A new mayfly subfamily sheds light on the early evolution and Pangean origin of Baetiscidae (Insecta: Ephemeroptera).

The family Baetiscidae Edmunds & Traver, 1954 is recognisable among mayflies due to its bizarre larvae, equipped with a robust and spiked thoracic notal shield covering part of the abdomen up to sixth segment. Originally being described as extant species from the USA and Canada, Baetiscidae were later found in the fossil record as well, specifically in Cretaceous of Brazil and Eocene Baltic amber. An enigmatic piece of fossil evidence are two larvae from the Early Cretaceous Koonwarra Fossil Bed in Australia, which have been presumed as attributable to Baetiscidae and briefly discussed in previous studies. In the present contribution, we reinvestigate these fossils and confirm their attribution to the family Baetiscidae. These larvae are depicted and described as Koonwarrabaetisca jelli gen. et sp. nov. and Koonwarrabaetisca duncani sp. nov. For both Cretaceous genera Protobaetisca Staniczek, 2007 and Koonwarrabaetisca gen. nov. we establish a new subfamily Protobaetiscinae subfam. nov. within the family Baetiscidae, based on the presence of markedly shortened thoracic sterna. The phylogenetic position of newly described subfamily is clarified using a cladistic analysis; Protobaetiscinae subfam. nov. forms a monophyletic clade, sister to Baetiscinae. The confirmation of the distribution of Baetiscidae in the Cretaceous of Australia suggests almost worldwide distribution of this family in the deep time. Given their limited dispersal abilities, this distributional pattern can be best explained by the Pangean origin for this family, moving the time of their origin at least to the Early Jurassic. The larvae of Koonwarrabaetisca gen. nov. exhibit the same ecomorphological specialization as the rest of Baetiscidae, that supporting with a high probability their lifestyle similar to extant Baetisca Walsh, 1862. The larvae probably lived in the flowing water with stony substrate densely covered by filamentous algae, and in the places of accumulation of dead plant and algae matter during the last instars. Thus, Koonwarrabaetisca gen. nov. could be the allochthonous component in mayfly fauna of the Koonwarra paleolake.

Baetidae (Insecta: Ephemeroptera) of Aurès Mountains (Algeria): A New Species of the Baetis alpinus Species Group, with Notes on Baetis Laech, 1815 Biogeography within Maghreb.

A new species, Baetis (Baetis) dihyaesp. nov., belonging to the Baetis alpinus species group, is described and illustrated based on larval material collected in the Aurès Mountains (northeastern Algeria) in 2020-2021. This new species is closely related to three European species, e.g., Baetis (B.) alpinus (Pictet, 1843); B. (B.) nubecularis Eaton, 1898; and B. (B.) pasquetorum Righetti & Thomas, 2002 by the combination of the following characteristics: (i) more than one short, stout bristle at the tip of segment II of the maxillary palp and (ii) a well-developed paracercus. However, the new species clearly differs from all congeners of the Baetis alpinus species group primarily by the (a) structure of mouthparts-with 14-18 long submarginal setae arranged in a single irregular row on the dorsal surface of the labrum; 2-6 short, stout bristles at the tip of segment II of the maxillary palp; and segment II of the labial palp without a considerably developed apico-internal lobe); (b) setation of abdominal terga, with a few triangular-shaped scales sparsely scattered near the posterior margin only; and (c) a well-developed paracercus, comprised of more than 50 segments. Primary data on the biology and distribution of this new species are provided, and molecular affinities are verified by the analysis of COI (barcode) sequences. Detailed notes on the distribution of mayfly species belonging to the Baetis alpinus species group common in Western Europe and the western part of North Africa are presented. The historical movement of Baetis representatives between Europe, North West Africa, and subsequently Algeria, with the land bridges 'Strait of Gibraltar' and 'Strait of Sicily' as colonization routes, is discussed in detail and identified in the present study as the Western Algeria colonization path and Eastern Algeria colonization path, respectively.

