Research Article |
Corresponding author: Ante Vujić ( ante.vujic@dbe.uns.ac.rs ) Academic editor: Ximo Mengual
© 2021 Ante Vujić, Snežana Radenković, Laura Likov, Sanja Veselić.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Vujić A, Radenković S, Likov L, Veselić S (2021) Taxonomic complexity in the genus Merodon Meigen, 1803 (Diptera, Syrphidae). ZooKeys 1031: 85-124. https://doi.org/10.3897/zookeys.1031.62125
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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.
Identification key, integrative taxonomy, lineages, Merodon, morphology, species groups, Syrphidae
The genus Merodon Meigen, 1803 is one of the most species-rich hoverfly genera, distributed across the Palaearctic and Afrotropical Regions (
The genus Merodon was described by
In Europe, Merodon is the most speciose genus with 120 described species (152 including Turkey) (
The genus Merodon was classified into more than 20 monophyletic species groups, half of which were addressed in
Nowadays, with the advent of molecular and morphometric techniques, an integrative taxonomic framework has become the standard to study the taxonomy of genus Merodon. Combining molecular characters (mtDNA cytochrome c oxidase subunit I (COI) and the nuclear 28S rRNA genes) with morphological traits (geometric wing morphometry, surstylus shape and size, and other morphological characters), a number of cryptic and sibling species have been delineated within different species groups. Notable examples are the ruficornis species group (
The aim of this work is to summarize the knowledge from recent taxonomic and systematic revisions, to help taxonomists to have a central reference for the recent published literature, and to present an identification key for the identification of lineages, species groups, species subgroups and unplaced species of Merodon.
A total of 255 species belonging to the tribe Merodontini (genera Azpeytia Walker, 1865, Eumerus Meigen, 1822, Megatrigon Johnson, 1898, Merodon and Platynochaetus Weidemann, 1830) from the Palaearctic and Afrotropical Regions were studied. All specimens were identified by Ante Vujić and Snežana Radenković. Representative specimens are deposited in the collections of the Department of Biology and Ecology, Faculty of Sciences, University of Novi Sad, Serbia (
Morphological terminology follows
Male genitalia were extracted from dry specimens previously relaxed in a humidity chamber. After genitalia were pulled out with a hook-tipped entomological pin, they were cleared by boiling in warm 10% potassium hydroxide (KOH) for 3–5 min. Acetic acid was then used to neutralize the KOH during 5 s, and genitalia were immersed briefly in ethanol to remove the acid. Prepared genitalia were stored in microvials containing glycerol.
Photographs were taken using a Leica DFC 320 digital camera, attached to a Leica MZ16 stereomicroscope and Nikon Coolpix D7100 digital camera attached to a Nikon SMZ 745T stereomicroscope. Digital photographs were stacked using CombineZ software (
Based on
Merodon Meigen, 1803, Mag. Insektenk, 2, 274. Type-species: Syrphus clavipes Fabricius, 1781, by subsequent designation of Guérin-Méneville in Bory de Saint-Vincent 1826: 446.
Lampetia Meigen, 1800, Nouvelle classification des mouches à deux ailes (Diptera L.) d’après un plan tout nouveau J.J. Fuchs, Paris: 34. Type-species: Syrphus clavipes Fabricius, 1781, by subsequent designation of Coquillett, 1910: 557. Suppressed by
Differential diagnosis. The genus can be distinguished by the presence of an antero-ventral triangular lamina above the apex of the metafemur (as in Suppl. material
As mentioned earlier, there are five monophyletic lineages within the genus Merodon: albifrons, aureus, avidus-nigritarsis, desuturinus, and natans (
In this section and sections below, we provide several identification keys to the 24 species groups, two species subgroups and 10 unplaced species within the genus Merodon. For further species identification inside species groups, species subgroups and species complexes, published revisionary works are cited in brackets.
1 | Mesocoxa without long pile posteriorly (Suppl. material |
avidus-nigritarsis lineage |
– | Mesocoxa with at least a few long pile posteriorly (Suppl. material |
2 |
2 | Mesocoxa with more than 10 long pile posteriorly | 4 |
– | Mesocoxa with a few long pile posteriorly (usually five to seven, or less) (Suppl. material |
3 |
3 | Basoflagellomere elongated, twice as long as wide, narrowed in apical third (Suppl. material |
natans lineage |
– | Basoflagellomere less than half as long as wide, narrowed in apical half (Suppl. material |
desuturinus lineage (in part) |
4 | Anterior anepisternum with bare area ventral to postpronotum (Suppl. material |
6 |
– | Anterior anepisternum with many long pile ventral to postpronotum (Suppl. material |
5 |
5 | Postpronotum usually brown or yellow-reddish. Male genitalia: anterior surstyle lobe with curved distal prolongation (Suppl. material |
desuturinus lineage (in part) |
– | Postpronotum black. Male genitalia: anterior surstyle lobe undeveloped (Suppl. material |
aureus lineage |
6 | Lateral sclerite of the aedeagus gradually tapered, with the tip curved (Suppl. material |
desuturinus lineage (in part) |
– | Lateral sclerite of the aedeagus hammer-like (Suppl. material |
albifrons lineage |
1 | Postpronotum, lateral sides of scutum and face yellowish (Suppl. material |
Merodon luteihumerus Marcos-García, Vujić & Mengual, 2007 |
– | Postpronotum, lateral sides of scutum and face black or dark | 2 |
2 | Pro- and mesolegs strongly modified (Suppl. material |
Merodon mixtum Vujić, Radenković & Likov, 2019 |
– | Pro- and mesolegs with usual shape | 3 |
3 | Pilosity on the posterior part of abdomen (at least tergum 4) denser and strikingly golden to reddish-yellow (as in Suppl. material |
constans species group ( |
– | Pilosity on the posterior part of abdomen not denser compared to the anterior part (Suppl. material |
4 |
4 | Large (11–17 mm) bumble bee-like species with dense and long body pilosity (Suppl. material |
equestris species group ( |
– | Species with different characters | 5 |
5 | Medium to large sized species (9–13 mm) with black, bronze lustre terga (lack pollinose fasciate maculae), except a pair of small, orange, lateral markings on tergum 2 (Suppl. material |
rufus species group ( |
