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The genus Ulmeritoides includes 20 species, of which nine are known only from the adult forms, with the nymphal stage yet to be described. Moreover, over half of the species are known from very few records, often limited to their type-localities and nearby areas. This situation reflects the current state of knowledge gaps in Neotropical leptophlebiids, particularly the Linnean, Wallacean, and Haeckelian shortfalls, which are the most significant challenges in understanding biodiversity. This study aims to address some of these gaps by describing a new species, Ulmeritoides rebousas sp. nov. based on stage association of nymph, male and female imagos. Additionally, the nymphal stage of U. spinulipenis is described for the first time. Both species were collected in the Iguaçu National Park, Paraná state, Brazil. These findings represent the first record of Ulmeritoides spinulipenis in Brazil and, together with Ulmeritoides rebousas sp. nov., they mark the first occurrence of the genus Ulmeritoides in Paraná State. Furthermore, this study provides an updated identification key for the genus Ulmeritoides based on nymphs and male imagos. [ABSTRACT FROM AUTHOR]

Climate change, with the disruption of hydrological and thermal regimes, is threatening freshwater entomological biodiversity in different ways. While extinction or distribution range change of some species can be noted relatively easily, the effects on life cycle usually require considerable data. In this short communication, we show that Ephoron virgo (Olivier, 1791), a univoltine mayfly, anticipated the date of emergence in the Tanaro River (Northwest Italy) over the last 17 years and how this is closely related to the increase in local temperatures. Since this species is known for its impressive and synchronised hatchings, we relied on official reports from the municipality of Alba, which allowed us to analyse a greater dataset, demonstrating how unconventional documents combined with direct observation or press articles can also be useful in scientific studies. [ABSTRACT FROM AUTHOR]

The diversity of a mayfly genus, Drunella Needham (Ephemeroptera: Ephemerellidae), was examined using relationships of the barcode region of the cytochrome c oxidase subunit I (cox1) gene. Two novel species, Drunella campicola Ishiwata sp. nov. and Drunella parvicarnivora Ishiwata sp. nov. were described and Drunella cryptomeria was redescribed. A cox1 dendrogram based on the maximum likelihood method consisted of 10 clusters of DNA sequences sampled in Japan, which were roughly divided into three groups. The first group comprised D. cryptomeria and the two newly described species (D. campicola and D. parvicarnivora), the second group included D. basalis and D. ishiyamana, and the third group comprised D. trispina, D. triacantha, D. kohnoi, and D. sachalinensis. A cryptic lineage of D. trispina was observed and the distance between the two D. trispina clades is comparable to that between D. triacantha and each of the two D. trispina clades. The inheritance of the mitochondrial genome in these species is yet unclear, and therefore needs to be studied further. In the present study, we were able to confirm the distinct lineages based on cox1 and aided in the understanding of the taxonomy of the genus Drunella with descriptions of two new species. [ABSTRACT FROM AUTHOR]

Previously, no adult of the Asian Prosopistomatidae had been reported despite that this region has over half species of the family. Similarly, while six species have been discovered in China, they have never been systematically compared. In this study, we provide detailed photos of all Chinese Mainland species, including a new one named Prosopistoma wuchang sp. nov. In nymphs, the new species has a flat body and a distinct carapace color pattern. In adults, it exhibits clear sexual dimorphism in both color and structure. Males can be recognized by unnotched posterior flange of imaginal head, U-shaped median notch of imaginal penes and hooked claw of subimagos. Females can be recognized by uniformly brown body, non-branching veins of hindwings, postero-lateral projections of abdominal segments and the white filament arising from mesonotum. Taxonomically, this new species represents the first known adult from Asia and the first nymph-adult association via molecular sequences. Biologically, the nymphs of this new species live in the rapid currents of a wide river in southwestern China, while the adults emerge at dawn. [ABSTRACT FROM AUTHOR]

The evolution of insects has been marked by the appearance of key body plan innovations that promoted the outstanding ability of this lineage to adapt to new habitats, boosting the most successful radiation in animals. To understand the evolution of these new structures, it is essential to investigate which genes and gene regulatory networks participate during the embryonic development of insects. Great efforts have been made to fully understand gene expression and gene regulation during the development of holometabolous insects, in particular Drosophila melanogaster. Conversely, functional genomics resources and databases in other insect lineages are scarce. To provide a new platform to study gene regulation in insects, we generated ATAC-seq for the first time during the development of the mayfly Cloeon dipterum, which belongs to Paleoptera, the sister group to all other winged insects. With these comprehensive datasets along six developmental stages, we characterized pronounced changes in accessible chromatin between early and late embryogenesis. The application of ATACseq in mayflies provides a fundamental resource to understand the evolution of gene regulation in insects. [ABSTRACT FROM AUTHOR]

Simple Summary: Heptageniidae is the third most species-rich family within Ephemeroptera (mayflies). Although multiple studies have been conducted, the monophyly, phylogenetic relationships, and the divergence time of its subfamilies have always been controversial. The current study sequenced 17 new mitogenomes to reconstruct the phylogenetic relationships and calculate the divergence time within Heptageniidae. Therefore, based on comparing the composition of three mitogenomes bias, phylogenetic relationships, and divergence time of Epeorus montanus Brodsky, 1930, we suggest that cryptic species exist in E. montanus. Heptageniidae are known for their flat heads and bodies and are divided into three subfamilies. Despite the extensive diversity within this group and considerable efforts made to understand their evolutionary history, the internal classifications and origin time of Heptageniidae remains controversial. In this study, we newly sequenced 17 complete mitogenomes of Heptageniidae to reconstruct their phylogenetic positions within this family. Because of the ambiguous time of origin, our study also estimated the divergence time within Heptageniidae based on five fossil calibration points. The results of BI and ML trees all highly supported the monophyly of Heptageniidae and three subfamilies. The phylogenetic relationship of Rhithrogeninae + (Ecdyonurinae + Heptageniinae) was also recovered. The divergence time showed that Heptageniidae originated from 164.38 Mya (95% HPD, 150.23–181.53 Mya) in the mid-Jurassic, and Rhithrogeninae originated from 95.54 Mya (95% HPD, 73.86–120.19 Mya) in the mid-Cretaceous. Ecdyonurinae and Heptageniinae began to diverge at 90.08 Mya (95% HPD, 68.81–113.16 Mya) in the middle Cretaceous. After morphological identification, analysis of the mitogenome's composition, genetic distance calculation, phylogenetic analysis, and divergence time calculation, we suggest that two different populations of Epeorus montanus collected from Aksu, Xinjiang Uygur Autonomous Region (40°16′ N, 80°26′ E) and Xinyuan, Xinjiang Uygur Autonomous Region (43°20′ N, 83°43′ E) in China are cryptic species of E. montanus, but further detailed information on their morphological characteristics is needed to fully identify them. [ABSTRACT FROM AUTHOR]

