peters 1975). Prothorax. With two sclerites that we interpret as basi- and furcasternum (bs1, fs1). Mesothorax. With several discernible sclerites. Antero- laterally, the episternum extends to the basisternum (bs2). The episternum is divided into an anterior anepisternum (AES) and a posterior katepisternum (KES). The episterna are medially separated by the basisternum (bs2). Posteriorly to the basisternum, a large furcasternum (fs2) is present. The lateral parts of the furcasternum are bulged, forming a pair of furcasternal protuberances (fsp). Laterally of the furcasternum, an epimeron (EM) is visible. Metathorax. With large, rectangular basisternum (bs3) and furcasternal protuberances as in mesosternum. In none of the three sterna could a separate spinasternum be identified. Legs. Long and slender; probably mainly used for cling- ing to the vegetation (Fig. 1). For measurements see Table 1. In all visible legs, femora, tibiae, and tarsomeres are at least partially preserved. Neither a separate patellar segment nor tarsal claws are visible in any of the preserved legs (Fig. 4). A small number of scattered spines in a row are discernable on the surface of femora and tibiae. Right foreleg almost completely preserved except for tarsus ...
Similar publications
Phylogenetic relationships among the basal orders of winged insects remain unclear, in particular the relationship of the Ephemeroptera (mayflies) and the Odonata (dragonflies and damselflies) with the Neoptera. Insect evolution is thought to have followed rapid divergence in the distant past and phylogenetic reconstruction may therefore be suscept...
Citations
... It is uncertain whether this fossil is a fore or a hind wing, even though the shape of the posterior wing margin suggests a forewing. We attribute it to the Palaeodictyoptera rather than to the clade [Megasecoptera + Permothemistida + Diaphanopterodea] because of the broad costal area (Sroka et al., 2015), numerous faint irregular crossveins, a faint color pattern of oblique stripes, a RP very long as in Palaeodictyoptera, and a ra-rp area much broader than the scp-ra area, as in Palaeodictyoptera. Logghe et al. (2022) have already indicated that "the current classification of the Palaeodictyoptera is not satisfactory". ...
A new species of palaeodictyopteridan insect, Heolus martinclosasi sp. nov., based on a partial wing, has been identified in the uppermost Pennsylvanian (Stephanian C local stage) deposits of the Castellar de N’Hug-Camprodon Basin, located in the Surroca-Ogassa coalfield within the Pyrenees of Catalonia, Spain. This species belongs to the Palaeodictyoptera, and is the first of this order described from the Paleozoic deposits of Spain. Heolus martinclosasi sp. nov. is the second species within the relatively small Heolidae family, originally described by Handlirsch in 1906, in the USA. This new species was found alongside remains of in situ fossil plants such as Calamites suckowii, Sphenophyllum oblongifolium, and marattialean tree ferns, all of which grew between river channels. This suggests that these insects possibly lived in lake-like, permanently inundated floodplain deposits.
... This conclusion, however, was based on a cladogram only using a dataset of recent species and omitted the enormous record of extinct relatives traceable back at least for 300 mya [10][11][12] . The origin of the Pterygota and habitat or lifestyles of the ancestor of pterygotes are key questions, which could be better understood when fossils from the Late Paleozoic, particularly those with marked apomorphies/specializations at the super ordinal level such as Palaeodictyopterida, are considered 13,14 . According to Sharma 9 , ancestral state reconstructions must be interpreted critically, particularly when based only on extant groups (terminals) and when the fossil record for a group suggests historical extinctions of higher-level clades. ...
... The superorder Palaeodictyopterida with specialized piercing and sucking mouthparts in the form of a rostrum is among the first recorded pterygotes and its phylogenetic placement as stem group of Neoptera is resolved 13,14,20 . Specializations for aquatic or semiaquatic lifestyles in larvae of Palaeodictyoptera have been studied for more than a century, but the interpretations differ greatly [21][22][23][24][25] . ...
