Global arthropod beta-diversity is spatially and temporally structured by latitude.

Global biodiversity gradients are generally expected to reflect greater species replacement closer to the equator. However, empirical validation of global biodiversity gradients largely relies on vertebrates, plants, and other less diverse taxa. Here we assess the temporal and spatial dynamics of global arthropod biodiversity dynamics using a beta-diversity framework. Sampling includes 129 sampling sites whereby malaise traps are deployed to monitor temporal changes in arthropod communities. Overall, we encountered more than 150,000 unique barcode index numbers (BINs) (i.e. species proxies). We assess between site differences in community diversity using beta-diversity and the partitioned components of species replacement and richness difference. Global total beta-diversity (dissimilarity) increases with decreasing latitude, greater spatial distance and greater temporal distance. Species replacement and richness difference patterns vary across biogeographic regions. Our findings support long-standing, general expectations of global biodiversity patterns. However, we also show that the underlying processes driving patterns may be regionally linked.

A DNA barcode library of Austrian geometridae (Lepidoptera) reveals high potential for DNA-based species identification.

Situated in the Eastern section of the European Alps, Austria encompasses a great diversity of different habitat types, ranging from alpine to lowland Pannonian ecosystems, and a correspondingly high level of species diversity, some of which has been addressed in various DNA barcoding projects. Here, we report a DNA barcode library of all the 476 species of Geometridae (Lepidoptera) that have been recorded in Austria. As far as possible, species were sampled from different Austrian regions in order to capture intraspecific genetic variation. In total, 2500 DNA barcode sequences, representing 438 species, were generated in this study. For complete coverage of Austrian geometrid species in the subsequent analyses, the dataset was supplemented with DNA barcodes from specimens of non-Austrian origin. Species delimitations by ASAP, BIN and bPTP methods yielded 465, 510 and 948 molecular operational taxonomic units, respectively. Congruency of BIN and ASAP partitions with morphospecies assignments was reasonably high (85% of morphospecies in unique partitions), whereas bPTP appeared to overestimate the number of taxonomic units. The study furthermore identified taxonomically relevant cases of morphospecies splitting and sharing in the molecular partitions. We conclude that DNA barcoding and sequence analysis revealed a high potential for accurate DNA-based identification of the Austrian Geometridae species. Additionally, the study provides an updated checklist of the geometrid moths of Austria.

Surprising discovery of an enigmatic geometrid in Croatia: Mirlatiaarcuata, gen. nov., sp. nov. (Lepidoptera, Geometridae).

A new monotypic genus of Geometridae, Mirlatiagen. nov., and a new species, M.arcuatasp. nov., are described from Croatia. Based on external and genitalia characters, the new genus is tentatively placed in the subfamily Larentiinae. However, the new genus takes a highly isolated position by having unique characters of the tympanum and showing an unusually long pectination of female antennae. Genetic analysis of a fragmented DNA barcode (mtDNA; cytochrome c oxidase 1) did not result in a clear assignation to any geometrid subfamily or tribe. Adults, male and female genitalia, and habitat photos of the type locality of the new species are illustrated.

Tribal assignment of the genus Eumera Staudinger, 1892, using multi-gene analysis, with description of a new species from Iran (Lepidoptera: Geometridae: Ennominae).

The geometrid moth genus Eumera Staudinger, 1892 consists of five yellow-orange-pinkish species distributed in the western Palearctic, with uncertain tribal classification within the geometrid subfamily Ennominae. In this study, we explored the phylogenetic position of the genus Eumera. Therefore, a concatenated dataset was analyzed, which includes one mitochondrial and up to ten protein-coding genetic markers per taxa. Moreover, we compared some external and internal morphological traits to other closely related genera. Our phylogenetic inference and comparative morphology suggested that Eumera should be included in the tribe Prosopolophini. In addition, a new species, Eumera rajaeii sp. nov. Wanke & Shirvani is described from southern Iran, and diagnosed by molecular data and morphological features. The distribution of the Iranian species is shown on a map. We illustrate external characters and male genitalia of three closely related Eumera species.

Integrative taxonomic revision of the African taxa of the Racotis Moore, 1887 generic complex (Lepidoptera, Geometridae, Ennominae, Boarmiini).