We modeled feeding of the Atlantic salmon (Salmo salar) parr to understand the role of global (cross‐continental) and regional (river) spatial scales for delineating feeding patterns. The diet composition differed between Eurasia and North America populations. Geographic location (latitude and elevation) had an influence for the most common prey (Ephemeroptera, Diptera and Plecoptera). The random factors (sampling location and river) had a strong explanatory power in our models, suggesting that local drivers may override the effects of large‐scale drivers. [ABSTRACT FROM AUTHOR]

Large rivers are difficult to sample due to their size yet critical to monitor because humans heavily rely upon and alter them. Aquatic invertebrates are commonly used to assess the ecosystem quality of streams, but methods to sample large rivers are underdeveloped. We sampled aquatic invertebrates using a Hess sampler and rock baskets in the Snake River near Jackson, Wyoming, USA. Hess samples collected more aquatic invertebrate taxa and a higher proportion of Ephemeroptera, Plecoptera, and burrowing taxa. Rock baskets collected a higher proportion of Trichoptera, filterers, and clinging taxa. Bioassessment metrics differed between sampling methods; richness, diversity, evenness, Ephemeroptera, Plecoptera, and Trichoptera (EPT), and Hilsenhoff's biotic index produced higher values in Hess samples, and percent EPT was higher in rock baskets. Non-metric multidimensional scaling and analysis of similarity indicated that the samplers collected different assemblages (p < 0.001). The standard error of total invertebrate density was smaller and most taxa were collected with seven replicate samples. Understanding how sampling methods alter the aquatic invertebrates collected will help managers develop monitoring protocols that are best suited to the river and collect the most unbiased invertebrate assemblages. [ABSTRACT FROM AUTHOR]

So far, species of the genus Isonychia Eaton, 1871 have been reported to have transparent or partially pigmented wings, particularly their hindwings. A new species, I. fuscimarginata sp. n., recently collected from southern China, shows a different case. Both its forewings and hindwings have striking reddish brown to chocolate margins and stripes. Besides that, the entirely dark brown forelegs, shortened but apically widened male penises, and the colour and spine patterns of nymphal gills are useful characters for identification. This new species enriches the colour pattern of the genus Isonychia and the family Isonychiidae. [ABSTRACT FROM AUTHOR]

We identified groups of mayfly species that share microhabitats in eastern Cuban streams by sampling during rainy and dry seasons in four microhabitats in pools (cobbles, sand, leaf litter and bank vegetation) and one microhabitat (cobbles) in riffles. A total of 20 species and three morphospecies were found. Species similarity in habitat use was analysed using k-means clustering. Overall, the highest number of individuals was collected in cobbles in riffles, followed by cobbles in pools. Five species groups, labelled from I to V, were identified based on their primary microhabitat use. Two groups (I and V) included species with a generalist pattern of habitat use, but differing in seasonality. Species in remaining groups tend to concentrate in specific microhabitats. Species of groups II and IV use mostly cobbles in riffles and in pools, respectively, while species in group III concentrate in sand during the rainy season. Our results allowed to identify the species most vulnerable to alterations of the hydrologic regimen. [ABSTRACT FROM AUTHOR]

The mayfly Ephemera lota Navás, 1934 was described based on subimagines, and the imagines and nymphs have not been known so far. For the first time, we provide descriptions of adults and nymphs using recently collected material. Based on their morphology, the species diagnostic characters are imaginal abdomen without transverse line, penis with finger-like apex, hindwing without any dot; nymphal frons with deep anterior emargination, two mandibular tusks subequal in length. Significantly, forewings of this species have variable MP2 base: from independent to fusing with CuA in different specimens through the other characters and barcoding data confirm all specimens belong to the same species. Due to the holotype lost, a neotype of the species is designated and subimagines are re-described. [ABSTRACT FROM AUTHOR]

Mayflies, recognized for their hemimetabolous life cycle and ephemeral adult phase, exhibit diverse larval forms categorized as burrowing, flattened, swimming, and creeping. Ameletus inopinatus Eaton, 1887, a member of the Ameletidae family within the order Ephemeroptera, undergoes aquatic development and is commonly found in the tranquil stretches of small rivers or streams, particularly among stones and boulders. This study focused on A. inopinatus nymphs collected from Yarımca village in Eskişehir, Turkiye. Employing molecular techniques and culture-independent methods, rRNA-based analyses were conducted to characterize the archaeal and bacterial communities within the nymphs' gut. Microbial DNA was extracted from the gut, and PCR amplification targeted 16S rRNA genes for both Archaea and Bacteria domains. Denaturing gradient gel electrophoresis (DGGE) separated the amplified products, yielding six distinct bands with Bacteria-specific primers. The subsequent analysis of 16S rRNA sequencing from DGGE bands revealed a predominance of the Proteobacteria phylum within the gut lumen. Complementary investigations into prokaryotic diversity employed fluorescence in situ hybridization (FISH) and 4',6-diamidino-2-phenylindole (DAPI) staining. Total DAPI cell counts indicated a microbial cell population of approximately 106 ± 0.18 in the samples. The overarching conclusion derived from these findings is that the microbial community within the Ameletus inopinatus gut is predominantly associated with the Bacteria domain. Recognizing the ecological importance of this symbiotic relationship, the coexistence of mayflies with specific microbial communities is emphasized, underscoring the potential mutualistic roles played by these microorganisms in the life cycle and ecological dynamics of Ameletus inopinatus. This research not only contributes valuable insights into the microbial ecology of mayfly nymphs but also underscores the significance of understanding the intricate relationships between insects and their associated microorganisms for broader ecological perspectives and potential applications in environmental management. [ABSTRACT FROM AUTHOR]

