DNA barcode reference libraries provide useful tools for specimen identification, highlighting potential new species and detecting introduced ones. Here, we present a comprehensive DNA barcode library for European ants and, in order to tackle the Linnean, Wallacean and Darwinian shortfalls of this group, we provide an updated checklist, distribution data, mitochondrial genetic diversity maps and mitochondrial gene trees. The European ant fauna is here established to include 55 genera and 650 species (587 of which are native), including one species newly recorded for Europe and novel citations for 26 species from 11 countries. Our genetic dataset includes 6530 georeferenced COI sequences (62.1% d e novo) for 506 species (77.8%) across all genera. On average, 12.9 sequences were obtained per species, and 209 species were sequenced for the first time. We generated intra- and interspecific genetic distance estimates, 52 genus-level trees, mitochondrial genetic diversity and specimen maps for 384 species, as well as haplotype networks for 289 species, available in the Atlas V1.0 'The Mitochondrial Genetic Diversity Maps of European Ants'. We estimate that 56.3% of European ants are monophyletic with respect to the COI gene and can be unambiguously identified by DNA barcoding, though performance varies widely among genera. We observed moderate levels of barcode sharing (19.3%) and of barcode gap presence (47.6%), as well as high levels of intraspecific divergences (up to 17.9%). These findings likely reflect both biological and operational factors and highlight the existence of potential cryptic taxa and the need for taxonomic revisions. The framework presented here aims to facilitate future research, species discovery and conservation of European ants.

Evolution relentlessly challenges any concept of species, and human efforts to fit a taxonomic hypothesis to patterns in nature often seem unsatisfactory. Genomics show that a solution does not always come with more data: a fine-scaled view may reveal populations with a more gradual array of differentiation, infer cases of hybrid origin and bring to light the existence of ghost populations. The false heath fritillary, Melitaea diamina, is a Palearctic butterfly with patchy, localized populations highly dependent on humid temperate habitats. Despite its extensive geographic range, populations at the southern edge of its European distribution are scarce and poorly studied genetically. Here, we employed genome-wide data to reveal the existence of two major groups in M. diamina: an Iberian and a Eurasian lineage. Within Iberia, we documented a remarkable diversity: the populations in the Pyrenees are of hybrid origin between the Eurasian lineage and a now apparently extinct Iberian population. The ghost population was related to three extant additional Iberian lineages that align with mitochondrial differentiation, distinct morphological traits, and/or ecological specialization in the form of host plant association. Gene flow analyses suggested historical admixture despite current isolation, underscoring the complex evolutionary history of these populations. We attempt a revised taxonomic framework for this novel array of evolutionary significant units, adopting an updated subspecies concept-defining subspecies as incompletely separated lineages within a more inclusive lineage. Such an approach allows accurate representation of evolutionary complexity without prematurely elevating these populations to species rank, thereby informing targeted, biologically meaningful conservation strategies.

Global changes are leading to widespread species redistribution. Comprehensive assessments of range shift dynamics and their drivers are difficult, partly due to the variation in range shift detection over space and taxa. Here we compile documented range shift records for 1,758 butterfly species from 105 countries and territories, representing ~10% of the known diversity of these insects. Most species (80%) experienced range expansions, and most range shifts (79%) were associated with climate change and extreme weather events. A substantial proportion of species in our dataset contracted their ranges (27%) or shifted along elevational gradients (22%). We report widespread horizontal range expansions and contractions across tropical countries, with less evidence for elevational range shifts. We show that a clearer picture of range shift dynamics emerged only through the combination of different types of data, with expert assessments and non-English studies alleviating potential biases. Our findings of climate-driven range shifts call for concerted efforts to improve inclusive data monitoring and conservation efforts, especially for tropical countries, where human-induced land-use changes exert additional critical pressure.

Conservation biases have been documented since the first emergence of the concept of biodiversity in the 1980s, showing a systematic disproportion in the allocation of research and conservation efforts among taxa. One factor underlying this disproportion, gaining prominence in recent literature, is variation in species’ perceived beauty, shaped by human visual preferences. Here, we integrate a large-scale survey of the perceived beauty of European butterflies involving >21000 respondents from >100 countries within a full interconnected and time-explicit network linking species’ beauty, public attention, research and conservation efforts, and the regulatory framework at the continental EU level (Fig. S1). We found that a beauty bias consistently shapes public attention, research and conservation efforts, interacting with species detectability: research efforts and public attention concentrate on widespread and attractive species, whereas the legal conservation framework, particularly the Convention on the Conservation of European Wildlife and Natural Habitats (hereafter: Bern Convention, BC, 1979) and the EU Habitats Directive (hereafter: HD, 1992), favours those that are both visually appealing and range-restricted. Because these frameworks guide funding and management actions, initial aesthetic preferences influencing BC and HD have produced long-lasting institutional effects that still shape research and conservation actions on European butterflies. By contrast, European IUCN Red Lists do not privilege beautiful species and increasingly identify less conspicuous taxa as threatened. This mismatch reveals a tension between scientific assessments of extinction risk and historically embedded conservation priorities. Our findings suggest that recognizing beauty bias is vital for aligning conservation with actual ecological urgency.