– | Species with different characters; usually with pollinose fasciate maculae on terga | 6 |
6 | Female (genitalia not visible) | 9 |
– | Male (genitalia visible externally) | 7 |
7 | Metaleg with some modifications on metatrochanter, metafemur and/or metatibia; male genitalia often with hook-like posterior surstyle lobe or cercus with prominence(s) | 8 |
– | Metaleg usually without modifications (exception is Merodon trochantericus Costa, 1884, see in Suppl. material |
albifrons species group |
8 | Metatrochanter with blunt calcar apically covered with long pile (Suppl. material |
geniculatus species group ( |
– | Metatrochanter with sharp apical calcar (Suppl. material |
ruficornis species group ( |
9 | Metatibia narrow, not swollen apically (Suppl. material |
ruficornis species group ( |
– | Metatibia incrassate apically (Suppl. material |
10 |
10 | Scutum usually with five distinct pollinose vittae (Suppl. material |
geniculatus species group ( |
– | Scutum with indistinct pollinose vittae; terga 2–4 without or with narrower pollinose fasciate maculae (Suppl. material |
albifrons species group |
1 | Female (genitalia not visible) | 6 |
– | Male (genitalia visible externally) | 2 |
2 | Metatrochanter with calcar (Suppl. material |
5 |
– | Metatrochanter rounded and smooth, without calcar (Suppl. material |
3 |
3 | Hypandrium strongly modified, sinuous in apical half, with subapical ctenidium and stitched theca (cuticle looks like it is sewed) (Suppl. material |
spinitarsis species group |
– | Hypandrium different, but with apical ctenidium and without stitch on theca (as in Suppl. material |
4 |
4 | Pedicel elongated, approximately as long as basoflagellomere (relation pedicel basoflagellomere = 0.9 : 1.1) (Suppl. material |
bombiformis species group (Afrotropical Region) |
– | Pedicel shorter than basoflagellomere (as in Suppl. material |
nanus species group ( |
5 | Yellow-grey pilosity on terga more dense and striking laterally, as well as on pollinose fasciate maculae of terga 2 and 3, and on tergum 4 (Suppl. material |
funestus species group |
– | Terga evenly covered with upstanding, dense pilosity (can be differently coloured) (Suppl. material |
aureus species group ( |
6 | Pedicel shorter than basoflagellomere (Suppl. material |
8 |
– | Pedicel elongated, approximately as long as basoflagellomere (relation pedicel : basoflagellomere = 0.9 : 1.1) (Suppl. material |
7 |
7 | Apical triangular lamina on metafemur weakly serrated, usually with distinct apical dens (Suppl. material |
bombiformis species group (Afrotropical Region) |
– | Apical triangular lamina on metafemur markedly serrated (Suppl. material |
funestus species group |
8 | Terga without pollinose fasciate maculae, with dense puncta (Suppl. material |
9 |
– | Terga 2–4 (at least 2) usually with pollinose medial fasciate maculae, with less dense puncta (Suppl. material |
aureus species group ( |
9 | Tergum 4 covered with short adpressed pile (Suppl. material |
spinitarsis species group |
– | Tergum 4 covered with longer semi-erect pile, longer than basoflegellomere (Suppl. material |
nanus species group ( |
1 | Inner side of metafemur with a row of spinae (Suppl. material |
Merodon eumerusi Vujić, Radenković & Likov, 2019 |
– | Inner side of metafemur without a row of spinae | 2 |
2 | Terga partly brown, reddish or yellow | 22 |
– | Terga black | 3 |
3 | Females (genitalia not visible) | 13 |
– | Males (genitalia visible externally) | 4 |
4 | Male genitalia without ctenidium at hypandrium (Suppl. material |
fulcratus species group |
– | Male genitalia always with ctenidium at hypandrium (as in Suppl. material |
5 |
5 | Large species (15–20 mm) with long body pilosity and broad metafemur covered with long pile (Suppl. material |
clavipes species group |
– | Species with shorter pilosity and different combinations of characters | 6 |
6 | Sternum 4 medially clearly divided with membranous structure and with posterolateral tubercles or laminate extensions (Suppl. material |
tarsatus species group |
– | Sternum 4 and basotarsomere of metatarsus without such modifications | 7 |
7 | Male genitalia: posterior surstyle lobe divided into two branches (Suppl. material |
Merodon hirtus Sack, 1932 |
– | Male genitalia: posterior surstyle lobe not divided into branches; eyes holoptic | 8 |
8 | Abdomen elongated and narrow; terga black; terga 2–4 with a pair of pollinose fasciate maculae (Suppl. material |
aberrans species group |
– | Species with different combinations of characters | 9 |
9 | Basoflagellomere elongated, at least three times as long as wide (Suppl. material |
italicus species group (in part) |
– | Basoflagellomere less elongated; posterior surstyle lobe different | 10 |
10 | Posterior surstyle lobe with basolateral protrusion (lateral hump) (Suppl. material |
serrulatus species group (in part) ( |
– | Posterior surstyle lobe of male genitalia without basolateral protrusion (lateral hump) | 11 |
11 | Basoflagellomere reddish-yellow (Suppl. material |
Merodon ottomanus Hurkmans, 1993 |
– | Basoflagellomere brown to black; tarsi of metaleg dark; metatarsus shorter, two times longer than wide (Suppl. material |
12 |
12 | Basoflagellomere with convex dorsal margin (Suppl. material |
Merodon clunipes Sack, 1913 (in part) |
– | Basoflagellomere with concave dorsal margin (Suppl. material |
Merodon auronitens Hurkmans, 1993 |
13 | Metafemur more incrassate, ca. three times longer than wide, covered with dense pilosity (Suppl. material |
14 |
– | Metafemur less incrassate, at least three times longer than wide (as in Suppl. material |
15 |
14 | Basoflagellomere shorter, 1.3 times as long as wide, with convex dorsal margin (Suppl. material |
Merodon clunipes Sack, 1913 (in part) |
– | Basoflagellomere elongated, two times as long as wide (Suppl. material |
clavipes species group (in part) |
15 | Small sized species (8-11 mm) with metallic shiny body; scutum and terga strongly punctate, without or with very weak pollinose areas (Suppl. material |
fulcratus group |
– | Species with different combinations of characters | 16 |
16 | Metafemur with short pilosity (Suppl. material |
serrulatus species group (in part) ( |
– | Metafemur with longer pile (as in Suppl. material |
17 |
17 | Abdomen broad, oval (Suppl. material |
Merodon ottomanus Hurkmans, 1993 |
– | Species with different combinations of characters | 18 |