Excess fine sediment (particles <2 mm) delivery and deposition in freshwater systems is a significant factor in structuring aquatic communities and populations.Invertebrate gill surfaces can become covered with fine sediment, potentially compromising osmoregulatory function.Ionocytes are specialised structures for osmoregulation found on the tracheal gills of mayflies. The number of cells has been shown to change in order to maintain osmoregulatory demands under environmentally variable conditions.To investigate whether ionocytes vary in response to fine sediment pressure, individuals of Baetis rhodani were collected from two high and low fine sediment cover sites, respectively, in the UK. Tracheal gills were subsequently examined for the number of ionocytes present on the upper and lower gill surfaces, standardised by gill size.Results indicated that the number of ionocytes was significantly higher for mayflies collected from areas with high fine sediment cover. High fine sediment sites were also characterised by lower altitude and dissolved oxygen concentrations. Mayfly gills collected from high sediment cover sites were also significantly larger than those collected from low sediment sites.The results illustrate the potential for mayfly larvae to demonstrate phenotypic plasticity to the pressures associated with fine sediment but that these responses are likely dependent on the composition of fine sediment deposits (organic or mineral) and associated oxygen concentrations. [ABSTRACT FROM AUTHOR]

Caenis ulmeriana Malzacher, 2015 is recorded for the first time from the Western Ghats, India. Prior records of this species encompass Java, Sumatra, Thailand, Myanmar, and the Philippines. Notably, the Indian population of C. ulmeriana showcases variability, including slight changes in the shape of forceps in the male subimago and increased denticulation in the midclaw, a reduced number of setae in the Y-ridge of tergalius II, and differing shape of sternum IX in the larvae compared to other continental and island populations. The species number of Caenis Stephens, 1835 has now increased to twelve in India. A distributional map detailing the range of C. ulmeriana in the Oriental region is also provided herein. [ABSTRACT FROM AUTHOR]

Mayflies (Ephemeroptera) are among the crucial water and habitat quality bioindicators. However, despite their intensive long‐term use in various studies, more reliable mayfly DNA barcode data have been produced in a negligible number of countries, and only ~40% of European species had been barcoded with less than 50% of families covered. Despite being carried out in a small area, our study presents the second‐most species‐rich DNA reference library of mayflies from Europe and the first comprehensive view from an important biodiversity hotspot such as the Western Carpathians. Within 1153 sequences, 76 morphologically determined species were recorded and added to the Barcode of Life Data System (BOLD) database. All obtained sequences were assigned to 97 BINs, 11 of which were unique and three represented species never barcoded before. Sequences of 16 species with high intraspecific variability were divided into 40 BINs, confirming the presence of cryptic lineages. Due to the low interspecific divergence and the non‐existing barcoding gap, sequences of six species were assigned to three shared BINs. Delimitation analyses resulted in 79 and 107 putative species respectively. Bayesian and maximum‐likelihood phylogenies confirmed the monophyly of almost all species and complexes of cryptic taxa and proved that DNA barcoding distinguishes almost all studied mayfly species. We have shown that it is still sufficient to thoroughly investigate the fauna of a small but geographically important area to enrich global databases greatly. In particular, the insights gained here transcend the local context and may have broader implications for advancing barcoding efforts. [ABSTRACT FROM AUTHOR]

The genus Isonychia Eaton, 1871 is widely distributed across the Holarctic and Oriental regions. However, no representatives of this genus have been reported from southwestern China, a region known for its high biodiversity. Here, we described and illustrated Isonychia latias sp. nov., a new species recently collected from Guizhou Province, southwestern China, across all developmental stages. The imagos of this new species exhibit some uncommon characters within Isonychia, such as brown mid- and hindlegs, and pale stripes on the thorax. To explore the phylogenetic status of this new species within Isonychia, a multigene phylogenetic analysis was conducted. [ABSTRACT FROM AUTHOR]

Rapid changes in thermal environments are threatening many species worldwide. Thermal acclimatisation may partially buffer species from the impacts of these changes, but currently, the knowledge about the temporal dynamics of acclimatisation remains limited. Moreover, acclimatisation phenotypes are typically determined in laboratory conditions that lack the variability and stochasticity that characterise the natural environment. Through a distributed lag non‐linear model (DLNM), we use field data to assess how the timing and magnitude of past thermal exposures influence thermal tolerance. We apply the model to two Scottish freshwater Ephemeroptera species living in natural thermal conditions. Model results provide evidence that rapid heat hardening effects are dramatic and reflect high rates of change in temperatures experienced over recent hours to days. In contrast, temperature change magnitude impacted acclimatisation over the course of weeks but had no impact on short‐term responses. Our results also indicate that individuals may de‐acclimatise their heat tolerance in response to cooler environments. Based on the novel insights provided by this powerful modelling approach, we recommend its wider uptake among thermal physiologists to facilitate more nuanced insights in natural contexts, with the additional benefit of providing evidence needed to improve the design of laboratory experiments. [ABSTRACT FROM AUTHOR]

Branchiobaetis Kaltenbach, Kluge & Gattolliat, 2022 and Megabranchiella Phlai-ngam & Tungpairojwong, 2022 (Ephemeroptera: Baetidae) are newly recorded in China. Two new species, Branchiobaetis borealis sp. nov. based on larval stage and Branchiobaetis megasinus sp. nov. based on larval and imaginal stages associated by laboratory rearing, are described. Megabranchiella longusa Phlai-ngam & Tungpairojwong, 2022, previously only distributed from Thailand, is recorded from China for the first time. [ABSTRACT FROM AUTHOR]

