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Pteronarcys californica (Newport 1848) is commonly referred to as the giant salmonfly and is the largest species of stonefly (Insecta: Plecoptera) in the western United States. Historically, it was widespread and abundant in western rivers, but populations have experienced a substantial decline in the past few decades, becoming locally extirpated in numerous rivers in Utah, Colorado, and Montana. Although previous research has explored the ecological variables conducive to the survivability of populations of the giant salmonfly, a lack of genomic resources hampers exploration of how genetic variation is spread across extant populations. To accelerate research on this imperiled species, we present a de novo chromosomal-length genome assembly of P. californica generated from PacBio HiFi sequencing and Hi-C chromosome conformation capture. Our assembly includes 14 predicted pseudo chromosomes and 98.8% of Insecta universal core orthologs. At 2.40 gigabases, the P. californica assembly is the largest of available stonefly assemblies, highlighting at least 9.5-fold variation in assembly size across the order. Repetitive elements (REs) account for much of the genome size increase in P. californica relative to other stonefly species, with the content of Class I retroelements alone exceeding the entire assembly size of all but two other species studied. We also observed preliminary suborder-specific trends in genome size that merit testing with more robust taxon sampling.

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Temperature significantly impacts ectotherm physiology, with thermal tolerance and metabolic traits typically varying with latitude across species ranges. The drivers of this variation remain unclear, however, despite obvious consequences for population persistence and conservation in the face of ongoing global change. This study explored local adaptation and phenotypic plasticity of metabolic rates and thermal limits in the supratidal rockpool beetle Ochthebius lejolisii. Using populations from localities at different ends of the species range that experience contrasting thermal variability, we simultaneously tested two of the major paradigms of spatial physiological ecology: metabolic cold adaptation (MCA) and the climatic variability hypothesis (CVH). Reciprocal acclimation was conducted under spring temperature regimes of both localities, incorporating local diurnal variation. Metabolic rates were measured by closed respirometry, and thermal tolerance limits estimated through thermography. In line with MCA, the higher-latitude population (colder climate) showed higher metabolic rates and temperature coefficients (Q10s) at lower temperatures than the lower-latitude population. As predicted by the CVH, the lower-latitude population (more variable climate) showed higher upper thermal tolerance but only the higher-latitude population was able to acclimate upper thermal limits. This result suggests trade-offs between physiological thermal limits and thermal plasticity in this species. A limited acclimation capacity could make populations on Mediterranean coasts especially vulnerable in the face of projected increases in extreme temperatures under ongoing climate change.

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During an ongoing project aiming to understand the dynamics of Ephemeroptera biodiversity in the Doce River Basin after the disaster, an unusual large number of Apobaetis Day, 1955 were analyzed. The occurrence of Apobaetis is quite relevant, since the combination of factors such as its small body size and its habitat preferences makes their collection difficult and its presence often neglected. For the first time in science, adults of Apobaetis irai De Lima, Massariol, Cruz & Hamada, 2022 and Apobaetis fiuzai Salles & Lugo-Ortiz, 2002 are described and diagnosed. Apobaetis irai can be easily distinguished, among other characteristics by turbinate portion of compound eyes touching each other along midline; abdominal terga II-III and V-VII with well-marked lines on lateral and posterior margins; posterior margin of subgenital plate with projection broadly rounded to slightly truncate. Apobaetis fiuzai are diagnosed by turbinate portion of compound eyes touching each other posteriorly; mesothorax brown, except for broad cream marks on anterior margin of PSp and SLS, SSLi tinged with white, posterior corner of SMS with a red spot; abdominal terga II-VI translucent orangish-brown, terga VII-X brown, terga II-III and VI with conspicuous red medial mark; posterior margin of subgenital plate with subtriangular projection, apex narrowly truncate; forceps base wider at base, inner irregular edges. The new records of A. irai and A. fiuzai extend the distribution of Apobaetis within Minas Gerais and Espírito Santo States, Brazil. Furthermore, it is reported for the first time cases of gynandromorphs for Apobaetis.