18 | Basotarsomere of metatarsus elongated, four times as long as wide (Suppl. material |
Merodon murinus Sack, 1913 (in part) |
– | Species with different combinations of characters | 19 |
19 | Abdomen narrow, elongated (Suppl. material |
aberrans species group |
– | Species with broader abdomen and metaleg | 20 |
20 | Tergum 2 without or with indistinct narrow pollinose fasciate maculae (Suppl. material |
tarsatus species group |
– | Tergum 2 with broad pollinose fasciate maculae (Suppl. material |
21 |
21 | Terga 2–4 strongly punctate; second and third tarsomeres similar in size (Suppl. material |
Merodon auronitens Hurkmans, 1993 |
– | Terga 2–4 finely punctate; second tarsomere longer than third (Suppl. material |
Merodon hirtus Sack, 1932 |
22 | Females (genitalia not visible) | 31 |
– | Males (genitalia visible externally) | 23 |
23 | Metatibia swollen in apical half (Suppl. material |
Merodon caudatus Sack, 1913 |
– | Metaleg without such modifications | 24 |
24 | Posterior surstyle lobe with basolateral protrusion (lateral hump) (Suppl. material |
serrulatus species group (in part) ( |
– | Posterior surstyle lobe without basolateral protrusion | 25 |
25 | Face with a bulge below antennae (Suppl. material |
Merodon crassifemoris Paramonov, 1925 |
– | Face without a bulge below antennae | 26 |
26 | Metatrochanter without calcar | 28 |
– | Metatrochanter with distinct calcar (Suppl. material |
27 |
27 | Basoflagellomere 1.2 times as long as wide (Suppl. material |
aurifer species group |
– | Basoflagellomere short, as long as wide (Suppl. material |
pruni species group |
28 | Basoflagellomere elongated, at least three times as long as wide (Suppl. material |
italicus species group (in part) |
– | Basoflagellomere shorter, less than three times as long as wide (as in Suppl. material |
29 |
29 | Eye contiguity very short, approximately four to five facets long (Suppl. material |
Merodon murinus Sack, 1913 (in part) |
– | Eye contiguity more than 10 facets long (as in Suppl. material |
30 |
30 | Tarsi yellow dorsally and ventrally (Suppl. material |
avidus species group ( |
– | Tarsi dark brown/black dorsally and orange/brown ventrally (Suppl. material |
nigritarsis species group ( |
31 | At least terga 2 and 3 with brown, reddish or yellow markings | 36 |
– | Only tergum 2 with brown, reddish or yellow maculae, other terga dark | 32 |
32 | Metatibia swollen in apical half (Suppl. material |
Merodon caudatus Sack, 1913 |
– | Metatibia of normal shape (as in Suppl. material |
33 |
33 | Pile on ventral margin of metafemur dense and long, the longest as long as width of metafemur (Suppl. material |
clavipes species group |
– | Pile on ventral margin of metafemur shorter, maximum as long as half of width of metafemur (as in Suppl. material |
34 |
34 | Basoflagellomere shorter, 1.3 times as long as wide, with convex dorsal margin (Suppl. material |
Merodon clunipes Sack, 1913 (in part) |
– | Basoflagellomere longer, with straight or concave dorsal margin (Suppl. material |
35 |
35 | Tarsi yellow, tibiae mostly yellowish, only medially brown; frons and vertex usually partly reddish to yellow (Suppl. material |
Merodon murinus Sack, 1913 (in part) |
– | Legs mostly black, at least tarsi dark; frons black |
serrulatus species group (in part) ( |
36 | Basoflagellomere elongated, more than 1.5 times as long as wide (Suppl. material |
38 |
– | Basoflagellomere shorter, less than 1.3 times as long as wide (Suppl. material |
37 |
37 | Basoflagellomere very short, as long as wide (Suppl. material |
pruni species group |
– | Basoflagellomere longer, 1.2 times as long as wide (Suppl. material |
aurifer species group |
38 | Face with a bulge below antennae (Suppl. material |
Merodon crassifemoris Paramonov, 1925 |
– | Face without a bulge below antennae | 39 |
39 | Basoflagellomere elongated, at least 2.7 times as long as wide (Suppl. material |
italicus species group (in part) |
– | Basoflagellomere shorter, less than 2.5 times as long as wide (as in Suppl. material |
40 |
40 | Tarsi yellow dorsally and ventrally (as in Suppl. material |
avidus species group ( |
– | Tarsi dark brown/black dorsally and orange/brown ventrally (as in Suppl. material |
nigritarsis species group ( |
1 | Oral margin reduced, covered by microtrichia (Suppl. material |
planifacies species subgroup ( |
– | Oral margin notched, slightly produced forward (as in Suppl. material |
2 |
2 | Metatrochanter with sparse pale pile (Suppl. material |
3 |
– | Metatrochanter with dense and strong yellow to red brush of pile (Suppl. material |
melanocerus species subgroup ( |
3 | Apical fourth of tibiae and all tarsi bright yellow; Afrotropical species (Zimbabwe) | Merodon cuthbertsoni Curran, 1939 |
– | Tarsi partly brown or black; Palaearctic species |
murorum species group ( |
1 | Scutum with distinct pollinose ornamentation, vittae and fasciae (Suppl. material |
natans species group |
– | Scutum with indistinct pollinose vittae (Suppl. material |
Merodon segetum Fabricius, 1794 |
Diagnosis. From small to large sized species (7–19 mm) with non-tapering abdomen and a characteristic structure of male genitalia. It is defined by having the mesocoxa pilose posteriorly (> 10 pile) (Suppl. material
The albifrons lineage comprises 65 species (61 described + 4 undescribed) distributed in six species groups (albifrons, constans, equestris, geniculatus, ruficornis, and rufus) and two unplaced species: M. luteihumerus Marcos-García, Vujić & Mengual, 2007 and M. mixtum Vujić, Radenković & Likov, 2019 (Suppl. material
Diagnosis. Small to medium-sized species (7–11 mm); abdominal terga at least partly reddish; terga 2–4 usually each with a pair of pollinose fasciate maculae; male metaleg without projections, calcars or spina, except M. trochantericus Costa, 1884 on metatrochanter, metafemur and apex of metatibia (Suppl. material
Diversity and distribution. The albifrons species group contains eight described species (Suppl. material
Identification. An identification key to the species of this group is in preparation (Vujić, unpublished).
Diagnosis. Medium to large-sized species (9–18 mm); posterior part of abdomen (at least tergum 4) covered with golden to reddish-yellow pile (as in Suppl. material
Diversity and distribution. Predominantly northern and eastern Mediterranean distribution, with no representatives on the Iberian Peninsula (
Identification.