Miroculis (Ommaethus) Savage and Peters, 1983 (Ephemeroptera, Leptophlebiidae) is reviewed based on fresh material from Southeastern Brazil and on type specimens. Miroculis (Ommaethus) cipoensis sp. n. is described based on male and female imagos from Serra do Cipó, Minas Gerais State, Brazil. It can be distinguished from other species of the subgenus based on the following characteristics: forewings with membrane brown and dark brown mark around cross veins; hind wing uniformly brown; forceps segment I light brown, segment II and III lighter; penis lobe long (at least ⅔ of forceps segment I) and apically rounded and curved on apical ¼; length of body between 5.0 and 6.3 mm. Photographs of fresh material belonging to M. (O.) froehlichi Savage and Peters, 1983 and M. (O.) mourei Savage and Peters, 1983 are provided, clarifying the boundaries between the existing species of the subgenus. Based on that, M. (O.) misionensis Domínguez, 2007 is considered a junior synonym of M. (O.) mourei. A key to the male imagos of the subgenus is presented, as well as a distributional map with updated records of the species. [ABSTRACT FROM AUTHOR]

Rapid changes in thermal environments are threatening many species worldwide. Thermal acclimatisation may partially buffer species from the impacts of these changes, but currently, the knowledge about the temporal dynamics of acclimatisation remains limited. Moreover, acclimatisation phenotypes are typically determined in laboratory conditions that lack the variability and stochasticity that characterise the natural environment. Through a distributed lag non‐linear model (DLNM), we use field data to assess how the timing and magnitude of past thermal exposures influence thermal tolerance. We apply the model to two Scottish freshwater Ephemeroptera species living in natural thermal conditions. Model results provide evidence that rapid heat hardening effects are dramatic and reflect high rates of change in temperatures experienced over recent hours to days. In contrast, temperature change magnitude impacted acclimatisation over the course of weeks but had no impact on short‐term responses. Our results also indicate that individuals may de‐acclimatise their heat tolerance in response to cooler environments. Based on the novel insights provided by this powerful modelling approach, we recommend its wider uptake among thermal physiologists to facilitate more nuanced insights in natural contexts, with the additional benefit of providing evidence needed to improve the design of laboratory experiments. [ABSTRACT FROM AUTHOR]

The eight northeastern Nearctic species of Rhithrogena are principally known from descriptions of male imagos. Nymphs of several species (R. amica, R. anomala, R. brunneotincta, and R. gaspeensis) remain undescribed and existing keys are incomplete or regionally restricted. The inability to accurately determine nymphs of the northeastern species of Rhithrogena has been a long-standing problem for ecologists, aquatic biomonitoring programs, efforts to monitor effects of climate on sensitive aquatic taxa, and now efforts to assess conservation needs of aquatic insect species. Nymphs of all northeastern species of Rhithrogena (except for that of R. gaspeensis, which remains unknown) are either described for the first time or redescribed in a fully comparative manner. Diagnoses for each species and a new illustrated key to late instar nymphs are presented. Two major taxonomic outcomes are: (1) clarification of the taxonomic status of R. jejuna Eaton s.s. and subsequent recognition of R. undulata (Banks) as a new subjective junior synonym of R. jejuna Eaton s.s.; and (2) recognition of a new species (R. serpenglena sp. n.) that was previously incorrectly identified as R. jejuna Eaton. Lastly, new distribution records, information on species ranges, and notes of aquatic habitats of nymphs are also presented. [ABSTRACT FROM AUTHOR]

Three new fossil mayfly (Ephemeroptera) larvae from the Redmond Formation (Cenomanian) of Newfoundland and Labrador, Canada, are described: Alatuscapillus icarus gen. et sp. nov. (family Oligoneuriidae), Cruscolli sheppardae gen. et sp. nov. (family Heptageniidae), and Protoligoneuria borealis sp. nov. (family Hexagenitidae). This discovery marks the first juvenile insect nymphs to be described from this formation and helps fill gaps in our understanding of the global and temporal distribution of mayflies during the Cretaceous period. Of these, C. sheppardae marks the oldest occurrence of the family Heptageniidae in the fossil record, while A. icarus and P. borealis mark the first fossil occurrences of the families Oligoneuriidae and Hexagenitidae in North America. The anatomy, preservation, and behaviour of these new mayfly species inferred from modern taxa consolidate the hypothesis that the Redmond Formation's palaeoenvironment was lacustrine in nature. [ABSTRACT FROM AUTHOR]

Branchiobaetis Kaltenbach, Kluge & Gattolliat, 2022 and Megabranchiella Phlai-ngam & Tungpairojwong, 2022 (Ephemeroptera: Baetidae) are newly recorded in China. Two new species, Branchiobaetis borealis sp. nov. based on larval stage and Branchiobaetis megasinus sp. nov. based on larval and imaginal stages associated by laboratory rearing, are described. Megabranchiella longusa Phlai-ngam & Tungpairojwong, 2022, previously only distributed from Thailand, is recorded from China for the first time. [ABSTRACT FROM AUTHOR]

As part of our detailed study of the Caucasian mayfly fauna, we describe Epeorus (Caucasiron) abditus sp. nov., a new species of the genus Epeorus Eaton, 1881, subgenus Caucasiron Kluge, 1997, based on larvae collected in Türkiye, Georgia, and Russia. We use several methodological approaches to delimit the new species by analysing COI sequence data and larval morphology. We provide a comparison with related taxa and diagnostic characters allowing determination of the larvae. We also update the identification key for the Caucasian species of E. (Caucasiron) with E. (C.) abditus sp. nov. and two recently described species, E. (C.) hyrcanicus Hrivniak & Sroka, 2021 and E. (C.) tripertitus Hrivniak & Sroka, 2022. [ABSTRACT FROM AUTHOR]

