Corresponding author: Arnold H. Staniczek (
Academic editors: Ricardo Pérez-de la Fuente, Marianna Simões
The systematics of all known extant and fossil taxa of the mayfly family
The
The distribution of extant
Fossil taxa described in
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Holotype | Nymph | Crato Formation Brazil | Cretaceous Aptian approx. 113 Ma | ||
[The Crato Fossil Beds of Brazil: 182, fig. 11.6g; Fig. |
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[putative] Adult, sex unknown | Crato Formation Brazil | Cretaceous Aptian approx. 113 Ma | |||
[adult describedin here; Fig. |
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Holotype | Female imago | Baltic amber Europe | Eocene Lutetian 34–48 Ma | ||
[Stuttgarter Beitr. Naturk., Ser. B, 322: 7, figs 1–10] | |||||
Holotype | Male imago | Baltic amber Europe | Eocene Lutetian 34–48 Ma | ||
[Aquatic Insects, 31, Suppl. 1: 126, figs 1–5, Table |
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Holotype |
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Male subimago | Baltic amber Russian Federation | Eocene Lutetian 34–48 Ma | |
[described here; Figs |
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Paratype |
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Male subimago | Baltic amber Russian Federation | Eocene Lutetian 34–48 Ma | |
[described here; Fig. |
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Formally undescribed | NMVP103210 | Nymph | Koonwarra Fossil Bed Australia | Cretaceous Aptian 116±5Ma | |
[ |
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Formally undescribed | NMVP103209 | Nymph | Koonwarra Fossil Bed Australia | Cretaceous Aptian 116±5Ma | |
[ |
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Holotype | Adult male | New Jersey amber USA | Cretaceous Turonian 90 Ma | ||
[Studies on fossils in amber: 113, figs 1–5] | |||||
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Holotype |
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CNU-EPHMA2017001 | Female subimago | Burmese amber Myanmar | Cretaceous Albian 98.79±0.62 M |
[Cretaceous Research, 84: 402, figs 1–3] | |||||
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Holotype | Adult female | Burmese amber Myanmar | Cretaceous Albian 98.79±0.62 Ma | ||
[Bull. Nat. Hist. Mus. London, Geol. 56(1): 25, figs 1, 2] |
In this contribution, we describe
The holotype of
A–D:
The paratype of
The respective single nymphal and adult specimen of the Cretaceous species
Material preserved in Cretaceous limestones was examined in dry condition and under a film of ethyl alcohol using stereomicroscopes Olympus SZX7 and Leica M205 C. Drawings of amber specimens were made with a camera lucida on a Leica M205 C stereomicroscope. Serial photographs with different focal planes were taken through a Leica Z16 APO Macroscope equipped with a Leica DFC450 Digital Camera using Leica Application Suite v. 3.1.8. Resulting photo stacks were processed with Helicon Focus Pro 6.4.1 to obtain combined photographs with extended depth of field. Photographs were sharpened, and contrast and tonality were adjusted using Adobe Photoshop™ version 23.1.1 (Adobe Systems Incorporated, San Jose, USA). Measurements of individual body parts were taken either by using an ocular grid or inferred from the photographs taken with a calibration scale (see Table S1). Anatomical terminology is mainly based on
The electronic edition of this article conforms to the requirements of the amended International Code of Zoological Nomenclature, and hence the new names contained herein are available under that Code from the electronic edition of this article. This published work and the nomenclatural acts it contains have been registered in ZooBank, the online registration system for the ICZN. The ZooBank
In order to perform an integrated phylogenetic analysis of fossil and extant
The pieces of amber with embedded holotypes of
Modified after
Holotype: BaB 1373/1 in coll.
The species epithet refers to the shape of the paired subapical process of the penis, which is sharply pointed at the tip.