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Caddisflies (Trichoptera) are among the most diverse groups of freshwater animals with more than 16 000 described species. They play a fundamental role in freshwater ecology and environmental engineering in streams, rivers and lakes. Because of this, they are frequently used as indicator organisms in biomonitoring programmes. Despite their importance, key questions concerning the evolutionary history of caddisflies, such as the timing and origin of larval case making, remain unanswered owing to the lack of a well-resolved phylogeny. Here, we estimated a phylogenetic tree using a combination of transcriptomes and targeted enrichment data for 207 species, representing 48 of 52 extant families and 174 genera. We calibrated and dated the tree with 33 carefully selected fossils. The first caddisflies originated approximately 295 million years ago in the Permian, and major suborders began to diversify in the Triassic. Furthermore, we show that portable case making evolved in three separate lineages, and shifts in diversification occurred in concert with key evolutionary innovations beyond case making.

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The order Plecoptera constitutes a relatively small group of aquatic insects, encompassing 17 extant families and comprising over 4400 valid species. In Brazil, the number of valid extant species is 207, located in two families: Perlidae (149) and Gripopterygidae (58). Despite extensive research on the southeastern region of Brazil, there is a notable scarcity of comprehensive studies consolidating geographical records and species richness of Plecoptera in the state of Minas Gerais. This study seeks to increase and refine our understanding of Plecoptera within Minas Gerais, focusing on its diversity and distribution. The initial phase involved a thorough review of articles documenting Plecoptera species in the state. Subsequently, biological material from the Museum of Entomology at the Federal University of Viçosa collection was meticulously identified, and its geographical records were incorporated. Utilizing this dataset, we compiled an updated list of Plecoptera species documented in Minas Gerais. Geographical coordinates of collection points were then mapped and graphically represented to elucidate the geographic and altitudinal distribution of these species. A total of 42 Plecoptera species were identified within the state of Minas Gerais, adding many occurrence records and documenting the first record of Gripopteryx pinima for the state. Despite these advancements, knowledge gaps persist, particularly in the mesoregions of Triângulo/Alto Paranaíba, Oeste de Minas, Vale do Mucuri, and Campo das Vertentes. This endeavor serves as an initial foundation to stimulate further collections and investments in undersampled areas, fostering future monitoring and conservation initiatives for aquatic environments.

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Insects with aquatic larval and terrestrial adult life stages are a key component of coupled aquatic-terrestrial ecosystems. Thus, stressors applied to water bodies adversely affecting those larvae have the potential to influence the riparian zone through altered emergence, with differences in prey availability, timing, or nutrition. In this study, the common model organism Chironomus riparius, a species of Chironomidae (Diptera), was used. This selection was further motivated by its wide distribution in European freshwaters and its importance as prey for terrestrial predators. A stressor of high importance in this context is the globally used mosquito control agent Bacillus thuringiensis var. israelensis (Bti) which has been shown to affect Chironomidae. Here, we investigated the ability of chironomid populations to adapt to a regularly applied stressor, leading to a reduced impact of Bti. Therefore, the initial sensitivity of laboratory populations of C. riparius was investigated under the influence of field-relevant Bti treatments (three doses × two application days) and different food sources (high-quality TetraMin vs. low-quality Spirulina). Following a chronic exposure to Bti over six months, the sensitivity of pre-exposed and naïve populations was re-evaluated. Food quality had a strong impact on emergence timing and nutrient content. In addition, alterations in emergence time as well as protein and lipid contents of chronically exposed populations indicated a selection for individuals of advantageous energetics, potentially leading to a more efficient development while combating Bti. Signs of adaptation could be confirmed in five out of 36 tested scenarios suggesting adaptation to Bti at the population level. Adaptive responses of one or several species could theoretically (via eco-evolutionary dynamics) result in a community shift, favouring the prevalence of Bti-tolerant species. (In)direct effects of Bti and the adaptive responses at both population and community levels could affect higher trophic levels and may determine the fate of meta-ecosystems.

