Taxonomic entities below the species level often pose difficulties for conservation practice, especially when they are ecologically distinct from the nominal species. Genomic tools provide the opportunity to study and potentially resolve such cryptic diversity. The Alcon blue butterfly Phengaris alcon species complex is such a cryptic example, comprising different ecotypes or even subspecies, one of them is the high elevation taxon P. rebeli from the European Alps. We sequenced a first reference genome for Phengaris alcon. Furthermore, we generated whole genome resequence data for individuals of three Swiss ecotypes, i.e., the low elevation P. alcon, the mid elevation and high elevation alpine P. rebeli and integrated genomic data from across Europe to study the relationship among these ecotypes. At a European scale, our results suggest that for the P. alcon complex, biogeography and the evolutionary context of diversification is more multifaceted than previously suggested, falling in the range of more recent ecological speciation. In Switzerland, the three ecotypes were genetically isolated with only limited current gene flow between them. Past gene flow, however, could have given rise to the mid elevation ecotype. Our findings emphasise that high elevation P. rebeli in the Alps should be treated as a distinct species. Our study highlights how the availability of reference genome assemblies allows to address so far open taxonomic questions in conservation research and that broadscale studies are needed to understand the biogeographic history of apparent diversification.

In this study we apply a new monitoring technique for butterflies in order to get more insights into the habitat use patterns of Erebia christi Rätzer 1890 (Nymphalidae: Satyrinae). This European endemic is a rare and very localized butterfly species, found alongside steep slopes in a restricted area in the Alps, at the border between Italy and Switzerland. Even though it was discovered almost 140 years ago, captivating the interest of many lepidopterists, there are still several aspects about the biology of E. christi that are not fully known. We selected two monitoring sites in Veglia–Devero Natural Park, Italy and tested whether E. christi was more likely to use rocky, almost vertical slopes than other types of habitat. Since this habitat was almost inaccessible to humans, we used the single rope access technique, in which field operators rappelled down the slopes to explore the rock faces. We demonstrate that the main characteristics of the typical habitat of E. christi are indeed very steep rock faces with grassy ledges where Festuca sp. plants are present. We also show that, E. christi is more abundant than it was previously thought, with populations that could probably be structured in a metapopulation system. Long-term monitoring with the rope access technique could represent an optimal method to provide key insights into the biology and ecology not only of E. christi but of other butterflies that use similar habitats. Finally, we propose the upgrading of its IUCN category from Vulnerable to Endangered at European level. Our findings demonstrate how appropriate, long-term monitoring can contribute to improve the scarce knowledge of the ecology of an elusive species, and to devise informed proposals regarding the management and protection of populations, especially for species of conservation concern.

Red Lists are very valuable tools in nature conservation at global, continental and (sub-) national scales. In an attempt to prioritise conservation actions for European butterflies, we compiled a database with species lists and Red Lists of all European countries, including the Macaronesian archipelagos (Azores, Madeira and Canary Islands). In total, we compiled national species lists for 42 countries and national Red Lists for 34 of these. The most species-rich countries in Europe are Italy, Russia and France with more than 250 species each. Endemic species are mainly found on the Macaronesian archipelagos and on the Mediterranean islands. By attributing numerical values proportionate to the threat statuses in the different national Red List categories, we calculated a mean Red List value for every country (cRLV) and a weighted Red List value for every species (wsRLV) using the square root of the country’s area as a weighting factor. Countries with the highest cRLV were industrialised (NW) European countries such as the Netherlands, Belgium, the Czech Republic and Denmark, whereas large Mediterranean countries such as Spain and Italy had the lowest cRLV. Species for which a Red List assessment was available in at least two European countries and with a relatively high wsRLV (≥ 50) are Colias myrmidone, Pseudochazara orestes, Tomares nogelii, Colias chrysotheme and Coenonympha oedippus. We compared these wsRLVs with the species statuses on the European Red List to identify possible mismatches. We discuss how this complementary method can help to prioritise butterfly conservation on the continental and/or the (sub-)national scale.

Twenty-nine butterfly species are listed on the Annexes of the Habitats Directive. To assist everyone who wants or needs to take action for one of these species, we compiled an overview of the habitat requirements and ecology of each species, as well as information on their conservation status in Europe. This was taken from the recent Red List and their main biogeographical regions (taken from the first reporting on Article 17 of the Directive). Most important are the Dos and Don'ts, which summarize in a few bullet points what to do and what to avoid in order to protect and conserve these butterflies and their habitats.