The Afrotropical taxa of the Racotis s.l. generic complex are revised utilising integrative taxonomical methods. Based on the evaluation of genital morphology and analyses of DNA barcodes, a new genus, Afroracotis gen. n. is established to include the Afrotropical "Racotis" species. The new genus is subdivided into 5 subgenera: Afroracotis subgen. n., Herbuloracotis subgen. n., Rwandaracotis subgen. n., Zebracotis subgen. n. and Sokokeracotis subgen. n.. A new monotypic genus is described to include Boarmia ugandaria Swinhoe, 1904 which was combined earlier with the genus Chorodna and recently with Racotis: Chorocotis gen. n.. Two species formerly assigned to Cleora are moved to Afroracotis: A. albitrigonis (Prout, 1927) comb. n., A. atriclava (Prout, 1926) comb. n.. Two species are transferred from Racotis to Colocleora: C. breijeri (Prout, 1922) comb. n., C. incauta (Prout, 1916) comb. n.. Seventeen new Afroracotis species (A. aliena, A. stadiei, A. violetteae, A. fiebigi, A. turlini, A. dargei, A. longicornuta, A. aristophanousi, A. muscivirens, A. chaineyi, A. lydiae, A. smithi, A. ochsei, A. milesi, A. helicalis, A. takanoi and A. staudei spp. n.) and 5 new subspecies (A. squalida thomensis, A. argillacea morettoi, A. longicornuta congolana, A. longicornuta ugandana and A. lydiae orientalis sspp. n.) are described, totalling 27 species and 8 subspecies contained in the genus Afroracotis. Adults and genitalia of all taxa are illustrated in 210 colour and 129 black and white figures demonstrating the intraspecific variability. The distribution of all taxa is illustrated in 6 dot maps. The results of the genetic analyses are figured in four phylograms.

Integrative taxonomic revision of the genus Phaselia Guene, [1858] (Geometridae: Ennominae) in the Middle East and Central Asia.

In the past, the high intraspecific variation of wing pattern within the genus Phaselia Guene, [1858] repeatedly led to misidentifications. In this study, we applied an integrative approach using external and internal morphological characters, along with DNA barcoding and distribution data to review the taxonomy of the genus Phaselia in the Middle East and Central Asia. For this study, 710 specimens, including type specimens and 242 genitalia slides were prepared and examined. As a result, P. phaeoleucaria (Lederer, 1855) stat. rev. is reinstated from synonymy of P. serrularia; P. phaeoleucaria shurensis Wehrli 1941 comb. nov. is regarded as a subspecies of P. phaeoleucaria stat. rev. instead of a subspecies of P. serrularia; P. serrularia catharia Wehrli, 1941 syn. nov. is regarded as a junior synonym of P. phaeoleucaria shurensis comb. nov.; P. narynaria Oberthr, 1913 syn. nov. is regarded as a junior synonym of P. serrularia (Eversmann, 1847); P. pithana Wehrli, 1941 bona sp. is raised to species level from subspecies of P. serrularia. Furthermore, two species and two subspecies are described as new to science: P. smettboi sp. nov., P. sihvoneni sp. nov., P. erika jonubi ssp. nov. and P. erika sindhi ssp. nov. Wing pattern, and both male and female genitalia of all discussed taxa are illustrated, their distribution patterns are shown on a map and CO1 data is evaluated to confirm our taxonomic decisions.

Systematics and integrative taxonomic revision of the tribe Scopulini Duponchel, 1845 in Iran (Lepidoptera: Geometridae: Sterrhinae).

The Iranian taxa of the tribe Scopulini are taxonomically revised. The systematic positions of the genera Cinglis Guene, 1858, Glossotrophia Prout, 1913, Pseudocinglis Hausmann, 1994 and Scopuloides Hausmann, 1994, with uncertain validity and/or position within the tribe Scopulini Duponchel, 1845 (Lepidoptera: Sterrhinae), are further elucidated by use of one mitochondrial and up to nine protein-coding nuclear gene regions. Available type specimens of the described species and more than 2,600 additional specimens were morphologically investigated. In addition, over 400 genitalia preparations were made and examined together with distribution data and DNA barcodes. As a result of the multi-gene analysis, the genera Cinglis stat. rev. and Scopuloides stat. rev. are re-validated at the genus level. The genus Pseudocinglis syn. nov. is regarded as a junior synonym of the genus Cinglis stat. rev. and Glossotrophia syn. nov. is regarded as a junior synonym of the genus Scopula. Cinglis eurata (Prout, 1913) comb. nov. and Cinglis benigna (Brandt, 1941) comb. nov. are combined with the genus Cinglis. Additionally, Cinglis benigna amseli (Wiltshire, 1967) syn. nov. is regarded as a synonym of C. benigna. Scopula adulteraria (Erschov, 1874) stat. nov. is raised from subspecies to species rank; Scopula iranaria Bytinski-Salz & Brandt, 1937 syn. nov. is synonymized with S. flaccidaria (Zeller, 1852); S. transcaspica taftanica Brandt, 1941 syn. nov. is synonymized with S. transcaspica Prout, 1935; S. diffinaria asiatica (Brandt, 1938) syn. nov. is synonymized with S. diffinaria (Prout, 1913) and Glossotrophia bullata Vojnits, 1986 syn. nov. is synonymized with Scopula sacraria ariana (Ebert, 1965). The female genitalia of Scopula lactarioides Brandt, 1941 are described and illustrated for the first time. In total, the presence of 33 species of Scopulini in Iran is confirmed. Wing patterns, male and female genitalia and diagnostic characters of most Iranian Scopulini species are depicted and their distribution ranges are mapped.

