The Extraordinary Diversity of Merodon avidus Complex (Diptera: Syrphidae)-Adding New Areas, New Species and a New Molecular Marker.

In this paper, the Merodon avidus (Diptera, Syrphidae) species complex was revised, whereupon we discovered and described four new species for science: Merodon atroavidus Vujic, Radenkovic et Likov sp. nov., M. magnus Vujic, Kocis Tubic et Acanski sp. nov., M. nigroscutum Vujic, Radenkovic et Likov sp. nov. and M. pseudomoenium Vujic, Kocis Tubic et Acanski sp. nov. An integrative taxonomy approach was used to delimit species boundaries. Two molecular markers (the mitochondrial COI gene and nuclear 28S rRNA gene-newly analysed marker for the complex) and geometric morphometry of the wing shape, together with morphological data and distribution, successfully separated all species from the complex. The morphological variability of the analysed species is described and discussed and an illustrated diagnostic key for typical morpho-forms of species from the M. avidus complex is presented. A distribution map of all investigated species from the complex is provided. The level of endemicity of the M. avidus complex was discussed.

An updated checklist of the hoverflies (Diptera: Syrphidae) of Slovenia.

This paper is an updated checklist of the hoverflies of Slovenia. Since the last checklist of 274 species published by de Groot & Govedic in 2008, a large number of additional specimens have been collected and studied. In the present study, 42 species are reported for the first time for the Slovenian hoverfly fauna. Sphegina sublatifrons Vujic, 1990 is deleted from the Slovenian list. In total, 362 species from 77 genera are reported. According to the IUCN European Red List of Hoverflies, 29 species are classified as Endangered, 9 as Vulnerable, 19 as Near Threatened, 302 as Least Concern and 3 as Data Deficient. The distribution of species per region in Slovenia is presented. With 243 species, Upper Carniola hosts the largest number of registered species, followed by Central Slovenia (233 spp.), Gorizia (230 spp.), Savinja and Littoral Inner-Carniola (both with 173 spp.), Coastal-Karst (133 spp.), Southeast Slovenia (71 spp.), Drava (60 spp.), Carinthia (56 spp.), Lower Sava (52 spp.), Mura (47 spp.) and Central Sava (8 spp.). A significant increase in the number of new records has been noted in recent decades, and the possible reasons for this trend are also discussed here.

Recent fire in a Mediterranean ecosystem strengthens hoverfly populations and their interaction networks with plants.

Fire affects many critical ecological processes, including pollination, and effects of climate change on fire regimes may have profound consequences that are difficult to predict. Considerable work has examined effects of fire on pollinator diversity, but relatively few studies have examined these effects on interaction networks including those of pollinators other than bees. We examined the effects of a severe wildfire on hoverfly pollinators in a Mediterranean island system. Using data collected over 3 consecutive years at burnt and unburnt sites, we documented differences in species diversity, abundance, and functional traits, as well as hoverfly interactions with flowering plants. Hoverfly abundance and species richness peaked during the first post-fire flowering season (year 1), which coincided with the presence of many opportunistic species. Also in year 1, hoverfly pollination networks were larger, less specialized, more nested, and less modular at burnt (vs. unburnt) sites; furthermore, these networks exhibited higher phylogenetic host-plant diversity. These effects declined over the next 2 years, with burnt and unburnt sites converging in similarity to hoverfly communities and interaction networks. While data obtained over 3 years provide a clear timeline of initial post-fire recovery, we emphasize the importance of longer-term monitoring for understanding the responses of natural communities to wildfires, which are projected to become more frequent and more destructive in the future.

High species turnover and unique plant-pollinator interactions make a hyperdiverse mountain.

We studied α- and ß-diversity of pollinators, flowering plants and plant-pollinator interactions along the altitudinal gradient of Mt. Olympus, a legendary mountain and biodiversity hotspot in Central Greece. We explored 10 study sites located on the north-eastern slope of the mountain, from 327 to 2596 m a.s.l. Insect surveys were conducted once a month using hand netting (years 2013, 2014 and 2016), and they were combined with recordings of flowering plant diversity (species richness and flower cover). We then calculated α- and ß-diversity of pollinators, plants in flower and plant-pollinator interactions, and explored their demographic response along the altitudinal gradient. Alpha diversity of pollinators, plants and plant-pollinator interactions were altitude dependent; α-diversity of all pollinators, bees, non-bumblebee bees, bee flies and butterflies showed linear declines with altitude, whereas those of hoverflies and bumblebees showed unimodal patterns. Beta diversity and its turnover component of all pollinators, hoverflies, bees, bumblebees, non-bumblebee bees, butterflies and plants showed linear increases, whereas those of bee flies and of plant-pollinator interactions varied independently from the pairwise altitudinal difference. The high dissimilarity and uniqueness of pollination networks, which is probably a result of the high biodiversity and endemism of Mt. Olympus, is driven by species turnover and the formation of new interactions between new species. Contrasting to the monotonic decline of the remaining groups, the unimodal patterns of hoverfly and bumblebee α-diversity are probably the effect of a higher tolerance of these groups to high-altitude environmental conditions. Our findings highlight that the high turnover of species and of pollination interactions along the altitudinal gradient are the mainstay of hyperdiverse mountains, a fact that conveys important historical, ecological and conservational implications.

