Revisions of the clavipes and pruni species groups of the genus Merodon Meigen, 1803 (Diptera, Syrphidae).

This study focuses on the avidus-nigritarsis lineage within the genus Merodon, exploring morphological, genetic, and distributional aspects of two related assemblies within this lineage: the clavipes and pruni species groups. An integrative taxonomic approach was followed to ensure comprehensive species identification and validation, using adult morphology, wing geometric morphometrics, and genetic analysis of the mtDNA COI gene. In the clavipes group, seven species were identified, including three new species: M.aenigmaticus Vujic, Radenkovic & Likov, sp. nov., M.latens Vujic, Radenkovic & Likov, sp. nov., and M.rufofemoris Vujic, Radenkovic & Likov, sp. nov. In the pruni group, our revision revealed a new species, M.aequalis Vujic, Radenkovic & Likov, sp. nov., and the revalidation of Merodonobscurus Gil Collado, 1929, stat. rev. Merodonpallidus Macquart, 1842 is redescribed. Diagnoses, identification keys to species, and distribution maps are provided, and neotypes for Syrphusclavipes Fabricius, 1781 and Merodonquadrinotatus (Sack, 1931) are designated. Additionally, the following new synonyms are proposed: M.clavipesalbus syn. nov., M.clavipesater syn. nov., M.clavipesniger syn. nov., and M.splendens syn. nov. are junior synonyms of M.clavipes; and M.veloxarmeniacus syn. nov. and M.veloxanathema syn. nov. are junior synonyms of M.velox.

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.

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.

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.

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.

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).

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.

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.

Bee (Hymenoptera: Apoidea) and hoverfly (Diptera: Syrphidae) pollinators in Pannonian habitats of Serbia, with a description of a new Eumerus Meigen species (Syrphidae).

The diversity of bee (Hymenoptera: Apoidea) and hoverfly (Diptera: Syrphidae) pollinators from ten localities in Vojvodina, Serbia was surveyed. Among different types of Pannonian habitat (grasslands, heathland and scrub, woodland and forest habitats) all localities were categorised as forest and steppe. They were in protected areas, mostly undisturbed by human activity. Censuses of pollinators took place from 30 March to 10 October, 2014. We recorded 218 pollinator species; 135 bee species (42 Halictidae; 32 Apidae; 29 Andrenidae; 24 Megachilidae; 7 Colletidae; 1 Melittidae) and 83 species of hoverflies. We describe a new species of hoverfly, Eumerus pannonicus sp. nov., and compare it to other similar species. Based on our study, the Special Nature Reserve of Pasnjaci Velike Droplje is critical for the conservation of this new Eumerus-being only found at this locality-and other species such as Chrysotoxum lineare (Zetterstedt), which is rare in Europe and protected under Serbian legislation. The highest numbers of bee species were recorded in the Deliblato and Subotica sand areas (40 and 32, respectively), while Fruska Gora Mountain and the Vrsac Mountains harboured the highest number of hoverfly species.

Molecular and Morphological Inference of Three Cryptic Species within the Merodon aureus Species Group (Diptera: Syrphidae).

The Merodon aureus species group (Diptera: Syrphidae: Eristalinae) comprises a number of different sub-groups and species complexes. In this study we focus on resolving the taxonomic status of the entity previously identified as M. cinereus B, here identified as M. atratus species complex. We used an integrative approach based on morphological descriptions, combined with supporting characters that were obtained from molecular analyses of the mitochondrial cytochrome c oxidase I gene as well as from geometric morphometry of wing and surstylus shapes and environmental niche comparisons. All applied data and methods distinguished and supported three morphologically cryptic species: M. atratus stat. nov., M. virgatus sp. nov. and M. balkanicus sp. nov., which constitute the M. atratus species complex. We present an identification key for the sub-groups and species complexes of the M. aureus species group occurring in Europe, describe the taxa and discuss the utility of the applied methods for species delimitation. The estimated divergence times for the species splits of these taxa coincide with the Pleistocene Günz-Mindel interglaciation and the Great interglaciation (between the Ris and Mindel glacial periods).