Fluctuating insect diversity, abundance and biomass across agricultural landscapes.

Habitat destruction and deterioration of habitat quality caused a severe decline of biodiversity, such as insect diversity. In this study, we analyze insect diversity and biomass across agro-environments. We collected flying insects with 20 malaise traps across a landscape mosaic consisting of organic (eight traps) and conventional (four traps) farmland, as well as across agricultural land that has been recently converted from conventional to organic farming (eight traps). Sampling was conducted over 2 years, in 2019 and 2020, with in total 340 sampling events. We measured the dry weight of the captured organisms and identified species diversity by analyzing Operational Taxonomic Units (OTUs) and Barcode Index Numbers (BINs) via metabarcoding. The results obtained show temporal dynamics. The number of OTUs were always higher than the number of BINs. OTUs and BINs were moderately to highly correlated, while the number of OTUs and BINs were only moderately positively correlated with dry biomass. OTUs and BINs as well as biomass were highest in the recently transformed farmland if compared with pure organic and conventional farmland sites, which showed no significant differences in respect of insect diversity. OTU and BIN numbers but not the OTU/BIN ratio significantly decreased with increasing distance from the nearest forest fringe. The numbers of OTUs, BINs and the OTU/BIN proportion, as well as OTU and BIN/biomass proportions varied strongly over seasons, irrespective of agricultural practice. Based on our findings, we suggest to combine data on insect species richness and biomass measured over a period of time, to derive a largely complete and meaningful assessment of biodiversity for a specific region.

Taxonomic review of the genus Morabia Hausmann amp; Tujuba, 2020 with descriptions of two new species and introducing five new generic combinations (Lepidoptera, Geometridae, Ennominae).

The paper contains the description of two new species of the genus Morabia Hausmann Tujuba, 2020: M. cryptica sp. n. and M. smithi sp. n. The descriptions are based on both morphological data and DNA barcoding. Based on integrative taxonomic analyses, five new combinations are proposed: Morabia nigripunctata (Warren, 1897), comb. n. described from Nigeria, Morabia hero (Viette, 1971), comb. n., Morabia pluto (Viette, 1971), comb. n. described from Madagascar, Morabia herbuloti (Orhant, 2003), comb. n. described from Runion and Morabia distinctaria (Joannis, 1915), comb. n. described from Mauritius are transferred from the genus Ectropis Hbner, 1825 to Morabia. The female genitalia of M. nigripunctata, M. brunnea Hausmann Tujuba, 2020, M. hero and M. herbuloti are described and illustrated for the first time. Detailed diagnoses and re-descriptions of all taxa newly transferred to Morabia are given, interspecific pairwise distances of DNA barcodes are calculated and a maximum likelihood tree is compiled. The paper is illustrated with 38 colour and 38 black and white diagnostic images and a distribution map.

An unexpected species complex unveiled in southern European populations of Phragmatiphila nexa (Hbner, [1808]) (Lepidoptera, Noctuidae, Noctuinae, Apameini).

DNA barcoding analyses of Phragmatiphila nexa (Hbner, 1808) populations unveiled an unexpected divergence in mtDNA of Italian populations, showing the existence of three allopatric cryptic species. The northernmost BIN is shared with specimens from most other European countries, the southernmost one includes specimens from Basilicata and Calabria regions, and the last BIN includes specimens from Apennines, Sardinia and Corsica. Wing pattern as well as male and female genitalia support the existence of three different species along the Italian peninsula: Phragmatiphila nexa north of the Po River for which we designate a neotype, Phragmatiphila insularis (Turati, 1913), stat. rev. in the Apennines as well as in Sardinia (and Corsica), and Phragmatiphila parenzani sp. n. in the south. The Italian distribution of the genus Phragmatiphila is presented in detail.