Historical climatic oscillations and geographic barriers have profoundly shaped genetic diversity and speciation across Europe, particularly within glacial refugia. The widespread butterfly Cyaniris semiargus (Mazarine Blue) is a striking example of such divergence, especially in its southernmost populations, which are fragmented across montane and coastal habitats. Using genome-wide ddRADseq data and environmental analyses, we investigated the genetic structure, gene flow and ecological differentiation of C. semiargus across the western Palearctic, with a focus on its isolated southern populations. Our results reveal four deeply diverged genetic lineages within the Iberian Peninsula and one in North Africa. These lineages exhibit strong genetic structure, ecological specialization and minimal gene flow, consistent with allopatric divergence strengthened by local adaptation. Coastal populations show host plant specialization and adaptation to milder and more stable climates, while montane lineages persist in climatically extreme refugia. Interestingly, another lineage in the Peloponnese is following similar high-altitude climatic selective pressures. Together, these findings point to parallel processes of ecological speciation across both montane and coastal environments. Adopting a conservative taxonomic approach, albeit reflecting their evolutionary and conservation significance, we recognize these lineages as subspecies. Our study highlights the role of glacial refugia, habitat specialization and ecological divergence in shaping patterns of biodiversity, and underscores the urgent need for lineage-specific conservation measures.

Pollinators are declining globally, highlighting the urgent need for accurate methods to monitor their densities and abundances. Distance sampling (DS) is a promising, non-invasive method for estimating insect population abundances, but its estimates have not been compared with independent counts of population size to validate DS efficacy for insects. We addressed this methodological gap on Giannutri Island (Italy), where two strongly declining pollinator populations of Anthophora dispar and Bombus terrestris coexist with managed honey bees (Apis mellifera). DS field surveys, targeting both managed and wild bees, were conducted across 41 transects spanning five land cover types over 12 sampling days. We validated this method by verifying that the number of foraging honey bees estimated with DS is consistent with the literature reported proportion of workers outside the hives (similar to 12.5%-20%) of the known reference population of managed colonies. Using DS , we also verified: (1) a strong consistency in abundance estimates across consecutive days; (2) significant effects of weather conditions on detected abundances and temporal trends matching the known phenology of adults in both wild species; (3) marked differences in densities across land cover types consistent with the known link between pollinator abundances and vegetation structures. In conclusion, DS offers a practical method for obtaining reliable estimates of population size for midsized to large insects when individuals can be readily observed and identified. While its applicability to smaller species and closed habitats may thus be limited, it represents a valuable tool where traditional methods are impractical.

Aim Comparison between islands and equivalent mainland areas to dissect the effect of area, isolation and species traits in determining island genetic endemicity and genetic differentiation.Location The Western Mediterranean region.Time Period Current.Major Taxa Studied Butterflies (Lepidoptera, Papilionoidea).Methods We analysed 10,367 COI sequences from 105 species, 34 islands and 47 sea straits, along with four functional species traits. We compared determinants of genetic diversity (nucleotide diversity, NucDiv), endemic mutations (EM) and the Dst fixation index between island populations and similarly sized mainland populations (Continental Area Equivalents, CAEs). Generalised linear mixed models tested fixed effects and interactions of island characteristics and species traits. We also evaluated whether population-level effects (individual species increasing differentiation with island size and isolation) or community-level effects (larger, less isolated islands hosting more genetically divergent species) better explain observed island patterns.Results CAEs and islands exhibited highly distinct genetic signatures. NucDiv was higher in CAEs while Dst was higher across sea straits than between land areas separating CAEs, particularly for larger islands and non-migratory species. EM increased with island area, especially in non-migratory and small species. Island communities were significantly nested. Widespread species also showed lower genetic variation, thus producing a strong community-level effect. The population-level effects showed a weaker effect. Counterintuitively, increasing isolation did not increase divergence, as both processes tended to reduce genetic differentiation in more isolated islands.Main Conclusions Comparing islands with CAEs reveals that even narrow sea barriers of a few kilometres greatly reduce gene flow in non-migratory butterflies, increasing genetic differentiation to a greater extent than similar mainland distances. After controlling for the presence of sea straits, island size predicts genetic divergence while increasing isolation does not. Overall, endemicity remains low, indicating that mainland-driven genetic turnover, rather than in situ evolution, dominates insular genetic patterns.

