Pollinators play a crucial role in ecosystems globally, ensuring the seed production of most flowering plants. They are threatened by global changes and knowledge of their distribution at the national and continental levels is needed to implement efficient conservation actions, but this knowledge is still fragmented and/or difficult to access. As a step forward, we provide an updated list of around 3000 European bee and hoverfly species, reflecting their current distributional status at the national level (in the form of present, absent, regionally extinct, possibly extinct or non‐native). This work was attainable by incorporating both published and unpublished data, as well as knowledge from a large set of taxonomists and ecologists in both groups. After providing the first National species lists for bees and hoverflies for many countries, we examine the current distributional patterns of these species and designate the countries with highest levels of species richness. We also show that many species are recorded in a single European country, highlighting the importance of articulating European and national conservation strategies. Finally, we discuss how the data provided here can be combined with future trait and Red List data to implement research that will further advance pollinator conservation.

In this paper we analyzed environmental differentiation of closely related species from the Merodon ruficornis group. By applying principal component analysis (PCA) and environmental niche modelling (ENM)-based techniques, we estimated the level of niche divergence of closely related species. Our results indicate that ecology has an important role in the diversification process in related species from the M. ruficornis group. Distribution patterns of all analyzed species are mainly affected by the limiting effects of the temperature of the coldest quarter and month, as well as by the precipitation of the wettest and driest quarters. Our results demonstrated that among all related species, with the exception of M. ovaloides, overall or partial divergence in environmental space is present. Importantly, the results indicate that the environmental niches of all endemic species are restricted to smaller parts of the environmental space. In the case of niche overlap, the niches of endemic species are placed along the border of the realized niche of the widespread related species. For species in which distribution is not limited by geographical barriers, environmental preferences could be considered as limiting factors for further expansion, as in the case of M. alexandri, a lowland species with very strict climatic adaptations. Knowledge about the environmental factors that might influence the diversification process can provide an explanation for the high diversity in other Merodon species groups.

Descriptions are given of three new species of Merodon Meigen (Diptera: Syrphidae) in the nigritarsis species group from the Middle East: Merodon angustus Vujić et Radenković n. sp., Merodon hakkariensis Vujić et Radenković n. sp. and Merodon quadraticus Vujić et Radenković n. sp. In addition, diagnostic characters are given for the nigritarsis group and distribution maps are presented for the new species and closely related taxa.

The genusMerodonMeigen, 1803 is distributed across the Palaearctic and Afrotropical Regions. The present work summarizes the knowledge from recent taxonomic and systematic revisions and includes an identification key for the five monophyletic lineages (namelyalbifrons,aureus,avidus-nigritarsis,desuturinusandnatans), 24 species groups, two species subgroups and 10 unplaced species, along with diagnosis and illustrations. A list of 234 taxa, including 194 described and 40 undescribed species, is appended. Most of the species are distributed in the Palaearctic (209 taxa, 181 described), while 27 species (14 described) are known from the Afrotropical Region. Three lineages (aureus,desuturinusandnatans) are present in the Afrotropical Region, as well as in the Palaearctic. The Afrotropicalmelanocerusspecies group of thedesuturinuslineage and thebombiformisspecies group of theaureuslineage are endemic to the Afrotropical Region, and all other species groups belong to the Palaearctic fauna. Thealbifronslineage contains six species groups (albifrons,constans,equestris,geniculatus,ruficornisandrufus) and two unplaced taxa. Theaureuslineage includes five species groups (aureus,bombiformis,funestus,nanusandspinitarsis). Theavidus-nigritarsislineage is divided into 10 species groups (aberrans,aurifer,avidus,clavipes,fulcratus,italicus,nigritarsis,pruni,serrulatusandtarsatus) and eight unplaced taxa. Thedesuturinuslineage contains two species groups: the Afrotropicalmelanocerusgroup, with themelanocerusandplanifaciessubgroups plus the speciesM. cuthbertsoniCurran, 1939, and the Palaearcticmurorumspecies group. Thenatanslineage consists of thenatansspecies group plus the speciesM. segetumFabricius, 1794.

Two new remarkable species of the genus Merodon Meigen (Diptera: Syrphidae) are described from biodiversity hotspots in the Middle East: Merodon eumerusi Vujić, Radenković et Likov sp. n. and Merodon mixtum Vujić, Radenković et Likov sp. n. Although M. eumerusi, from the Mountains of Central Asia, belongs clearly to the lineage of M. avidus-nigritarsis, it possesses some unique features within the genus that are also present in other Merodontini genera. M. mixtum, from the Irano-Anatolian mountains, has typical characters of different species groups within the M. albifrons lineage. Here, we discuss the unusual apomorphic characters of these newly discovered taxa and highlight the need for further analyses to ascertain the phylogenetic relationships within the tribe Merodontini and the genus Merodon.

The phytophagous hoverfly genusMerodonMeigen, 1803 (Diptera, Syrphidae), which comprises more than 160 species distributed in Palaearctic and Afrotropical regions, can be differentiated into multiple groups of species that harbor high levels of hidden diversity. In this work, theserrulatusspecies group ofMerodonis revised, providing an illustrated key to species, a detailed discussion on the taxonomic characters and a morphological diagnosis, including also the first data about the preimaginal morphology of this species group. The study includes characteristics of the 13 species of theM. serrulatusgroup, along with the available distributional data. Moreover, descriptions are provided for seven new species, namelyM. defectusVujić, Likov & Radenkovićsp. nov.,M. disjunctusVujić, Likov & Radenkovićsp. nov.,M. mediumVujić, Likov & Radenkovićsp. nov.,M. nigrocapillatusVujić, Likov & Radenkovićsp. nov.,M. nigropunctumVujić, Likov & Radenkovićsp. nov.,M. opacusVujić, Likov & Radenkovićsp. nov., andM. trianguloculusVujić, Likov & Radenkovićsp. nov.In addition, the taxaM. serrulatus(Wiedemann in Meigen, 1822),M. bequaertiHurkmans, 1993,M. hirsutusSack, 1913,M. kawamuraeMatsumura, 1916,M. sacki(Paramonov, 1936) andM. sophronHurkmans, 1993 are redefined and redescribed. Following a detailed study of the type material sourced from different entomological collections, the status of all available taxa related toM. serrulatusis revised and a new synonymy is proposed:M. tenerSack, 1913syn. nov.(junior synonym ofM. serrulatus). The identity ofM. trizonus(Szilády, 1940) could not be assessed as the type specimens are lost. Thus, the nameM. trizonusis considered asnomen dubium. The monophyly and composition of this species group are assessed through Maximum Parsimony and Maximum Likelihood analyses of the mitochondrial COI and nuclear 28S rRNA gene sequences.