Simple Summary: As one of the burrowing mayfly groups with large mandibular tusks, the phylogenetic relationships within Potamanthidae are always controversial. There are at least two opposite hypotheses for mayfly grouping: Potamanthidae + (Ephemeridae + Polymitarcyidae) and (Potamanthidae + Ephemeridae) + Polymitarcyidae. Because of the indeterminate origin time of this group, the present study aimed to reconstruct the phylogenetic relationship and explore the origin time of Potamanthidae based on mitochondrial (mt) genomes. In addition, the protein-coding genes (PCGs) of these mt genomes may undergo positive selection when these species live in low-temperature environments. Potamanthidae belongs to the superfamily Ephemeroidea but has no complete mt genome released in the NCBI (except for two unchecked and one partial mt genome). Since the sister clade to Potamanthidae has always been controversial, we sequenced seven mt genomes of Potamanthidae (two species from Rhoenanthus and five species from Potamanthus) in order to rebuild the phylogenetic relationships of Potamanthidae in this study. The divergence time of Potamanthidae was also investigated by utilizing five fossil calibration points because of the indeterminate origin time. In addition, because Rhoenanthus coreanus and Potamanthus luteus are always in low-temperature environments, we aimed to explore whether these two species were under positive selection at the mt genome level. Amongst the 13 PCGs, CGA was used as the start codon in COX1, whereas other genes conformed to initiating with an ATN start codon. From this analysis, UUA (L), AUU (I), and UUU (F) had the highest usage. Furthermore, the DHU arm was absent in the secondary structure of S1 in all species. By combining the 13 PCGs and 2 rRNAs, we reconstructed the phylogenetic relationship of Potamanthidae within Ephemeroptera. The monophyly of Potamanthidae and the monophyly of Rhoenanthus and Potamanthus were supported in the results. The phylogenetic relationship of Potamanthidae + (Ephemeridae + Polymitarcyidae) was also recovered with a high prior probability. The divergence times of Potamanthidae were traced to be 90.44 Mya (95% HPD, 62.80–121.74 Mya), and the divergence times of Rhoenanthus and Potamanthus originated at approximately 64.77 Mya (95% HPD, 43.82–88.68 Mya), thus belonging to the late Pliocene Epoch or early Miocene Epoch. In addition, the data indicated that R. coreanus was under negative selection and that ATP8 and ND2 in Potamanthidae had a high evolutionary rate. [ABSTRACT FROM AUTHOR]

Cincticostella jianchuan sp. nov. from Dali Bai Autonomous Prefecture, Yunnan Province, China, is described based on chorionic structure, nymph, and winged stages. The new species is closely related to C. fusca (Kang & Yang, 1995), but it can be distinguished in the male imago stage by its mesonotum and penes morphology, coloration, and the forking point of the stem of MA+Rs on the forewing; in the nymph stage, it can be distinguished by the length of the posterolateral projections of abdominal segment IX and the setation of the abdominal terga. Compared to other congeners, nymphs and male imagoes of the new species and C. fusca share several morphological characteristics, such as a larger body, mesothorax with medially notched anterolateral projections, forefemur without a subapical band of transverse spines of the nymphs, the area between C, Sc and R1 of the forewings distinctly pigmented, and an apical sclerite on the ventral face of the penes of the male imagoes, supporting the proposition of a new species complex, the jianchuan complex. The systematics of Cincticostella and related genera are discussed briefly. [ABSTRACT FROM AUTHOR]

The State of Maranhão, located in northeastern Brazil, has a great biodiversity due to the complex of biomes that constitutes its territory. Due to the paucity of research in the area, there are gaps in knowledge of the local fauna. This work aims to contribute to the knowledge of the order Ephemeroptera. Two species of Baetidae, Callibaetis nigracyclus (Cruz et al. J Nat Hist 48:591–660, 2014) and Cloeodes auwe (Salles et al. Biota Neotrop 4:1–8, 2004a), and one species of Leptophlebiidae, Hermanella mazama (Nascimento, Mariano and Salles, 2012) are here registered from the State. It is noteworthy that the genus Cloeodes Traver 1938 and Hermanella Needham and Murphy (Lloyd Entomol Ser 24:1–79, 1924), still do not have records from the State and it is also worth mentioning that all new records represent an important geographic extension. [ABSTRACT FROM AUTHOR]

Baetiella muchei (Braasch, 1978) is recorded for the first time from the Neeru stream of Jammu and Kashmir, India. The variability in larval characters such as size, the shape of the labrum, and the number of the sub-marginal arc of setae in the labrum differs from 12 to 22, degree of fusion of the mandibular incisors, spines on the distal margin of the tergites, distal margin of the paraproct, and the length of cerci are observed from the Indian population when compared to the type specimens. The species number of Baetiella Uéno, 1931 has now increased to six in India. A distributional map of this species is also provided. [ABSTRACT FROM AUTHOR]

Based on material recently collected in northern Thailand, the present study provides an updated of the genus Baetiella, including Gratia. It comprises six species in Thailand, three of them being new species: Baetiella (Gratia) narumonae, Baetiella (Gratia) sororculaenadinae, Baetiella (Baetiella) bispinosa, Baetiella (Baetiella) baei sp. nov., Baetiella (Baetiella) lannaensis sp. nov. and Baetiella (Baetiella) bibranchia sp. nov. Baetiella (Baetiella) baei sp. nov. can be distinguished from other species by the reduction of the posteromedian protuberances on abdominal tergites I–III, the asymmetrical coniform terminal segment of labial palp, the distal margin of abdominal sternites VII–X each with a row of long, spatulate setae, the dorsal margin of femur with two long, robust setae distally. Baetiella (Baetiella) lannaensis sp. nov. is diagnosed by the posteromedian protuberances present on tergites I–VIII, dorsal margin of femur with a regular row of long, rounded, ciliated setae and body surface covered with numerous, dense, rounded scale-like setae. Baetiella (Baetiella) bibranchia sp. nov. can be separated from other species by coxal gills present at the base of forelegs and midlegs. The molecular study based on the mitochondrial gene COI and a larval key to species of Thai Baetiella are also provided. [ABSTRACT FROM AUTHOR]

Based on a well-preserved male imago, a new genus and species Oculephemera mazhenxingi n. gen. et n. sp. of Ephemeroptera are presented in this study. For its distinct characters on head, wings, legs and genitalia, especially the autapomorphies of fused turban eyes and three distal segments of forceps, we erect a new family Oculephemeridae n. fam. herein as the sixth ephemeropteran family discovered from Kachin amber. All the distinguishable characters of the new taxa are illustrated and described; detailed comparisons between related families are also given. The new taxa not only represent a unique clade of mayflies but also give us a chance to modify somehypothesess of the origin, evolution and dispersal of several related lineages. [ABSTRACT FROM AUTHOR]