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Aquatic ecosystems are among the most affected by anthropogenic impacts, and the rapid detection and measurement of these impacts are of great importance for the maintenance of such environments. The order of aquatic insects Odonata has emerged as an important bioindicator of environmental quality due to its sensitivity to environmental changes and its ecophysiological requirements, which make them closely associated with habitat conditions. The aim of this study was to test whether the Zygoptera/Anisoptera ratio can be used as an effective tool to assess anthropogenic changes in Cerrado streams. Our hypothesis is that the proportion of Zygoptera/Anisoptera is an efficient tool for measuring environmental alterations in Cerrado streams, with a positive relationship between habitat integrity and the proportion of Zygoptera and an inverse relationship with the proportion of Anisoptera. Adults were collected in 44 streams of the Cerrado Biome in the eastern Maranhão state. The Habitat Integrity Index (HII) was used to verify the environmental gradient. Our hypothesis was corroborated, with a positive relationship between the richness and abundance of Zygoptera and HII, while an inverse relationship was observed for Anisoptera. According to our results, streams exhibiting a Zygoptera abundance of 68% or higher and richness of 58% or higher can be classified as preserved, while those showing an Anisoptera abundance and richness surpassing 31% and 41%, respectively, may be deemed altered. The patterns detected in the Cerrado were similar to those found in studies of the Amazon Biome and the Atlantic Forest, confirming the effectiveness of this method even for naturally open environments, such as the Cerrado. We conclude, therefore, that this method can be used as a tool to generate rapid results in monitoring studies, with low cost and easy application, enabling the development of mitigation, control, and conservation measures for extremely threatened environments such as those found in the Cerrado Biome.

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Understanding diversity patterns and underlying drivers is one of the central topics in the fields of biogeography and community ecology. Aquatic macroinvertebrates are widely distributed in various wetlands and play vital ecological roles. Previous studies mainly have focused on macroinvertebrate diversity in a single type of wetland. Our understanding of the differences in diversity patterns and underlying drivers between different wetland types remains limited. Here, we compared diversity patterns and community assembly of floodplain wetlands (FWs) and non-floodplain wetlands (NWs) in the Sanjiang Plain, Northeast China. We found that the taxonomic richness and abundance were higher in NWs than those in FWs. Nineteen taxa were identified as habitat specialists in the NWs, whereas only four taxa were designated as habitat specialists in the FWs. In addition, the FW and NW assemblages exhibited contrasting compositions. Spatial and environmental variables explained the largest variations in the macroinvertebrate assemblages of NWs and FWs, respectively. Normalised stochasticity ratios and Sloan neutral models confirmed that the macroinvertebrate community assembly of both wetland types was driven largely by stochastic processes. Stochastic processes were more prominent in shaping macroinvertebrate communities of FWs, whereas a stronger dispersal limitation was detected in NWs. Our results revealed contrasting diversity patterns and assembly mechanisms of macroinvertebrate communities in FWs and NWs. We underscore the importance of flood disturbance in shaping wetland ecosystems in the Sanjiang Plain and highlight that conservation and restoration actions cover different types of wetland habitats.

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The aquatic bug family Naucoridae (Hemiptera: Heteroptera: Nepomorpha) is currently represented in Brazil by 68 species. Although the diversity of the family has been the target of several recent studies, large areas of the country are still unexplored and several species that have been deposited in entomological collections are waiting for a formal description. Aiming to fill these knowledge gaps, a series of expeditions were carried out in six states of eastern Brazil between 2018 and 2023: Alagoas, Bahia, Ceará, Espírito Santo, Pernambuco, and Sergipe. The fieldwork targeted protected areas, but surrounding regions were also explored. The material obtained, in addition to specimens previously deposited in a national entomological collection, revealed the existence of Australambrysus margaritifer Jordão, Santos and Moreira, a new species herein described, and new records for other 11 species and two subspecies belonging to the genera Carvalhoiella De Carlo, 1963, Limnocoris Stål, 1876, Maculambrysus Reynoso-Velasco and Sites 2021, and Pelocoris Stål, 1876.