Papilio alexanor exhibits a disjunct distribution across the western Palearctic. Records of this species from southern Italy have been rare and sporadic, leading to suggestions that these individuals might be strays originating from the Balkans or Greece. In this study, we provide an updated list of observations of P. alexanor in southern Italy, including records of ovipositing females and early larval instars, as well as DNA sequences from the COI barcode of five specimens from Monte Pollino (Calabria) and Cilento (Campania), to investigate the origin of these southern Italian populations. Our findings support the hypothesis that P. alexanor is native to southern Italy, with three unique COI haplotypes differing by a single nucleotide from populations in Greece (Lesbos) and the Balkans. We discuss these results in the context of the species’ biogeography and conservation. The populations of P. alexanor in southern Italy are small, currently not recognized as native, and partially distributed outside of protected areas. We propose a revision of the conservation status of this species in Italy and highlight the need to invest on locating and safeguarding potentially stable populations in southern Italy.

We present a browser-based curation tool (Library Curation Tool) developed to support expert validation of taxonomic records derived from the Barcode of Life Data System (BOLD). This tool forms a critical component of a two-step approach designed within the EU Horizon Europe project Biodiversity Genomics Europe (BGE) to build a high-quality, curated DNA barcode reference library for European species. The upstream component—a bioinformatics pipeline described in a companion publication—automatically filters, cleans, and ranks BOLD records based on metadata completeness, sequence quality, and taxonomic consistency. However, certain complex cases, such as misidentifications, nomenclatorial problems (e.g. synonymy), BIN-sharing (multiple species sharing one BIN) or BIN-splitting (a single species associated with multiple BINs), cannot be fully resolved by automated methods and require expert judgment.Our Library Curation Tool enables taxonomic experts to interactively inspect, validate, or exclude individual records, update species names, assign curation statuses, and provide curator notes. The tool supports real-time statistics for BIN conflicts and dynamically updates curation metrics as the expert interacts with the data. Its user interface is designed to simplify the review of large datasets while ensuring consistency, traceability, and minimal risk of structural errors common in spreadsheet-based curation workflows.The curated output from this tool, combined with the automated pipeline, forms the foundation of a reference library suitable for accurate DNA-based species identification in biodiversity monitoring and ecological studies. By integrating expert knowledge into a standardized and scalable interface, the tool supports distributed community curation of DNA barcode reference data. Although currently implemented as a local application, the workflow is designed to facilitate the consolidation of expert annotations into shared, FAIR-compliant reference libraries and future integration with community infrastructures such as BOLD and BOLD-Europe.

Contact zones, where genetic lineages meet, provide a unique opportunity to study speciation and reveal how reproductive barriers emerge.1,2,3 However, species ranges are dynamic, contact zones may be ephemeral,4,5 and reinforcement-selection against hybrids-is an elusive phenomenon.6,7,8 We use an integrative approach-genomic, chemical, and morphological data coupled with ecological and demographic modeling-to evaluate lineage limits, reconstruct contact history, and infer reproductive isolation strength and mechanisms in the protected Clouded Apollo butterfly (Parnassius mnemosyne) in Europe.9 The status of this taxon is highly debated: a potential cryptic species (Parnassius turatii) edging P. mnemosyne sensu stricto in the Eastern Alps has been proposed, yet evidence remains inconsistent in the absence of genomic data.10,11,12,13,14,15,16,17,18 We reveal two genetic lineages that diverged about 0.8 million years ago and experienced two successive episodes of secondary contact. During the last glaciation, the lineages met in western Europe, which resulted in admixture and the formation of hybrid Pyrenean populations before reproductive isolation had evolved. In contrast, genomic data show no detectable gene flow at their present-day contact zone in the Eastern Alps, despite morphological and ecological similarity. Evidence of mutual chemical character displacement in males at this contact suggests bidirectional reinforcement in action. These findings portray a system in which lineages that once exchanged genes now re-encounter each other and reproductive isolation is generated-a second chance for speciation to succeed-and demonstrate that the Clouded Apollo comprises two cryptic species, with implications for EU legislation implementation and IUCN assessments.9,19,20.