One of the fundamental questions in insect evolution is the origin of their wings and primary function of ancestral wing precursors. Recent phylogenomic and comparative morphological studies broadly support a terrestrial ancestor of pterygotes, but an aquatic or semiaquatic ancestor cannot be ruled out. Here new features of the branchial system of palaeodictyopteran larvae of several different instars of Katosaxoniapteron brauneri gen. et sp. nov. (Eugereonoidea) from the late Carboniferous collected at Piesberg (Germany) are described, which consist of delicate dorsolateral and lamellate caudal abdominal gills that support an aquatic or at least semiaquatic lifestyle for these insects. Moreover, the similar form and surface microstructures on the lateral abdominal outgrowths and thoracic wing pads indicate that paired serial outgrowths on segments of both tagmata presumably functioned as ancestral type of gills resembling a protopterygote model. This is consistent with the hypothesis that the wing sheaths of later stage damselfly larvae in hypoxic conditions have a respiratory role similar to abdominal tracheal gills. Hence, the primary function and driving force for the evolution of the precursors of wing pads and their abdominal homologues could be respiration.
... This noteworthy finding suggests that bullae were present throughout Ephemerida and therefore hardens the evidence for the presence of a subimaginal stage at least in stemgroup mayflies. Bullae should be reliable indicators for the presence of adult moultings also in other fossil Palaeopterous groups like Odonatoptera or Palaeodictyopterida (for an overview see [44]), provided that such delicate structures are preserved in pristine condition. Most interesting however is that the bullae were found in a hind wing. ...
Background
Mayflies are basal winged insects of crucial importance for the understanding of the early evolution of Pterygota. Unlike all other insects, they have two successive winged stages, the subimago and the imago. Their forewings feature so-called bullae, which are desclerotized spots in the anterior main veins. Up to now, they have been considered to play a major role in wing bending during flight.
Results
We investigated bullae by multiple methods to reveal their structure and arrangement and to gain new information on the evolution of insect flight. Bullae are mostly present in the anterior negative wing veins, disrupting the otherwise rigid veins. High-speed videography reveals that mayfly wings do not bend during flight. Likewise, different arrangements of bullae in different species do not correlate with different modes of flying. Observations on the moulting of subimagines unravel that they are essential for wing bending during the extraction of the imaginal wing from the subimaginal cuticle. Bullae define predetermined bending lines, which, together with a highly flexible wing membrane enriched with resilin, permit wing bending during subimaginal moulting. Bullae are only absent in those species that remain in the subimaginal stage or that use modified modes of moulting. Bullae are also visible in fossil mayflies and can be traced back to stemgroup mayflies of the Early Permian, the 270 million years old Protereismatidae, which most probably had bullae in both fore- and hind wings.
Conclusions
Bullae in mayfly wings do not play a role in flight as previously thought, but are crucial for wing bending during subimaginal moulting. Thus, the presence of bullae is a reliable morphological marker for a subimaginal life stage, confirming the existence of the subimago already in Permian Protereismatidae. A thorough search for bullae in fossils of other pterygote lineages may reveal wheather they also had subimagines and at what point in evolution this life stage was lost. In mayflies, however, the subimago may have been retained due to selective advantages in connection with the transition from aquatic to terrestrial life or due to morphological requirements for a specialized mating flight.
... We provisionally consider that Corydaloides leon ensis belongs to the Megasecoptera, with a restriction about the monophyly of this order. Yang et al. (2020) considered it as paraphyletic on the basis of a rather weak argument (see remark below), and Sroka et al. (2015) did not propose any synapomorphy for the Megasecoptera. Because of the lack of any phylogenetic analysis of the Megasecoptera, we need to compare Corydaloides leonensis with all the megasecopteran families. ...
... : 1016 already noticed that 'the wings resting position [in Diaphanopterodea] is not really suitable for ordinal diagnosis: isolated wings cannot be assigned, and taphonomic bias can render interpretations of wing disposal difficult' . As Sroka et al. (2015) proposed, the two orders Megasecoptera and Diaphanopterodea were part of the same clade together with Permothemistida, supported by the character 'Forewing costal field not very large and broad; archaedictyon reduced, the stablishedment of a clade Megasecopteromorpha could be reasonable but, as the position of the Permothemis-tida is ambiguous after Yang et al. (2020), a further phylogenetic analysis will be necessary to clarify the relationships between all the palaeodictyopteridan orders. ...