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AbstractFreshwater salinity regimes vary naturally and are changing in response to anthropogenic activities. Few insect species tolerate saline waters, and biodiversity losses are associated with increasing salinity in freshwater. We used radiotracers (22Na, 35SO4, and 45Ca) to examine ion uptake rates across concentration gradients in mayflies (Ephemeroptera), caddis flies (Trichoptera), and mosquitoes (Diptera) and made observations for some traits in seven other taxa representing mayflies, stone flies (Plecoptera), true flies (Diptera), and true bugs (Hemiptera). We further assessed the permeability of the cuticle to 3H2O influx and 22Na efflux when faced with deionized water in these same taxa. We hypothesized a relationship between uptake rates and reported saline tolerances, but our data did not support this hypothesis, likely because acclimatory responses were not part of this experimental approach. However, we found several common physiological traits across the taxa studied, including (i) ionic uptake rates that were always positively correlated with dissolved concentrations, (ii) generally low Ca uptake rates relative to other freshwater taxa, (iii) greater Na loss than Na uptake in dilute conditions, (iv) ion uptake that was more variable in ion-rich conditions than in dilute conditions, and (v) 3H2O influx that occurs quickly (but this rapidly exchangeable pool of body water accounts for a surprisingly small percentage of the water content of species tested). There remains much to learn about the physiology of these important organisms in the face of changing salinity regimes worldwide.

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Poxyaibamberus Andersen & Dantas, gen. nov. is erected based on the males of two species, P.jamanximensis Andersen & Dantas, sp. nov. from Jamanxim National Park, Pará State, Brazil, and P.ubajarensis Andersen & Dantas, sp. nov. from Ubajara National Park, Ceará State, Brazil. Both species have a comparatively short and wide head, with large eyes and short, five-segmented palps; a strong subapical seta on the ultimate flagellomere; scalpellate acrostichals; no setae on the wing veins except for one seta on the brachiolum; a long costal extension; and a large triangular anal point and a very long heel on the gonostylus. The systematic position of the new genus is briefly discussed.

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Athabasca oil sands in Alberta, Canada, are large bitumen deposits and are one of the world's largest petroleum reserves. This research contributes to the growing body of knowledge on the influence of this naturally occurring bitumen on freshwaters. Using laboratory-based exposure studies, we examined the life cycle responses of the aquatic midge Chironomus riparius to both naturally formed solid bitumen incorporated in the sediment and its corresponding aqueous extracts, denominated as elutriates. The 28-day partial life cycle assay involved bitumen samples from two distinct geological origins in the Athabasca River Basin (Clearwater and McMurray formations), comprising both weathered and freshly collected bitumen from a total of 4 different rivers. Our results demonstrate a measurable impact of sediment-embedded bitumen on C. riparius life history traits, namely on their growth and emergence patterns. Furthermore, we observed that bitumen samples from the Ells River (McMurray formation), which were freshly collected from exposed river bank soil deposits, exerted the strongest effects on most studied eco-physiological endpoints. Bitumen extracts from the Steepbank River and Athabasca River in the McMurray Formation and Steepbank River in the Clearwater Formation followed, underscoring the geographical variance in bitumen-induced toxicity. Exposure to elutriates, simulating "weathered" bitumen generally did not induce adverse effects in C. riparius life-cycle endpoints compared to elutriates prepared from freshly eroded bank soils. This emphasizes the importance of considering bitumen sources, their age, and the aquatic receiving environment when assessing potential adverse exposure effects. Our study shows that exposure to freshly eroded soils/sediments can potentially affect benthic invertebrates. More research is needed to understand how hydrological changes affect bitumen sediment exposure and the associated risks to aquatic biota.

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Aquatic insects are a major indicator used to assess ecological condition in freshwater environments. However, current methods to collect and identify aquatic insects require advanced taxonomic expertise and rely on invasive techniques that lack spatio-temporal replication. Passive acoustic monitoring (PAM) is emerging as a non-invasive complementary sampling method allowing broad spatio-temporal and taxonomic coverage. The application of PAM in freshwater ecosystems has already proved useful, revealing unexpected acoustic diversity produced by fishes, amphibians, submerged aquatic plants, and aquatic insects. However, the identity of species producing sounds remains largely unknown. Among them, aquatic insects appear to be the major contributor to freshwater soundscapes. Here, we estimate the potential number of soniferous aquatic insects worldwide using data from the Global Biodiversity Information Facility. We found that four aquatic insect orders produce sounds totalling over 7000 species. This number is probably underestimated owing to poor knowledge of aquatic insects bioacoustics. We then assess the value of sound producing aquatic insects to evaluate ecological condition and find that they might be useful despite having similar responses in pristine and degraded environments in some cases. Both expert and automated identifications will be necessary to build international reference libraries and to conduct acoustic bioassessment in freshwaters. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