In larvae of burrowing mayflies (Ephemeroidea), mandibular tusks are generally associated with burrowing and/or feeding. This study reports, for the first time, the use of mandibular tusks as weapons in the aggressive behavior of the burrowing mayfly Rhoenanthus coreanus (Yoon and Bae, 1985) (Potamanthidae). The larvae used their tusks as weapons in combat behaviors such as tusking, which was observed in 60.81% and 62.98% of the studied males and females, respectively. Most cases involved combat by tusking between females (70.45%), followed by combat between males (21.60%), and combat between male and female individuals (3.97%). Aggressive behavior was more common in female larvae with longer mandibular tusks. Positive relationships were observed between the number of cases of aggressive behavior (i.e., tusking) and the size of mandibular tusks in both male and female larvae (p < 0.001). Female larvae with large mandibular tusks (5.00 ± 0.50 mm) could use their tusks to lift their opponents in a manner similar to horned beetles. Contests typically occurred as a result of territorial conflict and served as a means to find or retain occupied shelters for feeding and hiding. [ABSTRACT FROM AUTHOR]

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 jelligen. et sp. nov. and Koonwarrabaetisca duncanisp. nov. For both Cretaceous genera Protobaetisca Staniczek, 2007 and Koonwarrabaetiscagen. 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 Koonwarrabaetiscagen. 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, Koonwarrabaetiscagen. nov. could be the allochthonous component in mayfly fauna of the Koonwarra paleolake. [ABSTRACT FROM AUTHOR]

Little is known about the ecology of early instars of most aquatic insects, particularly their associations with microhabitat (<1 m2) features, such as sediment size distributions, other abiotic parameters, and the overall invertebrate community. This study sought to explore correlations between various biotic and abiotic parameters of a southern Colorado stream and the presence of early instars of Epeorus longimanus (Eaton) (Ephemeroptera: Heptageniidae). A total of 18 samples collected in 2007 and 2013 using a Hess sampler in riffle habitats were used to correlate the size of individuals with biological and abiotic characteristics of the stream, including sediment size, periphyton biomass, entrained organic matter, and the remainder of the benthic invertebrate community, all of which were measured using material from within the sampler. Results from both years showed that early instars of E. longimanus were more likely to be found in areas with smaller sediment sizes, higher live periphyton biomass (but lower overall organic matter), and lower densities of invertebrate predators. [ABSTRACT FROM AUTHOR]

The imaginal stages and eggs of the species Labiobaetis ancoralis Shi and Tong (2014) are first described and photographed based on reared materials from mature nymphs. In addition, its COI gene is sequenced and compared to other species in the same genus. Besides its nymphal labrum with submarginal spatulate-like bristles, abdomen with anchor-shaped markings, its imaginal diagnostic characteristics include slim hindwings with an indistinct costal process, and a cone-like projection between two base-widened forceps. The COI gene sequence of this species is close to L. atrebatinus. The morphological details provided in this research show that the males of the species L. ancoralis, like typical baetids, have reduced hindwings and penes, which have very limited value in classification, but their shapes of forceps can be used in future studies to identify the potentially diverse Chinese Labiobaetis species. [ABSTRACT FROM AUTHOR]

Morocco′s aquatic biodiversity remains insufficiently studied, especially in terms of invertebrates, with numerous gaps persisting, even in protected areas. This study combines our research with existing studies to provide a comprehensive list that encompasses both old and new faunistic and distributional records of three orders of aquatic insects (Ephemeroptera, Plecoptera and Trichoptera) in Tazekka National Park, located in the Eastern Middle Atlas Mountains. We provide an annotated list of 33 species, 23 of which were identified from 1400 specimens collected seasonally between the summer of 2018 and 2019 at 19 sampling sites. The remaining 10 species were identified from the literature sources and were not captured during this study. These 33 species belong to 31 genera and 21 families, comprising 9 species of Ephemeroptera, 14 species of Plecoptera, and 10 species of Trichoptera. The most interesting faunistic novelties consist of the capture of Epeorus cf. torrentium Eaton, 1881 (Ephemeroptera), Micrasema moestum Hagen, 1868 (Trichoptera), and Brachyptera auberti Consiglo, 1957, and Leuctra geniculata (Stephens, 1836) (Plecoptera), which are new records for the Middle Atlas. Furthermore, this work provided the first data on the Ephemeroptera of the Tazekka National Park. Additionally, 9 species of Plecoptera and Trichoptera were newly captured in this park. A chorological analysis revealed that most species are predominantly Mediterranean 61%, while those with a wider distribution occur in the Palearctic constitute the remaining 39%. In terms of endemism, 80% of the species recorded are endemic in the broad sense, with 44% classified as Ibero-Maghrebian, 31% endemic to the Maghreb, and 25% strictly Moroccan endemics. [ABSTRACT FROM AUTHOR]

A new species belonging to the genus Habrophlebia Eaton, 1881 is described at the nymphal stage from the Rif Mountains of Morocco. This species presents unique features, such as the chorionic arrangement of the egg and the ornamentation of the posterior margin of abdominal tergites. It is compared to all west European Habrophlebia species and a table with discriminating characters is given. A phylogenetic reconstruction based on COI sequences fully supports the hypothesis of a new species in the Rif Mountains, with possible further distribution in southern Spain. [ABSTRACT FROM AUTHOR]

The Leptophlebiidae family of mayflies is diverse, with over 640 species and 140 genera worldwide. One of its subfamilies, Terpidinae, is restricted to the Neotropical region and consists of three genera, including Fittkaulus, which have four South American species. This paper redescribes the male imago and proposes a new synonym based on the rearing of nymphs identified as F. cururuensis collected in streams in the Caatinga and Amazon Forest regions of northern and northeastern Brazil. The male imago can be differentiate by having the following combination of characteristics: upper portions of eyes on short stalk; forewing with reddish brown maculae in costal, subcostal and radial sectors; abdomen whitish, with black stripes on posterior margin and dark brown maculae on lateral margins on terga I–VII; penis with proximal half fused; distal half divided, tubular and apically pointed, with latero-dorsal lobes. [ABSTRACT FROM AUTHOR]