Fluctuation in the diversity of mayflies (Insecta, Ephemerida) as documented in the fossil record.

Due to their aquatic larvae, the evolution of mayflies is intricately tied to environmental changes affecting lakes and rivers. Despite a rich fossil record, little is known about the factors shaping the pattern of diversification of mayflies in deep time. We assemble an unprecedented dataset encompassing all fossil occurrences of mayflies and perform a Bayesian analysis to identify periods of increased origination or extinction. We provide strong evidence for a major extinction of mayflies in the mid-Cretaceous. This extinction and subsequent faunal turnover were probably connected with the rise of angiosperms. Their dominance caused increased nutrient input and changed the chemistry of the freshwater environments, a trend detrimental mainly to lacustrine insects. Mayflies underwent a habitat shift from hypotrophic lakes to running waters, where most of their diversity has been concentrated from the Late Cretaceous to the present.

A new Gondwanan mayfly family from the Lower Cretaceous Crato Formation, Brazil (Ephemeroptera: Siphlonuroidea: Astraeopteridae fam. nov.).

The adult holotype of the fossil mayfly Astraeoptera cretacica Brandão et al. 2021 from the Cretaceous Crato Formation, Brazil, is reviewed and attributed to a new family Astraeopteridae fam. nov. Based on alate specimens, we also describe further new representatives of Astraeopteridae fam. nov., namely Astraeoptera vitrea sp. nov. and Astraeoptera oligovenata sp. nov., as well as the new genus and species Eosophobia acuta gen. et sp. nov. A subsequent character analysis of the new material suggests systematic affinities of Astraeopteridae fam. nov. with those extant families of Siphlonuroidea distributed in the Southern Hemisphere. These newly described fossil Siphlonuroidea from the Cretaceous of Brazil thus add to the biogeography and systematics of mayflies.

The Tribe Hyrtanellini Allen, 1980 (Ephemeroptera: Ephemerellidae) of Western and Central Asia with Description of a New Species.

A new species, Serratella leonidi Martynov & Palatov, sp. nov., is described from Tajikistan based on immature stage. Based on larval material from Iran including the topotypes, Serratella elissa Jacobus, Zhou & McCafferty, 2009 is complementary described, and its generic placement is clarified. The delimitation of three genera that are members of the tribe Hyrtanellini Allen, 1980, namely Serratella Edmunds, 1959, Torleya Lestage, 1917 and Quatica Jacobus & McCafferty, 2008 is briefly discussed. The phylogenetic reconstruction of Hyrtanellini based on the COI gene showed the relations of representatives of these genera on the one hand, and distinct delimitation of Serratella leonidi sp. nov. and S. elissa on the other. A list of species from Western and Central Asia attributed to Hyrtanellini, their currently known distribution and a key for the determination of the larvae are proposed.

Present knowledge on Mecoptera of Ukraine.

The first annotated checklist of Mecoptera of Ukraine is presented. Altogether, 11 species of scorpionflies are known with a confirmed or probable occurrence in Ukraine. This list is based on previously published data, as well as on recently collected materials and specimens housed in the collection of the State Museum of Natural History NAS Ukraine, Lviv. This collection belongs to the oldest one in Ukraine and comprises specimens collected by Jzef Dzidzielewicz, the founder of mecopteran investigations in Eastern Europe in the 19th and 20th centuries. For each listed species, its distribution in Ukraine is given together with notes on the history of investigations, and synonymies of the respective taxa. Detailed information on the distribution of selected species from the Red Book of Ukraine is presented.

Cenozoic origins of the genus Calliarcys (Insecta, Ephemeroptera) revealed by Micro-CT, with DNA barcode gap analysis of Leptophlebiinae and Habrophlebiinae.