We report the butterfly species of four national parks in the central Apennines (Abruzzo, Lazio e Molise; Gran Sasso e Monti della Laga; Maiella; Monti Sibillini). Since most literature records are outdated, we update them with new data collected during targeted surveys conducted as part of the activities required by a ministerial directive, also adding citizen science records and data from other sampling activities. Overall, we report 157 species, with several new records for the parks. Many orophilous species have their only Apennine populations in the study area and many species of conservation interest occur here.

Biogeographic barriers are typically considered prominent geographic features that block or severely restrict dispersal and gene flow. However, mating barriers can also emerge within continuous suitable habitats, driven by ecological or behavioural constraints. Migratory insects show an extraordinary capacity to traverse vast geographic ranges, as well as notable landscape features like mountains, deserts and oceans. Yet, their movements are not unrestricted: they are shaped by seasonal dynamics that dictate the feasibility of migration across these landscapes. Hemisphericity, the existence of inverted seasonal regimes and orientation cues in the two latitudinal hemispheres, has been proposed as a potential abiotic barrier involved in the diversification of migratory insects. Here, we use population genomic data to investigate patterns of diversification in migratory caper butterflies (Belenois spp.) across Africa. We identify a striking phylogeographic break around the equator in Belenois aurota, and emerging population structure between northern and southern African populations in Belenois creona, consistent with migratory divides aligned with hemispheric barriers. These divergences largely predate the Last Glacial Maximum, when major environmental changes such as contractions-expansions of equatorial rainforests and savannahs occurred. This reinforces the hypothesis that long-term abiotic factors, such as hemisphericity, had a role in limiting north-south dispersal. Given the absence of detectable gene flow detected even in sympatric populations of B. aurota in their contact zone in Kenya, Uganda, and Tanzania, we argue that populations from the Northern and Southern Hemispheres represent different species, and reinstate the taxon Belenois syrinx (Wallengren 1860) reinst. stat. for the Southern African lineage. Our findings provide genomic evidence of migratory divides in insects, which surprisingly emerge in the absence of physical barriers in the landscape, highlighting a role of hemisphere-specific adaptations in driving reproductive isolation and diversification in migratory insects.

DNA barcoding has become a cornerstone for species identification and biodiversity monitoring, enabling applications from ecological research to conservation and environmental policy. The International Barcode of Life (iBOL) provides global coordination, but national nodes are essential for implementing barcoding at scale, building local capacity and translating scientific advances into practice. This paper synthesises experiences from 20 countries (17 in Europe), drawing on a survey and a workshop conducted under the Horizon Europe Biodiversity Genomics Europe project. We examine how national nodes are initiated, governed and sustained and identify common challenges, such as defining scope, securing funding, harmonising methods and engaging stakeholders. Most nodes were initiated by research communities and operate as informal networks with heterogeneous governance and staffing models. Key priorities include constructing comprehensive DNA barcode reference libraries, aligning activities with biomonitoring needs and promoting FAIR and CARE data principles. We highlight strategies for capacity building, methodological standardisation and stakeholder engagement, alongside approaches for diversifying funding and strengthening communication. Based on these insights, we present ten practical recommendations to guide the establishment and long-term success of national DNA barcoding nodes. Strengthening these infrastructures will enhance Europe’s ability to deliver robust DNA-based biodiversity monitoring, underpin metabarcoding and metagenomic studies and contribute to global efforts in species discovery, conservation and environmental management.

Conservation biases have been documented since the first emergence of the concept of biodiversity in the 1980s,1,2,3 showing a systematic disproportion in the allocation of research and conservation efforts among taxa.4,5,6,7,8,9,10,11 One factor underlying this disproportion, gaining prominence in recent literature, is species' perceived beauty, shaped by human visual preferences.12,13,14,15,16,17 Here, we integrate a large-scale survey of the perceived beauty of European butterflies yielding >21,000 survey completions from >100 countries into a time-explicit network linking species' beauty, public attention, research and conservation efforts, and the EU regulatory framework. We found that species beauty is consistently associated with public attention, research, and conservation efforts in a temporally structured pattern compatible with a cumulative beauty bias. Research effort and public attention concentrate on widespread and visually attractive species, whereas species included in the legal conservation framework, particularly the Convention on the Conservation of European Wildlife and Natural Habitats (hereafter, Bern Convention, BC, 1979)18 and the EU Habitats Directive (hereafter, HD, 1992)19 are disproportionately represented by visually appealing and historically protected taxa. Because these frameworks guide funding and management actions, early associations between species beauty and BC/HD inclusion have contributed to long-lasting institutional patterns in butterfly research and conservation. By contrast, European IUCN Red Lists20,21 do not overrepresent beautiful species and identify more inconspicuous taxa as threatened. This mismatch reveals a tension between scientific assessments of extinction risk and historically embedded conservation priorities. Our findings suggest that recognizing beauty bias is vital for aligning conservation with actual ecological urgency. VIDEO ABSTRACT.