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Experiments are useful scientific tools for testing hypotheses by manipulating variables of interest while controlling for other factors that can bias or confuse the results and their interpretation. To ensures accuracy and reproducibility, experiments must have transparent and repeatable methodologies. Due to the importance of shredder invertebrates in organic matter processing, carbon cycling, and nutrient cycling, we tested experimentally the effect of different methodological approaches in microcosm experiments on the consumption and survival of shredders. We found that the shredder species, the presence or absence of the case, and the use or non-use of air-pumps in the microcosms did not affect shredder performance (i.e., consumption and survival). Furthermore, the type of water (stream or bottled) did not affect shredder performance. On the other hand, the amount of light had a negative effect on shredder performance, with constant light (i.e., 24 h) reducing shredder consumption and survival. Our results demonstrate that the use of different methodologies does not always result in changes in outcomes, thus ensuring comparability. However, luminosity is a critical factor that deserves attention when conducting microcosm experiments. Our findings provide valuable insights that can assist researchers in designing experiments with shredders from neotropical streams and conducting systematic reviews and meta-analyses.

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Background: The Potamophylaxwinneguthi species cluster comprises species with limited distribution, currently documented from Kosovo, Serbia, Bosnia and Herzegovina and Bulgaria. New information: In this paper, we describe a new species, Potamophylaxkosovaensis sp. nov., discovered in two tributaries of the Ibër River Basin, within the Kopaonik Mountains of the Republic of Kosovo. Morphologically, males of this species closely resemble those of P.idliri Ibrahimi, Bilalli & Kucinic, 2022 from Serbia's Jastrebac Mountain and P.humoinsapiens Ibrahimi & Bilalli, 2023 from the Sharr Mountains in the Republic of Kosovo. However, the new species can be distinguished by its smaller aedeagus, thicker and differently-shaped parameres, as well as distinctive patterns and elongated spines on the parameres. Notably, this species is restricted to spring areas, indicating sensitivity to water pollution and habitat degradation. Additionally, we provide a list of caddisfly species found in sympatry with the new species.Potamophylaxkosovaensis sp. nov. is the third known species within the Potamophylaxwinneguthi species cluster, identified in the Republic of Kosovo.

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Factors responsible for species distribution of benthic macroinvertebrates, including responses at different spatial scales, have been previously investigated. The aim of the present research was to review the most relevant factors explaining chironomid species distribution focusing on factors operating at different spatial scales, such as latitude, longitude, altitude, substrate, salinity, water temperature, current velocity, conductivity, acidity, dissolved oxygen, nutrient content etc. acting at regional levels and at a large or small water basin level. Data including chironomid species abundances from different lentic and lotic waters in Italy and other surrounding countries were analyzed using partial canonical correspondence analysis (pCCA) and multiple discriminant analysis (DISCR). Spatial analyses, including univariate Moran's I correlograms, multivariate Mantel correlograms and Moran's eigenvector maps (MEMs), were thereafter carried out. The results showed that habitat type, including different types of lotic waters (i.e., kryal, crenal, rhithral, potamal) and different lake types (i.e., littoral, sublittoral, profundal zones), is the most significant factor separating chironomid assemblages, while spatial factors act only as indirect influencers.