Diagnosis. Medium to large-sized species (11–17 mm) characterised by bumble bee mimicry, with long body pile (Suppl. material
Diversity and distribution. Three species belong to the equestris species group: M. confusus Marcos-García, Vujić, Ricarte & Ståhls, 2011, M. equestris and M. flavus Sack, 1913, all native to South Europe. Merodon equestris has been introduced elsewhere, including Japan, North America and New Zealand (
Identification.
Diagnosis. Tergum 2 with reddish lateral maculae; terga 2–4 with distinct pollinose fasciate maculae (Suppl. material
Diversity and distribution. The geniculatus species group comprises 11 described species.
Identification. A taxonomic revision of the Eastern Mediterranean species is provided by
Diagnosis. Metatrochanter, metafemur and metatibia usually with tubercle, calcar or lamina in the male (Suppl. material
Diversity and distribution. A total of 18 species are recognized in the ruficornis species group (
Identification. Distributional data and an identification key for 18 species are provided by
Diagnosis. In general appearance similar to the members of the ruficornis species group. This group comprises black species with bronze reflections that are covered with golden-yellow erect pile, shiny terga and sterna without any trace of pollinosity, and tergum 2 with a pair of small lateral orange maculae (Suppl. material
Diversity and distribution. The European rufus species group is composed of four species, three of which belong to recently described species from Mediterranean mountains, namely M. kozufensis Radenković & Vujić, 2020, M. olympius Vujić & Radenković, 2020, and M. orjensis Radenković & Vujić, 2020 (
Identification.
Merodon luteihumerus (Suppl. material
Merodon mixtum (Suppl. material
Diagnosis. Posterior part of the mesocoxa pilose (as in Suppl. material
The aureus lineage contains five species groups: aureus, bombiformis, funestus, nanus, and spinitarsis with 61 species, 48 of which are described and 13 undescribed (Suppl. material
Diagnosis. Small to medium sized species (8–12 mm) with a short rounded abdomen, a distinct calcar on the metatrochanter in males. Male genitalia have a characteristic posterior surstyle lobe with parallel margins and rounded apex (as in Suppl. material
Diversity and distribution. The aureus species group comprises a large number of previously known and recently discovered taxa distributed mostly in the Mediterranean Region and South Europe with a high number of local endemics.
Identification. The identification keys for the various species subgroups have already been published: aureus species subgroup (
Diagnosis. Elongated pedicel, approximately as long as basoflagellomere (relation pedicel: basoflagellomere = 0.9 : 1.1) (Suppl. material
Diversity and distribution. The bombiformis species group consists of six related, though clearly morphologically different species distributed in central and southern Africa, of which three have been described (M. bombiformis Hull, 1944, M. multifasciatus Curran, 1939, and M. nasicus Bezzi, 1915) and three remain undescribed (Suppl. material
Identification. A taxonomic revision of this species group is in preparation (Vujić, unpublished).
Diagnosis. The funestus and the bombiformis species groups differ from other species and species groups of the aureus lineage by the elongated pedicel, approximately as long, or even longer, than basoflagellomere (Suppl. material
Diversity and distribution. The funestus species group (Suppl. material
Identification. A taxonomic revision is currently being prepared (Vujić, unpublished).
Diagnosis. Small to medium-sized species (6–12 mm) with a short rounded abdomen. Differs from the members of the aureus species group by the absence of a calcar on the metatrochanter in males and abdominal terga with transverse fasciae of pale pile instead of pollinose fasciate maculae (rarely with indistinct pollinosity). Male genitalia with a broad hypandrium (as in Suppl. material
Diversity and distribution. We recognized six taxa within the nanus species group (Suppl. material
Identification.
Diagnosis. Members of this species group resemble in their overall appearance species of the nanus species group, from which they can be easily distinguished by black tibiae and tarsi (mostly pale in the nanus species group), and the structure of the male genitalia: hypandrium of male genitalia strongly modified, anfractuous in apical half, with subapical ctenidium and stitched theca (Suppl. material
Diversity and distribution. Only two species are known, M. spinitarsis Paramonov, 1929, and an undescribed species (Suppl. material
Identification. A taxonomic revision is currently being prepared (Vujić, unpublished).
Diagnosis. Medium to large-sized species (11–20 mm) usually with white pollinose vittae on scutum (Suppl. material
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: M. auronitens Hurkmans, 1993, M. caudatus Sack, 1913, M. clunipes Sack, 1913, M. crassifemoris Paramonov, 1925, M. eumerusi, M. hirtus Sack, 1932, M. murinus Sack, 1913 and M. ottomanus Hurkmans, 1993. This lineage comprises 79 species, 66 of which are described and 13 undescribed (Suppl. material
Diagnosis. Abdomen elongated and narrow with black shiny terga; terga 2–4 with a pair of white pollinose fasciate maculae (Suppl. material
Diversity and distribution. This species group consists of four described species: (Merodon aberrans Egger, 1860, Merodon brevis
Identification. A taxonomic revision including an identification key and descriptions for the four new species is in preparation (Vujić, unpublished).
Diagnosis. Species with short body pilosity, basoflagellomere 1.2 times as long as wide (Suppl. material
Diversity and distribution. Besides M. aurifer Loew, 1862 distributed in the north Mediterranean and Turkey, the species group consists of at least one additional taxon, an undescribed species from Turkey and Azerbaijan.
Identification. A nomenclatural revision of the species group and the description of the new species is in preparation (Vujić, unpublished).
Diagnosis. Species with elongated and tapering abdomen (Suppl. material
Diversity and distribution. The avidus species group is composed of the avidus species complex with four species, and the species M. femoratus Sack, 1913 and M. rutitarsis Likov, Vujić & Radenković, 2020 (Suppl. material
Identification. A taxonomic revision with an identification key are presented in
Diagnosis. Large bumble bee-like species (15–20 mm) with long body pilosity and broad metafemur with long pile (Suppl. material
Diversity and distribution. The clavipes species group contains four species (Suppl. material
Identification. A taxonomic revision of this species group is under preparation (Vujić, unpublished).
Diagnosis. They are small sized species (5–9 mm) with metallic shiny bodies; scutum and terga strongly punctate, without or with very weak pollinose areas (Suppl. material
Diversity and distribution. Two species are known, M. dichopticus Stackelberg, 1968 from Turkey and M. fulcratus (Becker, 1913) from Iran.