Mayflies (Ephemeroptera) are among the oldest pterygote insects, with the earliest fossils dating back to the Late Carboniferous. Within mayflies, Leptophlebiidae are a highly diverse and widespread group, with approximately 140 genera and 640 species. Whereas taxonomy, systematics, and phylogeny of extant Leptophlebiidae are in the focus of extensive studies, little is known about leptophlebiid fossil taxa. Because fossil remains of Ephemeroptera in sedimentary rocks are relatively rare, inclusions of mayflies in amber are a unique source of information on their evolution and diversity in the past. Leptophlebiidae found in Cenozoic resins mostly belong to the subfamilies Leptophlebiinae (in Eocene Baltic amber) and Atalophlebiinae (in Miocene Dominican and Mexican ambers). In the present contribution, we confirm the first finding of the genus Calliarcys from Eocene Baltic amber by using Micro-CT, which allowed confirming its generic placement by visualizing diagnostic key characters otherwise hidden by a cloud of turbidity. Additionally, we present first molecular data on the extant species Calliarcys humilis Eaton, 1881 from the Iberian Peninsula and the barcode gap analysis for Leptophlebiinae and Habrophlebiinae.

A new species of Epeorus (Caucasiron) (Ephemeroptera, Heptageniidae) from Azerbaijan and Iran.

A new species, Epeorus (Caucasiron) hyrcanicussp. nov., is described based on larval morphology and molecular data (COI) containing sequences from all Caucasian Caucasiron species described to date. The species is distributed in the Hyrcanian forest of southeastern Azerbaijan and northwestern Iran. Based on our wide-range sampling, the new species is likely endemic to this area. The most pronounced larval morphological diagnostic characters are the coloration pattern of abdominal sterna (a pair of oblique stripes and stripe-like medio-lateral maculae) and terga (triangular medial maculae), poorly developed projection of the costal margin of gill plates III, presence of hair-like setae on the surface of abdominal terga, and relatively wide shape of gill plates VII (in natural position from ventral view). The diagnostic characters are compared to related species, and primary information to habitat is provided.

Life history, systematics and flight ability of the Early Permian stem-mayflies in the genus Misthodotes Sellards, 1909 (Insecta, Ephemerida, Permoplectoptera).

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.

First fossil record of the mayfly family Vietnamellidae (Insecta, Ephemeroptera) from Burmese Amber confirms its Oriental origin and gives new insights into its evolution.

The small, monophyletic mayfly family Vietnamellidae Allen, 1984 has so far only been known from a few extant species of the genus Vietnamella Tshernova, 1972, which are all distributed in the Oriental Realm (Vietnam, Thailand, China, and India). Herein we report the first fossil record of Vietnamellidae based on a male and female imago from Mid-Cretaceous Burmese amber. We establish the new genus Burmella gen. nov. to accommodate these two new Mesozoic specimens. Their attribution to Vietnamellidae is supported by the rounded shape of the hind wings with arched outer margin, the course of thoracic sutures, and characteristics of venation, especially of MP and Cu of the forewings and associated intercalary veins of the cubital field. At the same time, Burmella gen. nov. clearly differs from Vietnamella by a diminished number of longitudinal and cross veins in the hind wings, and by the different shape of male genitalia. This first fossil record of Vietnamellidae supports an age of at least 100 Ma for this taxon.

Identification guide to larvae of Caucasian Epeorus (Caucasiron) (Ephemeroptera, Heptageniidae).

The Caucasus and adjacent areas are inhabited by fifteen species of mayflies of the genus Epeorus, subgenus Caucasiron Kluge, 1997 (Heptageniidae). This identification guide aims to facilitate an accurate species identification of their larvae and sum up all available information on their taxonomy and distribution. An identification key is provided, and the important diagnostic characters of all species are described and illustrated. The larva of E. (C.) insularis (Braasch, 1983) is described for the first time. This study enables the routine identification of Caucasiron larvae necessary for biomonitoring and hydrobiological research in the Caucasus region.