Project Psyche is a trans-national initiative to generate and study chromosome-level reference genomes of all ca. 11,000 described species of Lepidoptera (butterflies and moths) found in Europe. The Project Psyche community encompasses diverse researchers, amateur lepidopterists, practitioners, and industry experts united by a common vision of the importance of genomics for Lepidoptera. Lepidoptera are at the forefront of biodiversity genomics with genomes for over 1,000 species already generated - the highest number across all eukaryotic orders. Here, we outline how Project Psyche is generating and harnessing these genomes. This pan-European catalogue of openly accessible lepidopteran genomes will transform our understanding of evolution and ecology, inform conservation, and foster advances in pest management.

Ongoing global change is leading to the widespread redistribution of species1,2. Assessments of shifts in species geographic ranges, however, remain taxonomically biased and geographically limited2, especially for insects. We conducted a global synthesis on butterfly range shifts using a combination of multi-lingual review in 15 languages and expert assessments, compiling data on range shifts for 1758 species (10% of described butterfly species) from 109 countries over the last three decades. In 5 of these countries, over 50% of butterfly species shifted their ranges. Overall, most species showed horizontal range expansion (81%), while 27% contracted their range and 22% shifted in elevation. Expansions were primarily reported in tropical species-rich regions, while 19% of species displayed multiple, concurrent range shifts in different countries, highlighting the complexity of these responses. In addition, there was also variation across families - while one-third of the documented species are nymphalids, pierids and papilionids had the highest proportion of species, experiencing range shift. We pinpoint nine drivers of species redistribution, with climate change and severe weather as most prominent. We suggest a future-focused conservation strategy that emphasises monitoring expansion in underrepresented regions and megadiverse countries, leveraging citizen science, and integrating range shifts into conservation planning.

Batesian mimicry manifests in amazing forms, yet empirical studies quantifying its efficiency in nature are virtually absent. Lepidopterans include striking mimics of aposematic hymenopterans. Imitations may include not only visual components, but also acoustic and chemical signaling. We evaluated whether hymenopteran-mimicking clearwing moths (Lepidoptera: Sesiidae) and diurnal hawkmoths (Lepidoptera: Sphingidae) complement visual anti-predator signaling with acoustical mimicry. Through field-based experiments, we then compared the response of an avian predator, the European robin (Erithacus rubecula), to hymenopteran models and their lepidopteran mimics. Our work contradicts the assumption that aposematism and Batesian mimicry provide generalized protection to insects, paving the way for comparative studies involving a broader range of predators. We verified two predictions: (1) robins discriminate among different models based on their perceived risk, with avoidance behavior occurring in response to more harmful stimuli; (2) predators respond similarly within each studied pair of model and mimic. We demonstrated a clear distinction in the reaction of robins to the hornet Vespa crabro and its mimic, the hornet clearwing Sesia apiformis, in comparison to all other tested species, strongly indicating that the presence of the hornet and hornet mimic deterred the birds.

Nests of ecosystem-dominant eusocial insects like ants and termites offer stable, nutrient-rich, and protected habitats that may be exploited by other organisms. Several arthropod lineages managed to breach nest defenses and become inquilines, mutualists, predators, parasitoids, or social parasites.1-4 However, achieving social integration requires extreme morphological, behavioral, and physiological adaptations.5 Among flies, only scuttle flies (Phoridae) are well-known social parasites,2 although interactions with termites (predation, scavenging, and putative parasitism) have also been mentioned in anecdotal reports for blow flies (Rhiniinae6-10 and Bengaliinae11-13) and flesh flies (Miltogramminae14-16). Here, we report a fly larva found to be socially integrated within nests of the termite Anacanthotermes ochraceus (Burmeister) in Morocco. Behavioral, chemical, and morphological analyses show that colony integration, including communication and grooming, is achieved through unique adaptations. The chemical profiles of the fly larvae perfectly match those of the termites at the colony level. Notably, the posterior part of the larvae mimics a termite's head, and the long papillae that imitate the termites' antennae surround the entire body. Based on phylogenomics, we show that the larvae belong to the blow fly genus Rhyncomya (Calliphoridae: Rhiniinae). Our results support the hypothesis that the enigmatic blow fly subfamily Prosthetosomatinae (only known from larvae observed in termite nests17-20) is Rhiniinae. Thus, we demonstrate that the diverse schizophoran flies evolved social integration independently from the 150-million-year- diverged Phoridae radiation. This discovery sheds light on the repeated evolution of termitophily within the order Diptera.