Male subimago (Figs
Male subimago (Figs
Colouration relatively pale, dirty yellow to light brown, except of fore- and hind wings distinctly darker, coloured brown to dark brown; distal half of left forewing intensively dark brown to blackish. Due to “Verlumung”, body colouration slightly frosted. Femora relatively pale, yellow to yellowish-brown; tibiae and tarsi darker than femora, up to brown, with blackish maculation irregularly scattered. Abdominal segments unicoloured, dirty brown to greyish brown, segments VII–X fully covered by “Verlumung”. Genitalia only visible ventrally, due to streaks and cracks of amber mainly from dorsal side; natural colouration of genitalia most probably not preserved.
Head. Eyes large, well developed, indistinctly separated into two portions; medially contiguous at short distance, flattened laterally; hexagonal ommatidia of upper portion of eyes well distinguishable; no preserved bands or strips on eyes laterally; ocelli poorly visible due to streaks and cracks, relatively small; antennae short, not longer than length of head; facial keel relatively large (Fig.
Penis lobes partly covered by “Verlumung”. Two-segmented forceps well preserved. Segment I long, moderately expanding distally, with widely rounded hump on inner margin; apically of hump indented, superficially giving the appearance of segmentation; after this indentation, segment I distinctly bent inwards at half-length, so forcipes tilted towards each other. Distal segment short, as long as 0.22–0.24 of segment I length, only laterobasally with clear segment border towards segment 1, tapering apically, with widely rounded tip. Penis lobes well separated by wide, V-shaped cleft; each lobe moderately tapered apically, rounded at tip; both lobes with prominent subapical process, sharply pointed at the tip (Figs
Male subimago (Figs
Despite some differences in body size of the specimens (see Table S1), we attribute both male subimagines described here to the single species
The new species described herein can be undoubtedly assigned to the genus
Like other taxa of
Up to now there was only a single male specimen of
A comparison of
Regarding body size, there remains the possibility that the described female of
Adult characters of
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Body length [mm] | 8.50 | 9.75 | 6.80–7.50 |
Forewings length [mm] | 9.80–10.10 | 11.60–11.75 | 8.30–10.5 |
Hind wings length [mm] | 3.50–3.55 | 3.55–3.60 | 2.30–2.75 |
Hind/Fore wings length ratio | 0.35 | 0.31 | 0.26–0.28 |
Forewings width/length ratio | 0.42 | 0.44 | 0.42–0.44 |
Hind wings width/length ratio | 0.23 | 0.26 | 0.26–0.28 |
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Eyes | small, well separated | large, contiguous medially | large, contiguous medially or separated by narrow gap |
Eyes [vertical bands] | absent | absent | absent |
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Prosternum [prominent bispinate projection] | present | present | present |
Mesonotal suture [scutellum] | elongate | elongate | elongate |
Mesothorax [anepisternum] | distinctly smaller than katepisternum | distinctly smaller than katepisternum | distinctly smaller than katepisternum |
Mesothorax [furcasternal protuberances] | contiguous | contiguous | contiguous |
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Wings [colouration] | unicolorous, no maculation | unicolorous, no maculation | unicolorous, no maculation |
Pterostigma [number of cross veins] | at least 15, dense row | 8 | 11–13 |
Pterostigma [shape of veins] | mainly branched | 1–2 forked, other unbranched | simple, unbranched |
RS furcation [respectively to vein length] | 0.18 | 0.13 | 0.13 |
0.54 | 0.56 | 0.56–0.58 | |
divergent | nearly parallel | nearly parallel | |
A1 [number of veins arising to basitornal margin] | 8–11 | 5–6 | 6–7 |
A1 [shape of veins arising to basitornal margin] | simple and forked veins | simple and forked veins | simple veins |
A1–A2 [number of cross veins] | 0 | 3–5 | 4–5 |
Intercalary veins between A1 and A2 | 6–10 | 1–2 | absent |
Intercalary veins between A2 and A3 | absent | 1–2 | 1 |
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Wing [shape] | nearly round | nearly round | nearly round |
Costal projection [shape] | moderately prominent; rounded | prominent; widely rounded apically | prominent; widely rounded apically |
C– |
5–8 | 4–5 | up to 12 |
C– |
simple | simple | simple and forked |
C– |
absent | absent | present |
Free short marginal intercalaries | present | present | present |
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Foretarsi [shape of claws] | dissimilar; one blunt, one pointed | both blunt | both blunt |
Abdomen | |||
Mid-dorsal transverse evaluation of tergum VI | present | present | present |
Sternum IX [in female] | without apical cleft | — | — |
Paracercus | vestigial | vestigial | vestigial |
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Forceps segment I [inner projection] | — | triangular | widely rounded |
Forceps segment II [shape] | — | nearly triangular | nearly conical |
Penis lobes [shape] | — | blunt apically | blunt apically |
Vicinity of Nova Olinda, southern Ceará state, northeast Brazil; upper Aptian, Lower Cretaceous, Nova Olinda Member, Crato Formation, Santana Group, Araripe Basin.