Identification. A taxonomic revision of this group is under preparation (Vujić, unpublished).
Diagnosis. Species with elongate basoflagellomere, at least 2.7 times as long as wide (Suppl. material
Diversity and distribution. Two species share these morphological features and belong to this species group: M. italicus Rondani, 1845 recorded from most of the Mediterranean and M. erivanicus Paramonov, 1925 distributed from Croatia to Azerbaijan and Israel.
Identification. A taxonomic revision of this group is in preparation (Vujić, unpublished).
Diagnosis. Species with elongate, narrow and tapering abdomen, tarsi dark brown/black dorsally and partly orange ventrally. Male genitalia: anterior surstyle lobe more or less rhomboid shape (Suppl. material
Diversity and distribution. The nigritarsis species group includes 17 species revised in
Identification. A taxonomic revision is provided by
Diagnosis. Medium to large-sized species (10–18 mm) characterised by short body pilosity (scutum and abdomen); short basoflagellomere, as long as broad (Suppl. material
Diversity and distribution. Four species belong to this species group: M. cupreus Hurkmans, 1993, M. pallidus Macquart, 1842 and M. pruni Rossi, 1790 and one undescribed taxon from Israel. Merodon pruni is distributed in most of the Mediterranean Basin, but the other two described species are more allocated to the east, from Turkey to Israel and Pakistan.
Identification. A taxonomic revision of this group is in preparation (Vujić, unpublished).
Diagnosis. Species with characteristic basolateral protrusion on the posterior surstyle lobe at outer surface (Suppl. material
Diversity and distribution. This species group includes 13 species (
Identification. This species group is revised by
Diagnosis. Small to medium sized species (8–14 mm) with usually expanded basotarsomere of metatarsus (Suppl. material
Diversity and distribution. The tarsatus species group consists of seven described and six undescribed species (Suppl. material
Identification.
Merodon auronitens (Suppl. material
Merodon caudatus (Suppl. material
Merodon clunipes (Suppl. material
Merodon crassifemoris (Suppl. material
Merodon eumerusi (Suppl. material
Merodon hirtus (Suppl. material
Merodon murinus (Suppl. material
Merodon ottomanus (Suppl. material
Diagnosis. The specific shape of the lateral sclerite of the aedeagus (gradually tapered, with the tip curved downwards) is the main synapomorphic character that connects all species from the group (as in Suppl. material
The desuturinus lineage contains the Afrotropical melanocerus species group with two species subgroups (melanocerus and planifacies) and the species M. cuthbertsoni Curran, 1939 (
Diagnosis. Species with patch of dense yellow pile (dense and strong yellow to red brush of pile) on metatrochanter (Suppl. material
Diversity and distribution. Distribution of the melanocerus species subgroup is limited to South Africa, while the planifacies species subgroup has broader range: western, central and southern Africa. Merodon cuthbertsoni occurs in Zimbabwe.
Identification. Recent revision of the melanocerus species subgroup (
Diagnosis. Species without patch of dense yellow pile (dense and strong yellow to red brush of pile) on metatrochanter.
Diversity and distribution. This species group includes four endemo-relicts: M. cabanerensis Marcos-García, Vujić & Mengual, 2007, known only from a restricted area in central Spain and Morocco; M. desuturinus Vujić, Šimić & Radenković, 1995 (Suppl. material
Identification.
Diagnosis. Species with few pile on posterior side of mesocoxa; pile on anterior anepisternum reduced; anterior lobe of surstylus well developed, oval, rounded, pilose, without curved distal prolongation (Suppl. material
The natans lineage contains the natans species group with three described species (
Diagnosis. Small to medium-sized species (8–13 mm) with distinct pollinose ornamentation, vittae and fasciae, on scutum (Suppl. material
Diversity and distribution. The natans species group is distributed around the Mediterranean Basin and there is one isolated record in Kenya (Vujić, unpublished).
Identification. A taxonomic revision of this species group is in preparation (Vujić, unpublished).
Merodon segetum is a large species (14–17 mm) (Suppl. material
Out of 194 described species (234 in total including undescribed taxa), 180 (209) species are distributed in the Palaearctic Region and 14 (27) are known from the Afrotropical Region. Three lineages (aureus, desuturinus, and natans) have representatives in both the Afrotropical and the Palaearctic Regions. The Afrotropical melanocerus species group of the desuturinus lineage and the bombiformis species group of the aureus lineage are exclusive to the Afrotropical Region, while all other species groups belong to Palaearctic fauna.
The albifrons lineage, with 65 species (61 described taxa), contains six species groups (albifrons, constans, equestris, geniculatus, ruficornis, and rufus) and two unplaced taxa.
The aureus lineage, with 61 species (48 described), contains five species groups (aureus, bombiformis, funestus, nanus, and spinitarsis).
The avidus-nigritarsis lineage, with 79 species (67 described), is divided into 10 species groups (aberrans, aurifer, avidus, clavipes, fulcratus, italicus, nigritarsis, pruni, serrulatus, and tarsatus) and eight unplaced species.
The desuturinus lineage, with 24 species (14 described), contains two species groups: the Afrotropical melanocerus species group with two species subgroups (melanocerus and planifacies) and the unplaced species M. cuthbertsoni; and the Palaearctic murorum species group with four species.
The natans lineage contains the natans species group, with four species (three described), and the unplaced species M. segetum.
At present and based on our results, the regions with the highest species richness are the Mediterranean Peninsulas: Iberian, Balkan and especially Anatolian. Certain areas in the Palaearctic (regions of Pakistan, Central Asia and eastern part of the Middle East) and Afrotropical Regions (Central and Eastern Africa) have been under-sampled and they need additional collecting efforts. Central Asia and Pakistan are characterised by numerous endemics with potential significance to understand the evolutionary scenario of the genus Merodon. Finally, the genetic diversity is extremely high in the aureus species group and more taxonomic research still needs to be done in this species group and some others, like the ruficornis, avidus and equestris species groups.
We thank Branka Božičić Lothrop for valuable comments and editing of the manuscript, and Hugh Lothrop, native English speaker, for linguistic revision. The study was supported by the Ministry of Education, Science and Technological Development, Republic of Serbia, Grant No. 173002, III43002, 451–03–68/2020–14/200358 and 451–03– 68/2020–14/200125, the Provincial Secretariat for Science and Technological Development of the Republic of Serbia (Grant No. 114–451–1125/2014–03 and 114–451–1702/2014–03).