Taxonomic review of the genus Rhodostrophia Hbner, 1823 (Geometridae: Sterrhinae) in Iran.

So far, the species of the genus Rhodostrophia Hbner, 1823 (Geometridae), their diagnostic characters and their distribution in Iran have not been investigated in detail. Moreover, some species were misunderstood by earlier authors. To solve these problems, a survey of the Iranian Rhodostrophia species based on over 1700 specimens has been executed. The type series of all species known from Iran were examined. Additionally extensive material from different museums and private collections was morphologically studied and compared with the type material. DNA-barcoding was used as an independent line of information and the results were compared with the morphological data. Examination of the type material revealed that R.cuprinaria (Christoph, 1876) was misinterpreted for a long time. The taxon R.nubifera Brandt, 1941 syn. nov. is a younger synonym of Hugo Christophs R.cuprinaria, which was misidentified by himself in his later publications. An available name for R.cuprinaria in the old, erroneous sense is R.phaenicearia (Hampson, 1907). Three subspecies were recognized for R. terrestraria, including R. terrestraria farsi ssp. nov. Additionally, R. terrestraria furialis Brandt, 1941 syn. nov. is hereregarded as junior synonym ofR. terrestraria(Lederer, 1869); Rhodostrophia nubifera nubifera Brandt, 1941 syn. nov. and R. nubifera klapperichi Wiltshire, 1966 syn. nov. are here regarded as junior synonyms of R. cuprinaria (Christoph, 1876). R. abscisaria chlorotica Wiltshire, 1967 syn. nov. is downgraded to synonymy of R. abscisaria Brandt, 1941 and R. peripheres debilis Wiltshire, 1949 syn. nov. to synonymy of R. peripheres Prout, 1938. Rhodostrophia vahabzadehi sp. nov. is described as a new species. In total, 15 species are regarded as valid for the fauna of Iran. External and internal morphological characters for all examined species are illustrated. Distribution data are shown on maps for of all species. An updated checklist is presented for the Iranian representatives of the genus Rhodostrophia.

A novel approach for reliable qualitative and quantitative prey spectra identification of carnivorous plants combining DNA metabarcoding and macro photography.

Prey spectra (the number and composition of captured arthropods) represent a crucial aspect of carnivorous plant ecology, yet remain poorly studied. Traditional morphology-based approaches for prey identification are time-intensive, require specialists with considerable knowledge of arthropod taxonomy, and are hampered by high numbers of unidentifiable (i.e., heavily digested) prey items. We examined prey spectra of three species of closely-related annual Drosera (Droseraceae, sundews) from tropical northern Australia using a novel DNA metabarcoding approach with in-situ macro photography as a plausibility control and to facilitate prey quantity estimations. This new method facilitated accurate analyses of carnivorous plant prey spectra (even of heavily digested prey lacking characteristic morphological features) at a taxonomic resolution and level of completeness far exceeding morphology-based methods and approaching the 100% mark at arthropod order level. Although the three studied species exhibited significant differences in detected prey spectra, little prey specialisation was observed and habitat or plant population density variations were likely the main drivers of prey spectra dissimilarity.

Peering into the Darkness: DNA Barcoding Reveals Surprisingly High Diversity of Unknown Species of Diptera (Insecta) in Germany.

Determining the size of the German insect fauna requires better knowledge of several megadiverse families of Diptera and Hymenoptera that are taxonomically challenging. This study takes the first step in assessing these "dark taxa" families and provides species estimates for four challenging groups of Diptera (Cecidomyiidae, Chironomidae, Phoridae, and Sciaridae). These estimates are based on more than 48,000 DNA barcodes (COI) from Diptera collected by Malaise traps that were deployed in southern Germany. We assessed the fraction of German species belonging to 11 fly families with well-studied taxonomy in these samples. The resultant ratios were then used to estimate the species richness of the four "dark taxa" families (DT families hereafter). Our results suggest a surprisingly high proportion of undetected biodiversity in a supposedly well-investigated country: at least 1800-2200 species await discovery in Germany in these four families. As this estimate is based on collections from one region of Germany, the species count will likely increase with expanded geographic sampling.