To determine the Ephemeroptera (Insecta) fauna in the Pülümür and Ovacık districts of Tunceli province, a total of 2142 nymph samples were collected from 11 stations between March 2019 and July 2020. As a result, 22 taxa belonging to 10 genera of 5 families were identified. The Baetis (Baetis) vernus, B. (B.) lutheri, B. (B.) pavidus, B. (B.) melanonxy, B. (Rhodobaetis) milani, B. (R.) vadimi, Alainites muticus, Epeorus (Ironopsis) alpicola, E. (Caucasiron) znojkoi, Heptagenia (Dacnogenia) coerulans, Rhithrogena germanica, R. semicolorata, R. zelinkai, Ecdyonurus (Helvetoraeticus) picteti, Habroleptoides confusa, and Caenis macrura species were identified at the end of the study which are new records for the research area. [ABSTRACT FROM AUTHOR]

Understanding potential limiting factors affecting population growth of the endangered pallid sturgeon, Scaphirhynchus albus, is important in the upper (UMOR) and lower Missouri River (LMOR) basins. The UMOR is upstream of several reservoirs and generally has more natural habitat features, whereas the LMOR is downstream of these reservoirs and has been channelized to support navigation. In both sections, pallid sturgeon recruitment to age-1 is a concern, but hypothesized for different reasons. One hypothesis in the LMOR centers on food limitation for age-0 fish, which is not considered an issue in the UMOR, but evaluating this hypothesis is challenging given the rarity of age-0 pallid sturgeon. As a result, the related, more abundant shovelnose sturgeon (S. platorhynchus) has been considered as a potential surrogate to assess food-related hypotheses. Thus, the purpose of our study was to compare diets of age-0 sturgeon captured in 2016 from three reaches in the LMOR (Copeland, Langdon, and Lexington) with individuals captured from a reach in the UMOR (Williston) during the same year to provide additional context regarding potential food limitation in the LMOR. Consumption percentage (prey weight in the gut as a percentage of body weight) was similar among all reaches, but diet composition was different for the most downstream reach in the LMOR. Age-0 sturgeon in the UMOR reach as well as the two upstream LMOR reaches primarily consumed Diptera larvae along with Ephemeroptera nymphs. In contrast, age-0 sturgeon in the most downstream LMOR reach (Lexington) almost exclusively consumed Diptera larvae. These results may provide information on relative differences in prey availability between Lexington and the other upstream reaches but the similarity in consumption percentage values across all reaches provide further evidence that age-0 sturgeon are not food limited in the LMOR. Habitat alteration is a factor affecting fishes, including Scaphirhynchus sturgeon, in the Missouri River. The upper portion of this system is fragmented by several dams, yet contains relatively natural riverine habitat features between the reservoirs; the lower portion is heavily altered for barge navigation and bank stabilization. Feeding by age-0 sturgeon in the upper portion has generally been considered adequate for survival, whereas lack of prey has been suggested as limiting survival in the lower portion. We studied age-0 sturgeon prey use in the upper and lower portions of the Missouri River during 2016 and found minimal differences. [ABSTRACT FROM AUTHOR]

We found significantly different percentages of malformed nymphs in two contiguous populations of Serratella ignita (Poda, 1761) in a stream in the northwestern Italy. We suggest that this may be due to a marked difference in the environmental conditions and especially to the effect of pollution on the functional structure of the insect community. [ABSTRACT FROM AUTHOR]

Caenis limai sp. n. is described from the Veerapandi River in Theni, South India based on the larva, adult, and egg stages. The total number of Caenis species in India thereby is being augmented to eleven. The most closely related species to Caenis limai sp. n. is Caenis ulmeriana Malzacher, 2015 and the comparisons between both species are discussed herewith. The most important male subimaginal characters of Caenis americani Srinivasan et al., 2021 is described for the first time. [ABSTRACT FROM AUTHOR]

In temperate and tropical rivers, macroinvertebrates are commonly utilised for biological monitoring. Therefore, it is important to understand their functional feeding guilds and assemblage structure. However, there have been few studies in high‐altitude rivers in East Africa aimed at assessing macroinvertebrate functional guilds. In this study, we examined the macroinvertebrate assemblage characteristics using abundance/diversity metrics and the functional feeding groups (FFGs). We collected physicochemical data and macroinvertebrate samples at seven sites along the Gura River and three sites on the Sagana River. Dissolved oxygen concentration, water temperature, electrical conductivity, pH, turbidity, ammonia, and soluble reactive phosphorus showed significant differences among the sites (p < 0.05). A total of 32 families belonging to 11 orders of macroinvertebrates were collected during the study period. Overall, scrapers were the most abundant FFG, dominated by Heptageniidae (Afronurus). Collector filters and collector gatherers were the second most abundant, while shredders and predators exhibited the least relative abundance. Across all the dominant orders, macroinvertebrate abundance decreased from upstream to downstream sites, with upstream sites exhibiting high diversity and abundance of Ephemeroptera, Diptera, Coleoptera, and Trichoptera taxa. Furthermore, the FFGs in this study differed widely from the River Continuum Concept predictions. Our findings provide crucial understanding of macroinvertebrate assemblage characteristics in high‐altitude rivers. Thus, this study provides additional evidence on the high abundance and diversity of Ephemeroptera and Trichoptera taxa in tropical rivers. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Simple Summary: The riverine ecosystem of the Aurès Mountains in Algeria is situated in the southern part of the Mediterranean basin. This unique region is an important centre of speciation, with a distinct number of regional endemics—some of which are still undescribed or very poorly studied. Given the importance of biomonitoring the ecological status of surface waters in this region, as well as the need to study and protect the diversity of aquatic fauna, information on the taxonomic composition and status of regional species is essential. Our attention was focused on the mayflies of the genus Baetis Leach, 1815 (Ephemeroptera: Baetidae), a typical element of the river macrozoobenthos within the Aurès Mountains. A new species of Baetis (Baetis) dihyae sp. nov. is described for larvae and attributed to the Baetis alpinus species group using morphological and molecular evidence. The affinities of Baetis (Baetis) dihyae sp. nov. to the closely related Palearctic species Baetis (B.) alpinus (Pictet, 1843); the western Alps endemic Baetis (B.) nubecularis Eaton, 1898; and B. (B.) pasquetorum Righetti & Thomas, 2002 (reported only from a few localities in southern France) are discussed in detail. The record and further description of a new species is the first contribution to the knowledge of the relatively diverse mayfly family Baetidae, distributed in the Aurès Mountains. Establishing a representative level of diversity of the macroinvertebrate fauna of the region is closely linked to both field studies and analyses of the main pathways of invasion of its individual elements. Using an extensive data set on the geology and historical biogeography of different faunal groups as well as analysing the diversity of the Baetis alpinus species-group representatives in Western Europe and the Maghreb, we examined in this contribution its colonisation pathways in North Africa. 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. [ABSTRACT FROM AUTHOR]