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Many native insects have evolved defenses against native predators. However, their defenses may not protect them from non-native predators due to a limited shared history. The American bullfrog, Aquarana catesbeiana (Anura: Ranidae), which has been intentionally introduced to many countries, is believed to impact native aquatic animals through direct predation. Adults of whirligig beetles (Coleoptera: Gyrinidae), known for swimming and foraging on the water surface of ponds and streams, reportedly possess chemical defenses against aquatic predators, such as fish. Although whirligig beetles potentially encounter both bullfrogs and other frogs in ponds and lakes, the effectiveness of their defenses against frogs has been rarely studied. To assess whether whirligig beetles can defend against native and non-native frogs, we observed the behavioral responses of the native pond frog, Pelophylax nigromaculatus (Anura: Ranidae), and the invasive non-native bullfrog, A. catesbeiana, to native whirligig beetles, Gyrinus japonicus and Dineutus orientalis, in Japan. Adults of whirligig beetles were provided to frogs under laboratory conditions. Forty percent of G. japonicus and D.orientalis were rejected by P. nigromaculatus, while all whirligig beetles were easily consumed by A. catesbeiana. Chemical and other secondary defenses of G. japonicus and D. orientalis were effective for some individuals of P. nigromaculatus but not for any individuals of A. catesbeiana. These results suggest that native whirligig beetles suffer predation by invasive non-native bullfrogs in local ponds and lakes in Japan.

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Cylindrostethus Fieber, 1861 is one of the most striking genera of water striders (Insecta: Hemiptera: Gerridae) and has Pantropical distribution. Members of this group can be recognized by the very long, cylindrical body; the short antennomere IV; the short labium not reaching the mesosternum; and by characteristics of the abdomen of males and females. Although Neotropical representatives of the genus have been revised, there are pending taxonomic issues related to this fauna, and that of the Eastern Hemisphere has been barely studied in recent years. Here, we present a short note about the authorship of Cylindrostethus, an updated key to all species of the genus, a new synonymy, and the description of a previously unknown macropterous male of C. hungerfordi Drake and Harris.

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Discoveries of endemic species highlight areas of biogeographic and conservation interest. Endemic species, however, are often morphologically disguised as more common and widespread species. The larval polytene chromosomes revealed a new species of black fly, Prosimulium fungiforme, from the Djurdjura Mountains of northern Algeria, and its female, male, pupa, and larva are described. The species is chromosomally unique; none of its 11 chromosomal rearrangements are shared with other species. Although the new species structurally resembles Prosimulium rufipes (Meigen) with which it previously has been confused, it can be distinguished from all other known species of Prosimulium in the Western Palearctic based on at least one character in each described life stage. Symbiotic organisms included two species of microsporidia, at least one of which is probably undescribed, one unknown protozoan pathogen novel in simuliids, and the trichomycete fungus Harpella melusinae Léger and Duboscq. Associated simuliid species included at least one new species of the genus Helodon. The new species of Prosimulium is tentatively considered endemic to the mountains of northern Algeria but might be expected in the mountains of eastern Morocco and northern Tunisia and perhaps in Sicily. If its endemic status holds, it would be the only nominal species of black fly unique to Algeria.

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DNA barcoding is an essential tool in modern biodiversity sciences. Despite considerable work to barcode the tree of life, many groups, including insects, remain partially or totally unreferenced, preventing barcoding from reaching its full potential. Aquatic insects, especially the three orders Ephemeroptera, Plecoptera, and Trichoptera (EPT), are key freshwater quality indicators worldwide. Among them, Plecoptera (stoneflies), which are among the most sensitive aquatic insects to habitat modification, play a central role in river monitoring surveys. Here, we present an update of the Plecoptera reference database for (meta)barcoding in Switzerland, now covering all 118 species known from this country. Fresh specimens, mostly from rare or localized species, were collected, and 151 new CO1 barcodes were generated. These were merged with the 422 previously published sequences, resulting in a dataset of 573 barcoded specimens. Our CO1 dataset was delimited in 115 CO1 clusters based on a priori morphological identifications, of which 17% are newly reported for Switzerland, and 4% are newly reported globally. Among the 115 CO1 clusters, 85% showed complete congruence with morphology. Distance-based analysis indicated local barcoding gaps in 97% of the CO1 clusters. This study significantly improves the Swiss reference database for stoneflies, enhancing future species identification accuracy and biodiversity monitoring. Additionally, this work reveals cryptic diversity and incongruence between morphology and barcodes, both presenting valuable opportunities for future integrative taxonomic studies. Voucher specimens, DNA extractions and reference barcodes are available for future developments, including metabarcoding and environmental DNA surveys.

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