Figures S1–S37: Figures of morphological characters
Data type: multimedia
Explanation note: Figure S1. Head of male, posterior view. A Platynochaetus setosus (Fabricius, 1794), hypostomal bridge marked with arrow B Sericomyia silentis (Harris, 1776). Scale bar: 0.5 mm. Figure S2. Parts of thorax of male, lateral view. A Merodon megavidus Vujić & Radenković, 2016, tubercle B Eristalinus megacephalus (Rossi, 1794), tubercle C Merodon megavidus, anepimeron D Sericomyia silentis, anepimeron. A, B tubercle marked with arrow C, D dorsomedian part of anepimeron marked with arrow. Scale bar: 0.5 (A–C); 1 mm (D). Figure S3. A, B Wing of male, dorsal view C–D Antenna of male, lateral view. A Merodon aff. nasicus, short vein marked with asterisk B Sericomyia silentis C Merodon ottomanus, fossette marked with arrow D Microdon analis (Macquart, 1842). A, B outer angle between R4+5 and M1 marked with arrow. Scale bar: 0.5 mm (A, B, D); 0.2 mm (C). Figure S4. Metacoxa of male. A Merodon albifrons Meigen, 1822, lateral view B M. nigritarsis Rondani, 1845, lateral view. A, B pile marked with arrow. Scale bar: 0.25 mm. Figure S5. A Metafemur of Merodon eumerusi, male, lateroventral view, row of spinae marked with arrow B Mesocoxa of M. segetum, male, lateral view, pile marked with arrow. Scale bar: 1 mm. Figure S6. A, B Antenna of male, lateral view C, D Thorax of male, dorsal view. A, C Merodon natans (Fabricius, 1794) B, D M. desuturinus. Scale bar: 1 mm. Figure S7. Thorax (anepisternum) of male, lateral view. A Merodon geniculatus B M. legionensis Marcos-García, Vujić & Mengual, 2007. A, B pile marked with arrow. Figure S8. Abdomen of female, lateral view. A Merodon desuturinus B M. aureus Fabricius, 1805. A, pile marked with arrow. Scale bar: 1 mm. Figure S9. Part of wing of male, dorsal view. A Merodon desuturinus B M. albifrons. A–B microtrichia marked with arrow. Scale bar: 1 mm. Figure S10. Antenna of Merodon eumerusi, male, lateral view. A outer side B inner side. Scale bar: 1 mm. Figure S11. A, B Eye contiguity of male, anterior view C, D Sternum 4 of male, dorsal (C) and lateral (D) view E Abdomen of male, dorsal view. A Merodon fulcratus B M. hirtus C, D M. tarsatus E M. aberrans. C, D membranous structure and laminate extension marked with arrow. Scale bar: 1 mm (A, B); 2 mm (C–E). Figure S12. Parts of male metaleg, lateral view. A Merodon fulcratus, metaleg B M. clavipes (Fabricius, 1781), metafemur and metatibia C M. tarsatus, metatarsus D M. oidipous Hurkmans, 1993, metatarsus. C, D setae marked with arrrow. Scale bar: 2 mm (A, B); 0.5 mm (C, D). Figure S13. Male antenna, lateral view. A Merodon italicus B M. serrulatus C M. ottomanus D M. clunipes E M. auronitens. Scale bar: 2 mm. Figure S14. Parts of male metaleg, lateral view. A Merodon serrulatus, metafemur and metatibia B M. ottomanus, metaleg C M. clunipes, metafemur D M. clunipes, metatarsus. Scale bar: 2 mm. Figure S15. Parts of female metaleg, lateral view. A Merodon clunipes, metafemur and metatibia B M. ottomanus, metaleg C M. clavipes, metafemur D M. fulcratus, metafemur E M. serrulatus, metafemur F M. murinus, metatibia and metatarsus. Dtriangular lamina marked with arrow. Scale bar: 2 mm. Figure S16. Female antenna, lateral view. A Merodon clunipes B M. clavipes C M. murinus. Scale bar: 2 mm. Figure S17. A Female thorax, dorsal view B–D Abdomen of female, dorsal view. A, B Merodon fulcratus C M. ottomanus D M. aberrans. Scale bar: 2 mm. Figure S18. Parts of female metaleg, lateral view. A Merodon aberrans, metaleg B M. tarsatus, metatarsus C M. hirtus, metatarsus D M. auronitens, metatarsus. B setae marked with arrow C-D tarsomerae marked with arrow. Scale bar: 1 mm (A); 2 mm (B–D). Figure S19. Abdomen of female. A Merodon oidipous, dorsal view B M. tarsatus, dorsal view C M. auronitens, dorsal view D M. auronitens, lateral view E M. hirtus, lateral view. Scale bar: 2 mm. Figure S20. Parts of male metaleg. A Merodon caudatus, metatibia and metatarsus, lateral view B M. aurifer, metatrochanter and metafemur, lateral view C M. avidus (Rossi, 1790), metatarsus, dorsal view D M. avidus, metatarsus, ventral view E M. nigritarsis, metatarsus, dorsal view F M. nigritarsis, metatarsus, ventral view G M. pruni, part of metafemur, lateral view H M. pruni, metatrochanter, lateral view. B calcar marked with arrow. Scale bar: 0.5 mm (A–B); 1mm (C–G); 0.25 mm (H). Figure S21. A Merodon crassifemoris, male, head, lateral view B M. murinus, male, eye contiguity, anterior view C M. nigritarsis, male, eye contiguity, anterior view. A bulge marked with arrow. Scale bar: 1 mm. Figure S22. Abdomen, dorsal view. A Merodon aurifer B M. pruni C M. avidus D M. serrulatus. A–C male D female. Scale bar: 2 mm. Figure S23. Male antenna, lateral view. A Merodon aurifer B M. pruni C M. nigritarsis. Scale bar: 1 mm (A, C); 0.5 mm (B). Figure S24. Parts of metaleg of female. A Merodon caudatus, metafemur and metatibia, lateral view B M. caudatus, metatarsus, dorsal view C M. pruni, metatrochanter, metafemur and metatibia D M. crassifemoris, metatrochanter, lateral view E M. aurifer, metafemur and metatibia. C metatrochanter marked with arrow. Scale bar: 1 mm (A, C, E); 0.5 