Revision of the Lemonia taraxaci complex, with a description of a new species from Italy and clarification of the status of Lemonia strigata (Lepidoptera: Brahmaeidae: Lemoniinae).

The species Lemonia taraxaci (Denis & Schiffermüller, 1755) is divided into three species based on distribution areas and cytochrome c oxidase subunit 1 (COI) distances above 2%: Central European Lemonia taraxaci (type locality: Austria, Vienna area), Eastern European to South Siberian Lemonia sibirica Wnukowsky, 1934 stat. rev., bona sp. (type locality: Russia, Novosibirsk Oblast, Ozero-Karachi and Russia, Altai Krai, Kornilovo), and Italian Lemonia italiana sp. n. (type locality: Italy, Calabria centr., Sila grd., Casali del Manco, San Nicola Silano (CS)). Authorship of Lemonia strigata Antoshin & Zolotuhin, 2011 is reconsidered. The close relation between the typical L. strigata and taraxaci-like adults from the Balkans is proven genetically. According to this, L. strigata is suggested to be a junior synonym of taraxaci-looking Lemonia taraxaci var. montana Buresch, 1915 (type locality: Bulgaria, Rhodope Mts, Musala), although further DNA investigation is needed to prove this hypothesis.

A new species of Typhonoya Prozorov (Lepidoptera, Lasiocampidae, Lasiocampinae, Gastropachini) from the moist broadleaf forest of the Democratic Republic of the Congo.

The second species of the genus Typhonoya Prozorov 2011T. kravchenkoi Prozorov, Mller Zolotuhin sp. n. from the Democratic Republic of the Congo is described. A previously monotypic genus becomes bitypic. One paratype specimen was collected in the buffer zone of the southern part of the Salonga National Park during a one year-long stationary expedition (June 2017June 2018). Spread imagoes, heads, legs, venations and genitalia of both species are figured and compared. Additional notes on the genus description and previously known species are added.

Congruence between morphology-based species and Barcode Index Numbers (BINs) in Neotropical Eumaeini (Lycaenidae).

BACKGROUND: With about 1,000 species in the Neotropics, the Eumaeini (Theclinae) are one of the most diverse butterfly tribes. Correct morphology-based identifications are challenging in many genera due to relatively little interspecific differences in wing patterns. Geographic infraspecific variation is sometimes more substantial than variation between species. In this paper we present a large DNA barcode dataset of South American Lycaenidae. We analyze how well DNA barcode BINs match morphologically delimited species. METHODS: We compare morphology-based species identifications with the clustering of molecular operational taxonomic units (MOTUs) delimitated by the RESL algorithm in BOLD, which assigns Barcode Index Numbers (BINs). We examine intra- and interspecific divergences for genera represented by at least four morphospecies. We discuss the existence of local barcode gaps in a genus by genus analysis. We also note differences in the percentage of species with barcode gaps in groups of lowland and high mountain genera. RESULTS: We identified 2,213 specimens and obtained 1,839 sequences of 512 species in 90 genera. Overall, the mean intraspecific divergence value of CO1 sequences was 1.20%, while the mean interspecific divergence between nearest congeneric neighbors was 4.89%, demonstrating the presence of a barcode gap. However, the gap seemed to disappear from the entire set when comparing the maximum intraspecific distance (8.40%) with the minimum interspecific distance (0.40%). Clear barcode gaps are present in many genera but absent in others. From the set of specimens that yielded COI fragment lengths of at least 650 bp, 75% of the a priori morphology-based identifications were unambiguously assigned to a single Barcode Index Number (BIN). However, after a taxonomic a posteriori review, the percentage of matched identifications rose to 85%. BIN splitting was observed for 17% of the species and BIN sharing for 9%. We found that genera that contain primarily lowland species show higher percentages of local barcode gaps and congruence between BINs and morphology than genera that contain exclusively high montane species. The divergence values to the nearest neighbors were significantly lower in high Andean species while the intra-specific divergence values were significantly lower in the lowland species. These results raise questions regarding the causes of observed low inter and high intraspecific genetic variation. We discuss incomplete lineage sorting and hybridization as most likely causes of this phenomenon, as the montane species concerned are relatively young and hybridization is probable. The release of our data set represents an essential baseline for a reference library for biological assessment studies of butterflies in mega diverse countries using modern high-throughput technologies an highlights the necessity of taxonomic revisions for various genera combining both molecular and morphological data.