Here we present a state of the art of the Upper Carboniferous insects from the Iberian Peninsula, including new fossils of Panorthoptera (Archaeorthoptera), and of the orders Paoliida, Megasecoptera, and Palaeodictyoptera. These fossils are from Gzhelian deposits of different coalfields in León Province (Castilla y León, NW Spain). Among the insect orders, we have described the archaeorthopteran Hispanopteron romerali gen. et sp. nov., the Paoliida Simplexpaolia prokopi gen. et sp. nov., the megasecopterans Mischoptera bergidensis sp. nov. and Corydaloides leonensis sp. nov., in addition to an unnamed prothoracic winglet of palaeodictyopteran. The taxon Hispanopteron romerali is the sixth archaeorthopteran described or cited from the Iberian Peninsula, and increases the impressive diversity of the superorder. Simplexpaolia prokopi represents a new genus and species of latest Carboniferous Paoliidae and the first representative of this family in Spain. Corydaloides leonensis sp. nov. and Mischoptera bergidensis sp. nov. represent the second and third records of the order Megasecoptera in Spain, respectively, as well as the first specimens of the Corydaloididae and Mischopteridae families in the Iberian Peninsula. The deposition of these insect remains together with different fossils of plants, and the previously published evidence of diverse plant-insect interactions, suggest that the Gzhelian entomofauna found in the vegetation of these Carboniferous forests had already occupied numerous ecological niches under a tropical climate. In addition, we have carried out the review of all insect remains, and evidence of plant-insect interactions found so far from the Carboniferous of the Iberian Peninsula, observing a higher diversity than expected. © 2022 E. Schweizerbart’sche Verlagsbuchhandlung, Stuttgart, Germany.
... The difficulties with the placement of some Paleozoic wingless insects is demonstrated by Carbotriplura kukalovae from the Pennsylvanian of the Czech Republic (Figure 3c), which was originally identified as a larva of Palaeoptera (Ephemerida) but later as a new suborder within "Thysanura" and ultimately attributed as belonging within Zygentoma or as a potential sister group to Pterygota (18,63,71,165,173) (Figure 2), a stunning range of phylogenetic placements. Quite critically, this fossil has been used as an outgroup to resolve phylogenetic relationships among palaeopteran insects, purportedly to improve the rooting of topologies (163). Given the uncertainty of its proper placement, such a calibration point for rooting or dating lacks credibility. ...
... Megasecoptera and Diaphanopterodea share a similar pattern of wing venation and body structures (22), which seems to suggest shared ancestry, although functional convergence has yet to be ruled out. The phylogeny of palaeopteran insects (163) resolved monophyly of Palaeodictyopterida, Megasecoptera, Diaphanopterodea, and Dicliptera (=Permothemistida), while Palaeodictyoptera was paraphyletic (Figure 2). Alternative, and somewhat radical, reclassifications do exist for the group (159) but are by no means cladistically founded. ...
While Mesozoic, Paleogene, and Neogene insect faunas greatly resemble the modern one, the Paleozoic fauna provides unique insights into key innovations in insect evolution, such as the origin of wings and modifications of postembryonic development including holometaboly. Deep-divergence estimates suggest that the majority of contemporary insect orders originated in the Late Paleozoic, but these estimates reflect divergences between stem groups of each lineage rather than the later appearance of the crown groups. The fossil record shows the initial radiations of the extant hyperdiverse clades during the Early Permian, as well as the specialized fauna present before the End Permian mass extinction. This review summarizes the recent discoveries related to the documented diversity of Paleozoic hexapods, as well as current knowledge about what has actually been verified from fossil evidence as it relates to postembryonic development and the morphology of different body parts.
... 5 Although the phylogenetic position of Palaeodictyoptera remains unresolved, they are certainly among the early diverging groups of Pterygota. 20 Here, we examine new material and revisit previously described species of palaeodictyopteran larvae and their exuviae to evaluate morphological characters on abdominal segments and to see what evidence can be obtained regarding putatively homologous structures with developing thoracic wings. Re-examinations of larvae of Bizarrea obscura from the Pennsylvanian of Mazon Creek (USA) and Rochdalia parkeri from the Late Carboniferous of the UK show the presence of two pairs of oblique thoracic wing pads and a pair of cordate structures laterally on the abdominal segments (I-IX), which are posteriorly broadly fused with their corresponding tergite, but also presumably articulated (hinged) medio-anteriorly. ...