Characterization of preimaginal developmental stages of two cryptic South African species of the Merodon planifacies complex (Diptera: Syrphidae: Eristalinae: Merodontini), with differentiation through morphometry analysis.

Merodon capi Vujic et Radenkovic, 2020 and Merodon roni Radenkovic et Vujic, 2020 are two cryptic species belonging to the Merodon planifacies Bezzi, 1915 species complex that have recently been described, with the differences between them being revealed by molecular and geometric morphometry studies of adult specimens. In the present study, the preimaginal morphology of both species is described and displayed, with the material used corresponding to samples taken from bulbs of Merwilla plumbea (Lindl.) Speta plants at two locations in KwaZulu-Natal province (South Africa). The preimaginal stages were compared, looking for morphological evidence supporting species divergence. Linear and geometric morphometric analyses of the larval posterior respiratory process were conducted for the first time and the results of these analyses support the separation of the two taxa. Information about the life cycle and the relation with the host plant is also provided. In addition, we carried out a preliminary study of the adult feeding requirements of the species, based on the description of the mouthparts and an analysis of the pollen present in the gut and on the integument of adults. The results of the study supports a close relationship between the preimaginal stages and plant species of the Hyacinthaceae family.

Contribution to the knowledge of the bee fauna (Hymenoptera, Apoidea, Anthophila) in Serbia.

The current work represents summarised data on the bee fauna in Serbia from previous publications, collections, and field data in the period from 1890 to 2020. A total of 706 species from all six of the globally widespread bee families is recorded; of the total number of recorded species, 314 have been confirmed by determination, while 392 species are from published data. Fourteen species, collected in the last three years, are the first published records of these taxa from Serbia: Andrenabarbareae (Panzer, 1805), A.clarkella (Kirby, 1802), A.fulvicornis (Schenck, 1853), A.intermedia (Thomson, 1870), A.lapponica (Zetterstedt, 1838), A.pandellei (Pérez, 1895), A.paucisquama (Noskiewicz, 1924), A.simillima (Smith, 1851), Panurginusherzi (Morawitz, 1892), Epeoloidescoecutiens (Fabricius, 1775), Nomadaleucophthalma (Kirby, 1802), Chelostomanasutum (Pérez, 1895), Hoplitisclaviventris (Thomson, 1872), and Dasypodapyrotrichia (Förster, 1855). Almost all the species recorded so far in Serbia belong to the West-Palaearctic biogeographical region, except Megachilesculpturalis (Smith, 1853), which is an alien invasive species native to East Asia. According to the European Red List of bees, 221 species listed in this paper were assessed as Data Deficient; threatened species mostly belong to the families Apidae with 13 species, Colletidae with eight species, and Halictidae with five species. This study contributes to the knowledge of the distribution of bee species in Europe. The present work provides a baseline for future research of wild bee diversity in Serbia and neighbouring regions at the local and regional levels, and a basis for their conservation.

Taxonomic complexity in the genus Merodon Meigen, 1803 (Diptera, Syrphidae).

The genus Merodon Meigen, 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 (namely albifrons, aureus, avidus-nigritarsis, desuturinus and natans), 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, desuturinus and natans) are present in the Afrotropical Region, as well as in the Palaearctic. The Afrotropical melanocerus species group of the desuturinus lineage and the bombiformis species group of the aureus lineage are endemic to the Afrotropical Region, and all other species groups belong to the Palaearctic fauna. The albifrons lineage contains six species groups (albifrons, constans, equestris, geniculatus, ruficornis and rufus) and two unplaced taxa. The aureus lineage includes five species groups (aureus, bombiformis, funestus, nanus and spinitarsis). The avidus-nigritarsis lineage is divided into 10 species groups (aberrans, aurifer, avidus, clavipes, fulcratus, italicus, nigritarsis, pruni, serrulatus and tarsatus) and eight unplaced taxa. The desuturinus lineage contains two species groups: the Afrotropical melanocerus group, with the melanocerus and planifacies subgroups plus the species M. cuthbertsoni Curran, 1939, and the Palaearctic murorum species group. The natans lineage consists of the natans species group plus the species M. segetum Fabricius, 1794.