Despite the essential role of mayflies (Ephemeroptera) in freshwater ecosystems and their long-term use in research and routine biomonitoring in the Carpathian and Pannonian ecoregions, their distribution data are fragmentary and outdated. All published and unpublished data on mayflies from Slovakia was gathered and a database of > 15,000 species records from 2206 localities built with the aims (i) to critically revise available data and assess the completeness of the species inventory, (ii) to identify hotspots of species diversity, and (iii) to provide a benchmark for assessment of species rarity and conservation status in the region. After the critical revision of the data covering more than 100 years, the occurrence of 109 mayfly species in Slovakia was confirmed. The species inventory appears to be nearly complete, as evidenced by the rarefaction curve and a nonparametric species richness estimator. The highest mayfly gamma diversity was recorded below 500 m a.s.l. and in streams of the fifth order, which can be considered hotspots of mayfly diversity in the region. Six species were last recorded before 1990 and thus can be considered extinct in Slovakia. Twenty-nine species could be classified as very rare, with their occurrence frequency decreasing with increasing altitude and most of them being restricted to large lowland rivers and stagnant water habitats in their floodplains. In conclusion, our study provides comprehensive data on key freshwater bioindicators and suggests increasing conservation priorities, especially in lowland river floodplains occupied by several very rare mayfly species. [ABSTRACT FROM AUTHOR]

Riparian avian insectivores not only depend on terrestrial insect prey but also benefit from the inclusion of aquatic prey during critical life-history periods. Diets identified herein show that Prothonotary Warbler (Protonotaria citrea) nestlings were provisioned with aquatic prey throughout the breeding season across their range, but with variation in prey frequency of occurrence and taxonomy. Anthropogenic activity and climate change may impact the trophic link especially between aquatic and riparian habitats by altering the presence, abundance, and timing of prey availability. Thus, we used DNA metabarcoding of fecal samples to quantify the frequency of occurrence of nestling diet items at 9 sites across their breeding range that differed in expected aquatic prey consumption. We analyzed spatial and temporal differences in the occurrence and multivariate diet assemblages of each prey source. Lepidoptera was the predominant terrestrial prey occurring in diets across space and time, whereas emergent aquatic insects and freshwater mollusks in aquatic diet exhibited greater variation. The frequency of emergent aquatic prey occurrence in nestling diets ranged from 61% to 100% across sites and was greater for early-season nestlings. The seasonal decrease in aquatic prey consumption indicates a potential temporal shift in the nutritional landscape from aquatic to terrestrial prey sources and a possible nutritional phenological mismatch for early nestlings as climate change advances the timing of insect emergence. Our findings also suggest that Prothonotary Warblers respond to environmental variability by consuming alternative prey and argue for future research investigating the extent to which shifting diets have nutritional consequences for riparian nestlings. [ABSTRACT FROM AUTHOR]

Macroinvertebrate assemblage assessments act as useful analysis tools for assessing aquatic ecosystems health. These animals also serve as a base trophic level, acting as a source of food for many other aquatic organisms including fish and salamanders. Obtaining baseline data for monitoring aquatic insects and subsequent river health is vital to understand food chains and river ecological interactions. We sampled macroinvertebrate communities in two streams in the Oconaluftee River basin, in the Cherokee Qualla, North Carolina. Over 600 macroinvertebrates were collected and identified to the lowest taxonomic level possible, providing a macroinvertebrate profile of both riffle and run habitats. We identified over 35 genera and report on functional feeding groups, with biotic indices of water quality. Ephemeroptera, Plecoptera, and Trichoptera values varied, 21% and 65.43% for Raven's Fork and 22% and 79.06% for the Oconaluftee rivers. This macroinvertebrate community suggests healthy stream aquatic insects and above average water quality, in spite of the urban land use found in the riparian zones of the sample sites. This research can be used as a baseline for future monitoring of aquatic streams in the area of the Cherokee Qualla. [ABSTRACT FROM AUTHOR]

Biotic interactions involved in colonization are likely important if tolerant aquatic taxa, which have settled first, prevent desired taxa from colonizing when conditions improve. These interactions could be particularly influential during restoration but are poorly understood in streams. We investigated the interactions between 3 stream macroinvertebrate taxa, the snail Potamopyrgus antipodarum (Gray, 1843), mayfly nymphs in the genus Deleatidium , and caddisfly larvae in the family Conoesucidae, to assess whether order of arrival and competitor identity influence colonization success. In a replicated (n = 5) mesocosm experiment, we added an early colonist—either snails, mayflies, or caddisflies—then added 1 of the other 2 invertebrates and measured colonization success. Snails were competitively dominant over mayflies, reducing their colonization regardless of arrival order. Caddisflies, in comparison, had an inhibitory priority effect on both mayflies and snails, whereas mayflies had an inhibitory priority effect on caddisfly colonization. Last, snails had a facilitative priority effect on caddisfly colonization. These results indicate that competitive dominance and multiple types of priority effects could shape freshwater macroinvertebrate assemblages and, therefore, could inhibit desired taxa from colonizing during restoration efforts. Thus, stream restoration strategies should consider the effects of biotic interactions, including priority effects, on restoration outcomes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]