The Late Paleozoic acquisition of wings in insects represents one of the key steps in arthropod evolution. While the origin of wings has been a contentious matter for nearly two centuries, recent evolutionary developmental studies suggest either the participation of both tergal and pleural tissues in the formation of wings1 or wings originated from exites of the most proximal leg podite incorporated into the insect body wall.2 The so-called “dual hypothesis” for wing origins finds support from studies of embryology, evo-devo, and genomics, although the degree of the presumed contribution from tergal and pleural tissues differ.3, 4, 5, 6 Ohde et al.,7 confirmed a major role for tergal tissue in the formation of the cricket wing and suggested that “wings evolved from the pre-existing lateral terga of a wingless insect ancestor.” Additional work has focused on identifying partial serially homologous structures of wings on the prothorax8,9 and abdominal segments.10 Thus, several studies have suggested that the prothoracic horns in scarab beetles,9 gin traps of tenebrionid and scarab beetle pupae,11,12 or abdominal tracheal gills of mayfly larvae1,13 evolved from serial homologues of wings. Here, we present critical information from abdominal lateral outgrowths (flaps) of Paleozoic palaeodictyopteran larvae, which show comparable structure to thoracic wings, consisting of cordate lateral outgrowths antero-basally hinged by muscle attachments. These flaps therefore most likely represent wing serial homologues. The presence of these paired outgrowths on abdominal segments I–IX in early diverging Pterygota likely corresponds to crustacean epipods14,15 and resembles a hypothesized ancestral body plan of a “protopterygote” model.
... Phylogenetic tree of Pterygota (combined fromSroka et al., 2015 andWipfler et al., 2019) with characters of gills mapped onto it (A) Condition without fossils discussed in this study. (B) Condition with fossils discussed in this study. ...
Aquatic larvae are known in three early branches of Pterygota: Ephemeroptera (mayflies), Plecoptera (stoneflies), and Odonata (dragonflies, damselflies). A common origin of these larvae has been suggested, yet also counterarguments have been put forward, for example, the different position of larval gills: laterally on the abdomen in Ephemeroptera, terminally in Odonata, variably in Plecoptera. We discuss recent fossil findings and report a new dragonfly-type larva from Kachin amber (Myanmar), which possesses ancestral characters such as a terminal filum, maintained in ephemeropterans, but lost in modern odonatan larvae. The new larva possesses lateral protrusions on the abdominal segments where in other lineages gills occur. Together with other fossils, such as a plecopteran retaining lateral gills on the abdomen, this indicates that lateral protrusions on the abdomen might have well been an ancestral feature, removing one important argument against the idea of an aquatic larva in the ground pattern of Pterygota.
... Ephemeroptera are an ancient order of insects with the earliest crown-group representatives known from the Lower Jurassic and the stem group even from the Late Palaeozoic (Prokop et al., 2010;Sroka et al., 2015). The life cycle of mayflies consists of an aquatic larval phase and terrestrial subimago and imago. ...
The numerous fossil specimens described as consecutive series of different larval stages of two species, Tchirkovaea guttata and Paimbia fenestrata (Palaeodictyoptera: Tchirkovaeidae), were reinvestigated with emphasis on comparing the development and growth of their wings with that of the wings of a recent mayfly, Cloeon dipterum. This unique fossil material was for a long time considered as undisputed evidence for an unusual type of wing development in Palaeozoic insects. The original idea was that the larvae of Palaeodictyopterida had wings, which were articulated and fully movable in their early stages of postembryonic development and that these gradually enlarging wings changed their position from longitudinal to perpendicular to the body axis. Moreover, the development of wings was supposed to include two or more subimaginal instars, implying that the fully winged instars moulted several times during their postembryonic development. The results of the present study revealed that there is no evidence that this series of nymphal, subimaginal and imaginal wings provide support for the original idea of wing development in Palaeozoic insects. On the contrary, our results indicate, that the supposed palaeodictyopteran larval wings are in fact wing pads with a wing developing inside the cuticular sheath as in recent hemimetabolous insects. Moreover, this study newly reinterpreted the wing pad base of Parathesoneura carpenteri and confirmed the presence of nygma like structures on wings and wing pads of palaeodictyopteran Tchirkovaeidae.