Diversity and distribution of Epeorus (Caucasiron) (Ephemeroptera, Heptageniidae) in Iran, with descriptions of three new species.

Combining morphological and molecular data in an integrative approach, three new mayfly species of Epeorus (Caucasiron) are described. These include Epeorus (Caucasiron) alborzicus Hrivniak & Sroka, sp. nov. and Epeorus (Caucasiron) shargi Hrivniak & Sroka, sp. nov. from northern Iran, and Epeorus (Caucasiron) zagrosicus Hrivniak & Sroka, sp. nov. from central Iran. They are unambiguously delimited using both distance-based and likelihood-based approaches in the analyses of barcode COI sequences. Each new species is compared with other species of the subgenus and morphological diagnostic characters are provided. Based on extensive sampling of streams throughout the country, the distribution and habitat preferences of all Caucasiron species in Iran are assessed. Altogether, there are now six species recorded, among them also E. (C.) nigripilosus Sinitshenkova, 1976 is reported for the first time in Iran. Five species are distributed in the Alborz Mts. in northern Iran, one species was found in the Zagros Mts. in central Iran.

Nomenclatural changes in Centroptella Braasch & Soldán, 1980 (Ephemeroptera, Baetidae).

The genus Centroptella Braasch & Soldán, 1980 is accepted here in a wide sense, i.e., including Chopralla Waltz & McCafferty, 1987. This genus concept is similar to the concept of the genus Bungona Harker, 1957 proposed by Salles et al. (2016), but with the generic name Centroptella instead of Bungona. The type species of Bungona, B. narilla Harker, 1957, has an unknown systematic position; the neotype designation proposed by Suter and Pearson (2001) is invalid, being inconsistent with the International Code of Zoological Nomenclature; the species name B. narilla and the generic name Bungona are nomina dubia, so the name Centroptella is the senior name for the genus under consideration. The generic names Chopralla and Crassolus Salles, Gattolliat & Sartori, 2016 both are junior synonyms of Centroptella (syn. nov.). The subgenera Bungona, Centroptella and Chopralla proposed by Salles et al. (2016) are unnatural. The following new combinations are proposed: Centroptella bintang (Marle, Salles & Gattolliat, 2016) comb. nov., Centroptella bifida (Shi & Tong, 2019) comb. nov., Centroptella fusina (Tong & Dudgeon, 2003) comb. nov., Centroptella fustipalpus (Lugo-Ortiz & McCafferty, 1998) comb. nov., Centroptella illiesi (Lugo-Ortiz & McCafferty, 1998) comb. nov., Centroptella inzingae (Crass, 1947) comb. nov., Centroptella papilionodes (Marle, Salles & Gattolliat, 2016) comb. nov., Centroptella pontica (Sroka, Godunko & Gattolliat, in Sroka et al. 2019) comb. nov., Centroptella ovata (Shi & Tong, 2019) comb. nov., Centroptella quadrata (Shi & Tong, 2019) comb. nov. and Centroptella saxophila (Agnew, 1961) comb. nov. The two Australian species, C. fustipalpus and C. illiesi, differ from each other in the shape of tergalii; corrections to the original description of C. fustipalpus are given based on re-examination of the holotype and paratypes; details of larval structures of C. illiesi are figured. Corrections to the former descriptions of the South African species C. inzingae and C. saxophila are given. Examination of type material led to the discovery that the original description of the Oriental species Centroptella liebenauae Soldán, Braasch & Muu, 1987 was based on two different species: the descriptions of imago and subimago belong to Centroptella longisetosa Braasch & Soldán, 1980 (the type species of Centroptella), and the description of larva belongs to a different species, which we describe here as Centroptella ingridae sp. nov. The holotype of C. liebenauae, a larva, should be considered lost; based on the date of collection, it belonged to C. longisetosa; a set of larval exuviae with the same collecting data as the holotype, is designated as the neotype of C. liebenauae, and a new synonymy is established: C. longisetosa = C. liebenauae syn. nov. The larvae originally assigned to C. liebenauae are placed to a new species Centroptella ingridae sp. nov. belonging to the inzingae-ingridae species group; all stages of development of this species are described based on male and female imagines reared from larvae in Thailand and on the misidentified paratypes of C. liebenauae from Vietnam. Centroptella longisetosa is redescribed based on the single paratype from China, the neotype and paratypes of C. liebenauae from Vietnam, and additional material from India. Additional data on the holotype of Centroptella colorata Soldán, Braasch & Muu, 1987 are given.