Descriptions of two new species of the genus Paragus Latreille (Diptera: Syrphidae), with a key to males of all South African species.

Two new species of the genus Paragus Latreille, 1804 are described from the Republic of South Africa: Paragus longipilus Tot, Vujic et Radenkovic sp. nov. and Paragus megacercus Tot, Vujic et Radenkovic sp. nov. These new species belong to the subgenus Pandasyopthalmus Stuckenberg, 1954a. Paragus longipilus sp. nov. is a member of the P. jozanus group, whereas Paragus megacercus sp. nov. belongs to the P. tibialis group. The taxonomic status of Paragus chalybeatus Hull, 1964 is revised and proposed as synonym of Paragus punctatus Hull, 1949. Additionally, an identification key to males of the South African species of Paragus is provided. Results of the present study confirm a significant level of endemism of Paragus in the Afrotropical Region (12 out of 29).

Three new hoverfly species from Greece (Diptera: Syrphidae).

An ongoing investigation on the Greek hoverfly fauna using adult morphology has revealed new species within three genera. In this study, the knowledge of the Mediterranean hoverfly fauna has been enhanced by describing the following species: Cheilosia candida Vujic et Radenkovic sp. n. (Pindos Mountains), Paragus thracusi Radenkovic, Likov et Vujic sp. n. (Rhodope Mountains) and Psilota aegeae Vujic, Ståhls et Smit sp. n. (Lesvos island). Diagnosis of new species, as well as identification keys to the Mediterranean species of the subgenus Convocheila Barkalov of Cheilosia Meigen and the European species of the genus Psilota Meigen have been provided. Additionally, mtDNA COI barcodes for the members of the Psilota atra group (except Psilota nana Smit et Vujic) have been given. In addition, the taxonomic status of Psilota anthracina Meigen has been discussed.

Revision of the Merodon serrulatus group (Diptera, Syrphidae).

The phytophagous hoverfly genus Merodon Meigen, 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, the serrulatus species group of Merodon is 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 the M. serrulatus group, along with the available distributional data. Moreover, descriptions are provided for seven new species, namely M. defectus Vujic, Likov & Radenkovic sp. nov., M. disjunctus Vujic, Likov & Radenkovic sp. nov., M. medium Vujic, Likov & Radenkovic sp. nov., M. nigrocapillatus Vujic, Likov & Radenkovic sp. nov., M. nigropunctum Vujic, Likov & Radenkovic sp. nov., M. opacus Vujic, Likov & Radenkovic sp. nov., and M. trianguloculus Vujic, Likov & Radenkovic sp. nov. In addition, the taxa M. serrulatus (Wiedemann in Meigen, 1822), M. bequaerti Hurkmans, 1993, M. hirsutus Sack, 1913, M. kawamurae Matsumura, 1916, M. sacki (Paramonov, 1936) and M. sophron Hurkmans, 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 to M. serrulatus is revised and a new synonymy is proposed: M. tener Sack, 1913 syn. nov. (junior synonym of M. serrulatus). The identity of M. trizonus (Szilády, 1940) could not be assessed as the type specimens are lost. Thus, the name M. trizonus is considered as nomen 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.

Stability and changes in the distribution of Pipiza hoverflies (Diptera, Syrphidae) in Europe under projected future climate conditions.

Climate change is now considered a significant threat to terrestrial biodiversity. Species distribution models (SDMs) are among the modern tools currently used to assess the potential impacts of climate change on species. Pipiza Fallén, 1810 is a well known aphidophagous hoverfly genus (Diptera, Syrphidae) at the European level, for which sampling has been conducted across the region, and long-term databases and geo-referenced datasets have been established. Therefore, in this work, we investigated the potential current distributions of the European species of this genus and their response to future climate change scenarios, as well as evaluated stability in their ranges and potential changes in species-richness patterns. We applied three climate models (BCC_CSM1.1, CCSM4, HadGEM2-ES) to four representative concentration pathways (RCP 2.6, RCP 4.5, RCP 6.0, RCP 8.5) for two time frames (2050 and 2070). Our results show that the distribution of most Pipiza species may slightly differ under different climate models. Most Pipiza species were predicted not to be greatly affected by climate change, maintaining their current extent. Percentages of stable areas will remain high (above 50%) for the majority of studied species. According to the predicted turnover of species, northern Europe, could become the richest in terms of species diversity, thus replacing Central Europe as the current hot spot.