... The Permoplectoptera are the Palaeozoic stem group of modern mayflies (Ephemeroptera) and one of the most ancestral lineages within the pterygote insects, and as such, they are very important for understanding the early steps in the evolution of this speciose group of organisms. The Permoplectoptera forms a sister group to Heptabranchia, which consists of the stem group Coxoplectoptera (Lower Cretaceous) and the crown group Ephemeroptera [46]. ...
... An important character of the wing venation from a phylogenetic point of view is the costal brace (Figs. 2B, C; 3) as its presence is an apomorphy of Panephemeroptera sensu Sroka et al. [46]. The observed form of the costal brace in M. sharovi and M. zalesskyi is elongate and distinctly remote from the costal margin, with at least one crossvein connecting the costal brace to the costa, which is a plesiomorphic condition within the mayfly lineage [47]. ...
Background
The stem-group of Ephemeroptera is phylogenetically important for understanding key steps in evolutionary history of early pterygote insects. However, these taxa have been mostly studied from the taxonomy point of view focused on the pattern of wing venation and often using only classical optical microscopy devices. In-depth studies on detailed morphology of the different body structures are scarcely performed, although the results are critical for elucidation of life history traits and their evolutionary pattern among the basal pterygotes.
Results
New information is presented on the morphology of two species of Misthodotes , which are stem-mayflies from the Early Permian. Based on new results obtained from a re-examination of the type specimens and supplementary material, we infer the life history traits of both the adult and larval stages of these Palaeozoic insects and reconsider previous interpretations. For the first time, we report the structure of the thoracic pleura and the articulation at the base of the wing in a stem-group of Ephemeroptera and compare them with those of extant mayflies. We also provide additional support for the systematic placement of investigated taxa and an amended diagnosis of the genus Misthodotes .
Conclusions
Adult Misthodotes sharovi and Misthodotes zalesskyi had chewing mouthparts, which enabled them to scavenge or feed on plants. The wing apparatus was adapted for slow powered flapping flight and gliding, using long caudal filaments for steering. The wing base does not have rows of articulary sclerites as previously hypothesized for some Palaeozoic taxa but inflexible axilla similar to that found in modern mayflies. The structure of the thoracic pleura is also similar to that in the crown group of Ephemeroptera, while differences in the course of sutures may be explained by an evolutionary trend towards more powerful dorsoventral flying musculature and forewing-based flight (anteromotorism) in modern taxa. There is no evidence for swarming behaviour and mating in the air as occurs in modern mayflies as they had none of the associated morphological adaptations. Putative larvae of Misthodotes can not be unambiguously associated with the adults. They also exhibit some morphological specializations of Protereismatidae like 9 pairs of abdominal tracheal gills supporting their benthic lifestyle with legs adapted to burrowing.
... Sinitshenkova (2002: fig., p. 138) first proposed a phylogenetic hypothesis, but the absence of real outgroup(s) to basically polarise the character states, and the basal-most dichotomy established on the character ['wings wide basally' vs. 'wing base narrow'], with the two states supposedly supporting the two branches, while one should be plesiomorphic, prevent a total confidence to these results. Sroka et al. (2015: fig., p. 11) proposed another hypothesis, better supported by true outgroups and computer treatment of the data, in which the order Palaeodictyoptera falls as a grade, sister group of the (Megasecoptera + (Permothemistidae + Diaphanopterodea)). ...
A new dictyoneurid insect, Dictyoneura goujonorum n. sp. from the Latest Ghzelian-Asselian basin of Graissessac (Hérault, France) is described in details. It is represented by a well-preserved specimen with wings of 32-35 mm long and 13-14 mm wide and other peculiar diagnostic characters such an MP with four branches and a CuP with three branches. As all the other Dictyoneura species are known from the Namurian and/or the Wesphalian, Dictyoneura goujonorum n. sp. is the youngest representative of the genus. It is also the first record of the order Palaeodictyoptera from the Graissessac basin. The Carboniferous-Permian palaeodictyopterans are well-known to have lived in rather humid swamp forests. The global warming and drying of the climate during the Permian and/or the rise of potential predators may be responsible of their extinction.