The impact of Miocene orogeny for the diversification of Caucasian Epeorus (Caucasiron) mayflies (Ephemeroptera: Heptageniidae).

A common hypothesis for the high biodiversity of mountains is the diversification driven by orogeny creating conditions for rapid in situ speciation of resident lineages. The Caucasus is a young mountain system considered as a biodiversity hotspot; however, the origin and evolution of its diversity remain poorly understood. This study focuses on mayflies of the subgenus Caucasiron, one of the most diversified stenotopic mayflies inhabiting various types of streams throughout the Caucasus. Using the time-calibrated phylogeny based on two mitochondrial (COI, 16S) and three nuclear (EF-1α, wg, 28S) gene fragments, we tested the role of Caucasian orogeny in biogeography, diversification patterns, and altitudinal diversification of Caucasiron mayflies. We found that orogeny promoted the lineage diversification of Caucasiron in the Miocene. The highest diversification rate corresponding with the uplift of mountains was followed by a significant slowdown towards the present suggesting minor influence of Pleistocene climatic oscillations on the speciation. The Caucasiron lineages cluster into three principal clades originating in the Upper Miocene. We found a strong support that one of the three clades diversified via allopatric speciation in the Greater Caucasus isolated in the Parathetys Sea. The other two clades originating most likely outside the Greater Caucasus diversified towards high and low altitude, respectively, indicating possible role of climatic factors and/or passive uplift on their differentiation. Current high Caucasiron diversity in the Greater Caucasus is a result of in situ speciation and later immigration from adjacent mountain ranges after the Parathetys Sea retreat. Our phylogeny supported the monophyly of Rhithrogeninae, Epeorus s.l., Caucasiron, and Iron. Epeorus subgenus Ironopsis was found paraphyletic, with its European representatives more closely related to Epeorus s.str. than to Iron. Therefore, we re-arranged taxa treated within Ironopsis to comply with the phylogeny recovered herein.

Revision of fossil Metretopodidae (Insecta, Ephemeroptera) in Baltic amber - Part 4: Description of two new species of Siphloplecton Clemens, 1915, with notes on the new S. jaegeri species group and with key to fossil male adults of Siphloplecton.

The Siphloplecton jaegeri species group is established here for three extinct species, namely for the earlier described Siphloplecton jaegeri Demoulin, 1968, and for two new species from Eocene Baltic amber, Siphloplecton landolti sp. nov. and Siphloplecton studemannae sp. nov. Based on the well-preserved specimens of these species, a diagnosis is provided for the newly established species group. Representatives of the S. jaegeri species group are characterized by the presence of large, medially contiguous eyes, stout pointed setae along the outer margin of the foretibia, three intercalaries in the cubital field of the forewing, and elongated penis lobes, which are apically triangular or rounded, medially contiguous, and with a V-shaped cleft apically. Further new specimens of the S. jaegeri species group are documented that cannot be attributed to species level due to their poor preservation. Finally, a key to male adults of fossil species of Siphloplecton is given.

New Oligoneuriidae (Insecta, Ephemeroptera) from Iran.