Two new European long-legged hoverfly species of the Eumerusbinominatus species subgroup (Diptera, Syrphidae).

Eumerus Meigen (Diptera, Syrphidae) is one of the most speciose hoverfly genera in Europe, with several species groups recognized within. As part of the tricolor group of species, a subgroup of long-legged representatives stands out. We name it Eumerusbinominatus subgroup and provide descriptions for two new European species which belong to this subgroup: E.grallator sp. nov. from mainland Spain and E.tenuitarsis sp. nov. from Lesvos and Evros, Greece. A key for all five recognized species of the binominatus subgroup is provided.

Two new enigmatic species of the genus Merodon Meigen (Diptera: Syrphidae) from the north-eastern Middle East.

Two new remarkable species of the genus Merodon Meigen (Diptera: Syrphidae) are described from biodiversity hotspots in the Middle East: Merodon eumerusi Vujic, Radenkovic et Likov sp. n. and Merodon mixtum Vujic, Radenkovic 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.

Moderate fire severity is best for the diversity of most of the pollinator guilds in Mediterranean pine forests.

Fire, a frequent disturbance in the Mediterranean, affects pollinator communities. We explored the response of major pollinator guilds to fire severity, across a fire-severity gradient at different spatial scales. We show that the abundance of all pollinator groups responded to fire severity, and that bees and beetles showed in addition a significant species-diversity response. Bees, sawflies, and wasps responded to fire severity at relatively small spatial scales (250-300 m), whereas flies and beetles responded at larger spatial scales. The response of bees, sawflies, and wasps was unimodal, as predicted by the intermediate disturbance hypothesis, whereas flies and beetles showed a negative response. A possible explanation is that the observed patterns (spatial scale and type of response) are driven by taxa-specific ecological and life-history traits, such as nesting preference and body size, as well as the availability of resources in the postfire landscape. Our observational study provides an insight into the effect of fire severity on pollinators. However, future research exploring the explicit link between the pre- and postfire landscape structure and pollinator traits and responses is required for further establishment and understanding of cause-effect relationships.

Pupal stages of three species of the phytophagous genus Merodon Meigen (Diptera: Syrphidae).

plants, are mostly unknown. All known immature stages of Merodon feed on underground storage organs (bulbs, rhizomes and corms) of geophytes of the families Asparagaceae, Iridaceae and Amaryllidaceae. Of 160 known Merodon species, to date, the pupal stages have been described for only four: M. equestris (Fabricius), M. bombiformis Hull, M. luteihumerus Marcos-García, Vujic Mengual, and M. geniculatus Strobl. During field investigations in Derdap National Park, Serbia, Merodon puparia were found in the ground near the bulbs of Ornithogalum umbellatum L. (Asparagaceae). DNA barcoding revealed that they belonged to the species M. aureus Fabricius and M. avidus (Rossi). Analysis of museum material from the Bavarian State Collection of Zoology in Germany revealed the puparium of an additional species, M. rufus Meigen. In our study we provide for the first time descriptions of the puparia of these three Merodon species. The main diagnostic morphological characters of the pupal spiracles and posterior respiratory processes are described using scanning electron microscopy, and cephalopharyngeal skeletons using binocular microscopy. In addition, puparium morphology of M. aureus, M. avidus and M. rufus is compared with known puparia of four other Merodon species and with the third larval stage of M. hurkmansi Marcos-García, Vujic Mengual.

Revision of the Palaearctic species of the Merodon desuturinus group (Diptera, Syrphidae).

This revision of material belonging to the Merodon desuturinus group from the Palaearctic Region resulted in the delimitation of four species: Merodon cabanerensis Marcos-García, Vujic & Mengual, 2007; Merodon desuturinus Vujic, Simic & Radenkovic, 1995; Merodon neolydicus Vujic, nom. n.; and Merodon murorum Fabricius, 1794. Merodon murorum is redescribed. A neotype for Merodon auripilus Meigen, 1830 is designated, which is a new junior synonym of Merodon murorum. The related Afrotropical species Merodon cuthbertsoni Curran, 1939 is re-evaluated and compared to its sibling Palaearctic taxon Merodon desuturinus. An identification key for the Merodon desuturinus group is provided.