As for type species, since monotypic (see below); modified based on
Modified based on
Male nymph, holotype,
Length of body 8 mm [without terminal filaments]. Length of cerci 3 mm. The nymph was initially described by
Nymphs of (A, C, E)
Length of body 7 mm; length of forewing approximately 6 mm, maximum width 3.5 mm. Imago of unknown sex. Specimen preserved in right lateral view with both forewings overlapping. Except of forewings, entire body of specimen poorly preserved, first abdominal segments not discernible, only base of cerci preserved. Right forewing is almost complete except of cubital and anal fields with venation poorly distinguishable. Traces of left forewing venation partly overlapping with right forewing venation. Costal brace and basal part of costal field almost destroyed; longitudinal venation mostly preserved and distinguishable; cross veins poorly visible, especially in anal field. Hind wings partially superimposing forewings. Hind wing mostly damaged, with poorly preserved outline and trace of costal projection; venation almost lost. Legs completely missing, except of traces of putative trochanter of right and left foreleg. Because of poor preservation of eyes and lacking gonopods, the sex of this specimen is not determinable (Fig.
We opted not to include the two nymphs from the Lower Cretaceous of the Koonwarra Fossil Bed because there were only three character states to score, collapsing all branches into politomies. We have also excluded from the analysis the female holotype of
Strict consensus tree. Strict consensus of the one most parsimonious trees, from the analysis of 36 morphological characters from nymphs and adults of
Further characters prove the systematic position of
The adult of
Given its rarity within a site otherwise rich in fossil mayfly specimens,
Due to the presence of the massive notal shield and strong sclerotisation, nymphal
The putative adult specimen of
As expected,
The genus
Examination of the specimen by ourselves has not been possible despite our efforts. As a result, we could not investigate and code further characters like the presence or absence of the bispinate projection of the prosternum in
Two nymphs from the Lower Cretaceous of the Koonwarra Fossil Bed in Australia were reported by
The former placement can be additionally supported by the shape of their preserved forewing pads, which actually show remnants of venation. These show remarkable similarities to wings of
The systematic position of this taxon was unclear and only briefly commented on by
At the same time,
Nevertheless, a shortened antennal flagellum is only present in males of
In summary, none of the diagnostic criteria of
As Recent
RJG acknowledges the financial support of the Grant Agency of the Czech Republic (No. 21-05216S) and institutional support of the Institute of Entomology (Biology Centre of the Czech Academy of Sciences) RVO: 60077344. Acquisition of research equipment used in this study has been carried out within an equipment subsidy granted by Alexander von Humboldt Foundation [Georg Forster Research Fellowship for Experienced Researchers] to RJG. The stay of APS at
We are most grateful to Christel and Hans Werner Hoffeins (Hamburg) and to Mónica M. Solórzano-Kraemer (Senckenberg Forschungsinstitut und Naturmuseum, Frankfurt) for their support and loan of undescribed material. We also thank Milan Pallmann (
Figure S1
Figure S2
Table S1
Table S2
Table S3