Insect taxonomy can be difficult: a noctuid moth (Agaristinae: Aletopus imperialis) and a geometrid moth (Sterrhinae: Cartaletis dargei) combined into a cryptic species complex in eastern Africa (Lepidoptera).

The systematic position of a large and strikingly coloured reddish-black moth, Cartaletis dargei Herbulot, 2003 (Geometridae: Sterrhinae) from Tanzania, has remained questionable since its description. Here we present molecular and morphological evidence showing that Cartaletis dargei only superficially resembles true Cartaletis Warren, 1894 (the relative name currently considered a junior synonym of Aletis Hübner, 1820), which are unpalatable diurnal moths superficially resembling butterflies, and that it is misplaced in the family Geometridae. We transfer it to Noctuidae: Agaristinae, and combine it with the genus Aletopus Jordan, 1926, from Tanzania, as Aletopus dargei (Herbulot, 2003) (new combination). We revise the genus Aletopus to contain three species, but find that it is a cryptic species complex that needs to be revised with more extensive taxon sampling. Our results demonstrate the difficulties in interpreting and classifying biological diversity. We discuss the problems in species delimitation and the potential drivers of evolution in eastern Africa that led to phenotypic similarity in unrelated lepidopteran lineages.

Description of Idaea josephinae sp. n. from the Iberian Peninsula (Lepidoptera: Geometridae).

Idaea josephinae sp. n. is described from the Iberian Peninsula. Differential characters from its North African sister species Idaea lobaria (Chrétien, 1909) in external appearance and genitalia, and in the 5' barcode fragment of the mitochondrial COI gene (the DNA barcode) are presented.

Revision of the genus Prometopidia Hampson, 1902, with description of the new species P. joshimathensis sp. nov. from West-Himalaya and its subspecies P. j. yazakii ssp. nov. from Nepal (Lepidoptera: Geometridae, Ennominae).

The genus Prometopidia Hampson, 1902 and its type-species P. conisaria Hampson, 1902 are redescribed and newly discovered morphological characters are explained. The female holotype of Prometopidia arenosa Wiltshire, 1961, was studied and the species redescribed, its correct position in Prometopidia is verified. The new species P. joshimathensis sp. nov. is described from Joshimath area in India, Uttarakhand province. Sympatric with P. conisaria at Joshimath, P. joshimathensis also occurs at Shimla, Punjab province, and in central and eastern Nepal. Morphological and genetic differences found in the specimens of Nepal are considered subspecific, justifying the new taxon P. joshimathensis yazakii ssp. nov. Types and specimens of Prometopidia across its whole range of distribution from Afghanistan to Nepal, habitats, genitalia, remarkable morphological characters and DNA barcoding-results are figured.

Coverage and quality of DNA barcode references for Central and Northern European Odonata.

BACKGROUND: Dragonflies and damselflies (Odonata) are important components in biomonitoring due to their amphibiotic lifecycle and specific habitat requirements. They are charismatic and popular insects, but can be challenging to identify despite large size and often distinct coloration, especially the immature stages. DNA-based assessment tools rely on validated DNA barcode reference libraries evaluated in a supraregional context to minimize taxonomic incongruence and identification mismatches. METHODS: This study reports on findings from the analysis of the most comprehensive DNA barcode dataset for Central European Odonata to date, with 103 out of 145 recorded European species included and publicly deposited in the Barcode of Life Data System (BOLD). The complete dataset includes 697 specimens (548 adults, 108 larvae) from 274 localities in 16 countries with a geographic emphasis on Central Europe. We used BOLD to generate sequence divergence metrics and to examine the taxonomic composition of the DNA barcode clusters within the dataset and in comparison with all data on BOLD. RESULTS: Over 88% of the species included can be readily identified using their DNA barcodes and the reference dataset provided. Considering the complete European dataset, unambiguous identification is hampered in 12 species due to weak mitochondrial differentiation and partial haplotype sharing. However, considering the known species distributions only two groups of five species possibly co-occur, leading to an unambiguous identification of more than 95% of the analysed Odonata via DNA barcoding in real applications. The cases of small interspecific genetic distances and the observed deep intraspecific variation in Cordulia aenea (Linnaeus, 1758) are discussed in detail and the corresponding taxa in the public reference database are highlighted. They should be considered in future applications of DNA barcoding and metabarcoding and represent interesting evolutionary biological questions, which call for in depth analyses of the involved taxa throughout their distribution ranges.