Two new species of the mayfly family Oligoneuriidae are described based on larval specimens recently collected in Iran. The first new species, Oligoneuriella tuberculata Godunko & Staniczek, sp. nov., can be distinguished from all its congeners by the presence of pronounced protuberances posteromedially on abdominal terga, highly reduced paracercus, large lamella of gill I, and setation on hind margin of middle and hind femora confined to their basal halves. The second species, Oligoneuriopsis villosus Bojková, Godunko, & Staniczek, sp. nov., remarkably belongs to a mostly Afrotropical genus. The new species clearly differs from all its congeners in the shape of setae on the surface of gills and terga, pattern of body colouration, and the shape of posterolateral projections of abdominal segments. Except for the species description, the generic diagnosis of Oligoneuriopsis Crass, 1947 is briefly discussed. COI barcode sequences of both new species are provided and molecular species delimitation is tested using distance-based and likelihood-based approaches, with both new species unambiguously recognised as separate lineages. The analysis of COI also corroborates the respective affinities of both new species, estimated based on morphology. The two new species of Oligoneuriidae described herein highlight the importance of the Middle East as a centre of diversity of this mayfly family within the Palaearctic.

Type material comparison of possible cryptic species of the genus Electrogena (Ephemeroptera, Heptageniidae) in Central Europe.

The genus Electrogena Zurwerra & Tomka, 1985 is a diverse mayfly group in the Western Palaearctic with a partially unclear taxonomy, even in well-examined areas such as Central Europe. Recently, one of the species belonging to this genus, Electrogenaujhelyii (Sowa, 1981), was identified as a complex of genetically and geographically separated species. Two other species, Electrogenasamalorum (Landa, 1982) and Electrogenarivuscellana Sartori & Landolt, 1991 were formerly stated as junior synonyms of the earlier species. The fact that the synonymy of E.samalorum and E.ujhelyii was stated without comparison of any larval or adult material and both species reportedly have different altitude preferences makes the taxonomical position of E.samalorum (and possibly E.rivuscellana) questionable. Among others, a comparison of type series is one of the first methods that should be used to clarify the taxonomical position of closely related taxa. The present study aims to comparatively examine the type material and topotypes of E.ujhelyii and its presumed junior synonym E.samalorum for the first time in detail. Additionally, some notes on the status of the geographically extralimital E.rivuscellana are discussed briefly. We noted a significant similarity of all studied material from both the larval and imaginal stages, and suggest considering both junior synonyms (E.samalorum and E.rivuscellana) as species inquirendae.

A new Epeorus (Caucasiron) (Ephemeroptera: Heptageniidae) species from Turkey based on molecular and morphological evidence.

Epeorus (Caucasiron) turcicus sp. nov. is described based on larvae from NE Turkey. The new species can be distinguished from other Caucasiron by a unique combination of several diagnostic characters: the presence of a rounded hypodermal medial femur spot, colouration of abdominal terga and sterna, narrow gill plate VII, fine hair-like setae on the surface of abdominal terga, and absence of postero-lateral projections on tergum X. In addition to morphological analysis, two single-locus analytical approaches are employed for delimiting the new species using COI sequences (Automatic Barcode Gap Discovery, ABGD; and General Mixed Yule Coalescent Model, GMYC). Both approaches unambiguously recognized E. (C.) turcicus sp. nov. as a distinct species. Our molecular dataset contains all Caucasiron species occurring in the Caucasus and the delimitation of individual species mostly follows the morphologically defined species. This study confirms the suitability of the GMYC approach for species delimitation within Caucasiron.

Diversity of Armenian mayflies (Ephemeroptera) with the description of a new species of the genus Ecdyonurus (Heptageniidae).

We provide the first commented checklist of Armenian mayflies, based on all relevant literature and recent extensive sampling of 72 localities throughout Armenia during 2011, 2014, and 2015. Altogether 46 species are listed, eight of them reported from Armenia for the first time. One new species, Ecdyonurus (Ecdyonurus) eurycephalus sp. nov. is described (larva and male imago) based on morphological and molecular (COI) data. The species is characterized by a unique head shape in male imago and by the presence of tracheal filaments on gill plate VII in the larval stage.