Close relatives of Mediterranean endemo-relict hoverflies (Diptera, Syrphidae) in South Africa: Morphological and molecular evidence in the Merodon melanocerus subgroup.

An ongoing study of the genus Merodon Meigen, 1803 in the Republic of South Africa (RSA) has revealed the existence of new species related to M. melanocerus Bezzi, 1915. The M. melanocerus subgroup belongs to the Afrotropical lineage of the M. desuturinus group. Revision of all available material from museums and detailed analyses of newly -collected specimens from our own expeditions to RSA resulted in delimitation of five species: M. capensis Hurkmans sp. n., M. commutabilis Radenkovic et Vujic sp. n., M. drakonis Vujic et Radenkovic sp. n., M. flavocerus Hurkmans sp. n. and M. melanocerus. In addition to classical morphological characters, sequences of the mitochondrial COI gene are provided for four related taxa. Results of molecular phylogenetic analyses supports monophyly of the M. desuturinus group and confirmed delimitation between species. Links between Palaearctic and Afrotropical faunas of this group, as well as possible evolutionary paths, are discussed. Based on phylogenetic analyses, four lineages (putative subgenera) have been recognized within the genus Merodon; besides the three previously established ones, albifrons+desuturinus, aureus (sensu lato) and avidus-nigritarsis, one new lineage named natans is distinguished.

Review of the Merodon albifasciatus Macquart species complex (Diptera: Syrphidae): the nomenclatural type located and its provenance discussed.

The Palaearctic Merodon geniculatus species group (Diptera, Syrphidae: Merodontini) currently comprises six Western Mediterranean species and four species with Eastern Mediterranean distribution. One of this group species, Merodon albifasciatus Macquart, 1842, is the only Merodon species listed from the Oriental Region. We discovered the lost holotype, which fit morphologically with European Merodon females of the M. albifasciatus species complex confirmed here and that occurs in the Palaearctic region. An integrative approach to the taxonomy of M. albifasciatus based on morphological and molecular evidences revealed the existence of two additional closely-related species in the Eastern Mediterranean area, M. luteofasciatus Vujic, Radenkovic Ståhls sp. nov. and M. neofasciatus Ståhls Vujic sp. nov.. The females of these three species can only be separated by molecular and distributional data. With the aim of stabilising species concepts within the complex, the taxon distributed in mainland Greece, including the Peloponnese was associated to the old female holotype of M. albifasciatus. The identity of Merodon fractipes Paramonov, described from Rhodes Island (Greece) as subspecies of M. geniculatus Strobl in Czerny Strobl, could not be resolved as the type specimen is lost. Thus the name M. fractipes is suppressed as nomen dubium. We discuss the distribution of the species of M. albifasciatus complex, identify host plants of M. neofasciatus, and provide an identification key to males of Eastern Mediterranean species of Merodon geniculatus group.

Three new Eastern-Mediterranean endemic species of the Merodon aureus group (Diptera: Syrphidae).

The Merodon aureus group (Diptera: Syrphidae: Eristalinae) comprises a number of different subgroups and species complexes, including the M. bessarabicus subgroup, which is revised here. In this study, we present an identification key to species complexes and species within the M. bessarabicus subgroup and focus on clarifying the taxonomic status of previously described species within this subgroup, based on a study of the type material. Merodon flavicornis Macquart, a species with an unknown type locality, is re-evaluated and recognized as a valid Western Mediterranean species from France. We describe a new species, M. adriaticus sp. n., from M. bessarabicus subgroup, as well as another two species with a clearly separate position within the M. aureus group due to their distinct morphological features: M. nisi sp. n. and M. robustus sp. n.. Results of the present study indicate the high diversity and endemism levels of the genus Merodon in Europe.

Ecological networks are more sensitive to plant than to animal extinction under climate change.

Impacts of climate change on individual species are increasingly well documented, but we lack understanding of how these effects propagate through ecological communities. Here we combine species distribution models with ecological network analyses to test potential impacts of climate change on >700 plant and animal species in pollination and seed-dispersal networks from central Europe. We discover that animal species that interact with a low diversity of plant species have narrow climatic niches and are most vulnerable to climate change. In contrast, biotic specialization of plants is not related to climatic niche breadth and vulnerability. A simulation model incorporating different scenarios of species coextinction and capacities for partner switches shows that projected plant extinctions under climate change are more likely to trigger animal coextinctions than vice versa. This result demonstrates that impacts of climate change on biodiversity can be amplified via extinction cascades from plants to animals in ecological networks.