Brachyopa minima (Diptera: Syrphidae), a new species from Greece with notes on the biodiversity and conservation of the genus Brachyopa Meigen in the Northern Aegean Islands.

An on-going study of the hoverfly fauna of the Northern Aegean Islands (Greece) has revealed the presence of four species of the genus Brachyopa Meigen. During the survey the following species were found: B. bicolor (Fallén), B. quadrimaculosa Thompson in Kaplan & Thompson, B. minima Vujic & Pérez-Bañón sp. nov. and an unidentified species very close to B. pilosa (Collin). Morphological characters and mitochondrial COI barcodes were used to link different life stages of B. minima, and to identify a larval specimen of B. bicolor. In this study adult and larval morphology and habitat preferences for B. minima are described. The description of larval morphology of B. bicolor and Brachyopa sp. aff. pilosa is amended too. An identification key to the adults of the B. quadrimaculosa group sensu Kassebeer (2002) in the Eastern Mediterranean (Greece, Israel and Turkey) is provided. The importance of specific microhabitats for the continued existence of these taxa is discussed.

Phylogeographic patterns of Merodon hoverflies in the Eastern Mediterranean region: revealing connections and barriers.

We investigated the phylogeographic patterns of Merodon species (Diptera, Syrphidae) in the Eastern Mediterranean. Ten species were sampled on five different islands and mainland sites as a minimum. All samples were screened for their mtDNA COI barcode haplotype diversity, and for some samples, we additionally generated genomic fingerprints. The recently established zoogeographic distribution categories classify these species as having (1) Balkan distribution; (2) Anatolian distribution; (3) continental areas and large islands distribution; and (4) with wide distribution. The ancestral haplotypes and their geographical localities were estimated with statistical parsimony (TCS). TCS networks identified as the ancestral haplotype samples that originated from localities situated within the distributional category of the species in question. Strong geographical haplotype structuring was detected for many Merodon species. We were particularly interested to test the relative importance of current (Aegean Sea) and past Mid-Aegean Trench) barriers to dispersal for Merodon flies in the Aegean. We employed phylogenetic ß-diversity (Pß total) and its partition in replacement (Pß repl) and richness difference (Pß rich) to test the importance of each explanatory variable (interisland distance, MAT, and island area) in interisland differences using partial Mantel tests and hierarchical partitioning of variation. ß-Analyses confirmed the importance of both current and past barriers to dispersal on the evolution of group. Current interisland distance was particularly important to explain the replacement of haplotypes, while the MAT was driving differences in richness of haplotypes, revealing the MAT as a strong past barrier whose effects are still visible today in the phylogenetic history of the clade in the Aegean. These results support the hypothesis of a highly restricted dispersal and gene flow among Merodon populations between islands since late Pleistocene. Additionally, patterns of phylogeographic structure deduced from haplotype connections and ISSR genome fingerprinting data revealed a few putative cases of human-mediated transfers of Merodon spp.

Revision of the species of the Merodon nanus group (Diptera: Syrphidae) including three new species.

The nanus group of the genus Merodon Meigen (Diptera, Syrphidae) is revised, yielding an illustrated key, a discussion of taxonomic characters and morphological diagnosis for the five species of this group. Three new cryptic species are described, Merodon kopensis Vujic et Hayat sp. n., M. neonanus Vujic et Taylor sp. n. and M. rasicus Vujic et Radenkovic sp. n. New diagnostic characters are given for M. nanus Sack and M. telmateia Hurkmans. In addition, environmental profiles for each investigated species have been defined and compared, and maps of distribution and richness created. Niche dissimilarity was found for each species. Eastern Anatolia and the southern Aegean region of Turkey are reported as the most species rich regions for the nanus group.