mm (B); 0.75 mm (D). Figure S25. A Merodon murinus, female, head, dorsal view B M. crassifemoris, female, head, dorsolateral view C M. italicus, female, abdomen, dorsal view. B bulge marked with arrow. Scale bar: 1 mm (A–B); 2 mm (C). Figure S26. Antenna of female, lateral view. A Merodon pruni B M. crassifemoris C M. aurifer D M. italicus E M. avidus. Scale bar: 0.5 mm (A–C, E); 1 mm (D). Figure S27. A Merodon natans, male, abdomen, dorsal view B M. segetum, male, abdomen, dorsal view C M. natans, male, antenna, lateral view D M. natans, male, thorax, dorsal view E M. segetum, male, thorax, dorsal view. Scale bar: 2 mm (A–C); 1 mm (D); 0.5 mm (E). Figure S28. Parts of metaleg. A Merodon bombiformis, male, metatrochanter, lateral view B M. aureus, male, metatrochanter, lateral view C M. spinitarsis, female, metatarsus, dorsal view D M. nanus (Sack, 1931), female, metatarsus, dorsal view E M. bombiformis, female, metafemur, lateral view F M. funestus, female, metafemur, lateral view G M. funestus, male, metafemur and metatrochanter, lateral view H M. bombiformis, male, metafemur and metatrochanter, lateral view. B calcar on the metatrochanter marked with arrow E triangular lamina marked with arrow. Scale bar: 2 mm. Figure S29. Antenna, lateral view. A Merodon bombiformis, male B M. nanus, male C M. funestus, male D M. aureus, male E M. funestus, female F M. aureus, female. Scale bar: 2 mm. Figure S30. Abdomen. A Merodon funestus, male, dorsolateral view B M. aureus, male, lateral view C M. nanus, female, dorsal view D M. aureus, female, dorsal view E M. spinitarsis, female, lateral view F M. nanus, female, lateral view. Scale bar: 2 mm. Figure S31. Merodon luteihumerus, male. A head, anterior view B thorax, dorsolateral view. Scale bar: 2 mm. Figure S32. Merodon mixtum, legs, lateral view. A proleg, male B proleg, female C mesoleg, male D mesoleg, female E metaleg, male F metaleg, female. Scale bar: 1 mm. Figure S33. A–C Abdomen of male D Metatibia. A Merodon gudaurensis Portschinsky, 1877, dorsal view B M. rufus, dorsal view C M. rufus, lateral view D M. albifrons, lateral view. Scale bar: 2 mm. Figure S34. Parts of metaleg, lateral view. A Merodon equestris, male, metatibia B M. rufus, male, metaleg C M. trochantericus, male, metaleg D M. albifasciatus, male, metatrochanter E M. albifasciatus, male, metatibia F M. trebevicensis Strobl, 1900, male, metatrochanter, metafemur and metatibia G M. ruficornis Meigen, 1822, female, metatibia H M. albifasciatus, female, metatibia I M. gudaurensis, male, metafemur J M. gudaurensis, male, metatibia. E apicomedial carina marked with arrow F ventral tubercle on metafemur and apicolateral process on metatibia marked with arrow. Scale bar: 0.5 mm (A, B); 2 mm (C); 1 mm (D–E); 2 mm (F); 2 mm (G–H); 2 mm (I-J). Figure S35. A Merodon albifasciatus, female, thorax, dorsal view B M. albifasciatus, female, abdomen, dorsal view C M. albifrons, female, abdomen, dorsal view. Scale bar: 2 mm. Figure S36. A, B Head of female, dorsal view C, D Tip of abdomen, dorsal view. A Merodon ruficornis B M. rufus C M. ruficornis, female D M. mixtum, male. B pollinosity along eye margin marked with arrow C transversal depression on tergum 4 and lateral depressions on tergum 5 marked with arrow. Scale bar: 2 mm. Figure S37. A–B Head of male, lateral view C–D Metatrochanter of male, lateral view. A Merodon planifacies B M. neolydicus C M. desuturinus D M. draconis Vujić & Radenković, 2018. Scale bar: 1 mm (A–B); 2 mm (C–D).
Figures S1–S13: Figures of male genitalia
Data type: multimedia
Explanation note: Figure S1. Male genitalia. A–C Merodon constans (Rossi, 1794) D–F M. chrysotrichos Vujić, Radenković & Likov, 2020 G–I M. triangulum Vujić, Radenković & Hurkmans, 2020. A, B, D–E, G, H epandrium C, F, I hypandrium. A, C, D, F, G, I lateral view B, E, H ventral view. Abbreviations: c-cercus, s-lateral sclerite of the aedeagus. Scale bar: 0.5 mm. Figure S2. Male genitalia. A–C Merodon albifrons Meigen, 1822 D–F M. equestris G–I M. albifasciatus. A–B, D–E, G–H epandrium C, F, I hypandrium. A, C, D, F, G, I lateral view B, E, H ventral view. Abbreviations: al-anterior surstyle lobe, c-cercus, s-lateral sclerite of the aedeagus. Scale bar: 0.4 mm (A–C); 0.2 mm (D–F); 0.4 mm (G–I). Figure S3. Male genitalia. A–C Merodon ruficornis Meigen, 1822 D–F M. rufus G–I M. luteihumerus J–L M. mixtum. A–B, D–E, G–H, J–K epandrium C, F, I, L hypandrium. A, C, D, F, G, I, J, L lateral view B, E, H, K ventral view. Abbreviations: c-cercus, s-lateral sclerite of the aedeagus. Scale bar: 0.4 mm (A–C); 0.25 mm (D–F); 0.2 mm (G–I); 0.5 mm (J–L). Figure S4. Male genitalia. A–D Merodon aureus Fabricius, 1805 E–H M. nanus (Sack, 1931) I–K M. spinitarsis. A, B, E, F, I, J epandrium C, G, K hypandrium D, H part of aedeagus. A, C, D, E, G, I, K lateral view B, F, H, J ventral view. Abbreviations: al-anterior surstyle lobe, pl-posterior surstyle lobe. D place of lateral sclerite of the aedeagus marked with arrow. Scale bar: 0.25 mm (A–D); 0.25 mm (E–H); 0.5 mm (I–K). Figure S5. Male genitalia. A–C Merodon bombiformis D–F M. nasicus G–I M. funestus. A–B, D–E, G–H epandrium C, F, I hypandrium. A, C, D, F, G, I lateral view B, E, H ventral view. Abbreviations: pl-posterior surstyle lobe, s-lateral sclerite of the aedeagus. C, F medially narrowed hypandrium marked with arrow. Scale bar: 0.5 mm. Figure S6. Male genitalia. A–C Merodon aberrans D–F M. aurifer G–I M. avidus (Rossi, 1790) J–L M. rutitarsis. A–B, D–E, G–H, J–K epandrium C, F, I, L hypandrium. A, C, D, F, G, I, J, L lateral view B, E, H, K ventral view. Abbreviations: l-lingula. Scale bar: 0.2 mm (A–C, G–I); 0.5 mm (D–F, J–L). Figure S7. Male genitalia. A–C Merodon clavipes (Fabricius, 1781) D–F M. italicus G–I M. dichopticus J–K M. fulcratus. A–B, D–E, G–H, J–K epandrium C, F, I, L hypandrium. A, C, D, F, G, I, J, L lateral view B, E, H, K ventral view. Abbreviations: al-anterior surstyle lobe, pl-posterior surstyle lobe. C, K place of ctenidium marked with arrow. Scale bar: 0.2 mm (A–F, J–L); 0.5 mm (G–I). Figure S8. Male genitalia. A–C Merodon alagoesicus Paramonov, 1925 D–F M. nigritarsis Rondani, 1845 G–I M. obstipus Vujić, Radenković & Likov, 2020. A–B, D–E, G–H epandrium C, F, I hypandrium. A, C, D, F, G, I lateral view B, E, H ventral view. Abbreviations: al-anterior surstyle lobe. Scale bar: 0.5 mm. Figure S9. Male genitalia. A–C Merodon pruni D–F M. hypochrysos Hurkmans, 1993 G–I M. serrulatus J–L M. hirtus. A–B, D–E, G–H, J–K epandrium C, F, I, L hypandrium. A, C, D, F, G, I, J, L lateral view B, E, H, K ventral view. Abbreviations: pl-posterior surstyle lobe. G basolateral protrusion marked with arrow. Scale bar: 0.5 mm (A–C); 0.2 mm (D–L). Figure S10. Male genitalia. A–C Merodon auronitens D–F M. caudatus G–I M. clunipes J–L M. crassifemoris. A–B, D–E, G–H, J–K epandrium C, F, I, L hypandrium. A, C, D, F, G, I, J, L lateral view B, E, H, K ventral view. Abbreviations: pl-posterior surstyle lobe, s-lateral sclerite of the aedeagus. A triangular basal extension marked with arrow F ventral processes of the hypandrium marked with arrow G apical hump marked with arrow. Scale bar: 0.2 mm (A–C, G–L); 0.5 mm (D–F). Figure S11. Male genitalia. A–C Merodon eumerusi D–F M. murinus G–I M. ottomanus. A–B, D–E, G–H epandrium C, F, I hypandrium. A, C, D, F, G, I lateral view B, E, H ventral view. Abbreviations: al-anterior surstyle lobe, pl-posterior surstyle lobe. Scale bar: 0.2 mm. Figure S12. Male genitalia. A–C Merodon capensis D–F M. desuturinus G–I M. neolydicus J–L M. planifacies. A–B, D–E, G–H, J–K epandrium C, F, I, L hypandrium. A, C, D, F, G, I, J, L lateral view B, E, H, K ventral view. Abbreviations: al-anterior surstyle lobe, s-lateral sclerite of the aedeagus. Scale bar: 0.2 mm. Figure S13. Male genitalia. A–C Merodon natans (Fabricius, 1794) D–F M. segetum. A, B, D, E epandrium C, F hypandrium. A, C, D, F lateral view B, E ventral view. Abbreviations: al-anterior surstyle lobe. Scale bar: 0.2 mm.
Figures S1–S15: Figures of adults
Data type: Adobe PDF file
Explanation note: Figure S1. Body of male. A, B Merodon albifrons Meigen, 1822 C, D M. constans (Rossi, 1794). A, C dorsal view B, D lateral view. Scale bar: 1 mm. Figure S2. Body of male. A, B Merodon equestris C, D M. geniculatus. A, C dorsal view B, D lateral view. Scale bar: 3 mm (A, B); 1 mm (C, D). Figure S3. Body of male. A, B Merodon ruficornis Meigen, 1822 C, D M. rufus. A, C dorsal view B, D lateral view. Scale bar: 1.5 mm. Figure S4. Body of male. A, B Merodon luteihumerus C, D M. mixtum. A, C dorsal view B, D lateral view. Scale bar: 2 mm. Figure S5. Body of male, dorsal view. A Merodon aureus Fabricius, 1805 B M. bessarabicus Paramonov, 1924 C M. cinereus (Fabricius, 1794) D M. chalybeus Wiedemann, 1822. Scale bar: 2 mm (A–C); 1.5 mm (D). Figure S6. Body of male, dorsal view. A Merodon caerulescens Loew, 1869 B M. dobrogensis C M. funestus D M. bombiformis. Scale bar: 1.5 mm (A, B), 2 mm (C, D). Figure S7. Body of male, dorsal view. A Merodon spinitarsis B M. nanus (Sack, 1931). Scale bar: 1 mm. Figure S8. Body of male, dorsal view. A Merodon aberrans B M. aurifer C M. avidus (Rossi, 1790) D M. italicus. Scale bar: 2 mm (A–C); 1.5 mm (D). Figure S9. Body of male. A–B Merodon clavipes (Fabricius, 1781) C M. fulcratus D M. serrulatus. A, C, D dorsal view B lateral view. Scale bar: 1 mm. Figure S10. Body of male. A, B Merodon pruni C M. nigritarsis Rondani, 1845 D M. auronitens. A, C, D dorsal view B lateral view. Scale bar: 2 mm (A–C); 1.5 mm (D). Figure S11. Body of male. A, B Merodon tarsatus C, D M. caudatus. A, C dorsal view B, D lateral view. Scale bar: 1.5 mm. Figure S12. Body of male. A, B Merodon clunipes C, D M. crassifemoris. A, C dorsal view B, D lateral view. Scale bar: 2 mm. Figure S13. Body of male, dorsal view. A Merodon eumerusi B M. hirtus C M. murinus D M. ottomanus. Scale bar: 1.5 mm (A, C); 2 mm (B, D). Figure S14. Body of male, dorsal view. A Merodon melanocerus B M. desuturinus C M. cuthbertsoni. Scale bar: 2 mm (A–B). Figure S15. Body of male, dorsal view. A Merodon natans (Fabricius, 1794) B M. segetum. Scale bar: 1.5 mm (A); 2 mm (B).
List of Merodon species grouped by lineage and species group
Data type: species data
Table S1. Classification of the genus Merodon in lineages and species groups, including an actual number of species within each
Data type: species data