Assessing the Diversity and Systematics of Brachyopini Hoverflies (Diptera: Syrphidae) in the Iberian Peninsula, Including the Descriptions of Two New Species

Simple Summary Hoverflies are a diverse family of insects (6000+ species) providing multiple ecosystem services and direct benefits to society, for example, in pollination and pest control. The extent to which hoverflies can benefit society depends on how well their basics are known, i.e., taxonomy (classification), biology and ecology. Small and inconspicuous hoverflies such as those of the genera Chrysogaster, Melanogaster, Lejogaster, Orthonevra and Riponnensia (tribe Brachyopini) do not usually catch the attention of the general public neither of scientists, and their classification is often poorly known at least in areas of their range. So, the aim of the present work is to gain knowledge in the classification of hoverflies by studying the species of the five genera above-mentioned in the Iberian Peninsula, which has one of the highest biodiversity levels in Europe. We discovered and described two new species from Spain, promoted a subspecies to species and proposed other nomenclatural acts to stabilise these hoverflies’ classification in Europe. Our results are reinforced with DNA analysis to locate the studied species in a wider systematic framework within the Brachyopini. Abstract Five genera of Brachyopini, Chrysogaster Meigen, 1800, Melanogaster Rondani, 1857, Lejogaster Rondani, 1857, Orthonevra Macquart, 1829 and Riponnensia Maibach et al. 1994a are here revised from the Iberian region. Two new species, Melanogaster baetica Ricarte and Nedeljković, sp. n. and Orthonevra arcana Ricarte and Nedeljković sp. n., are described from Spain, and a third species, Chrysogaster coerulea Strobl in Czerny and Strobl, 1909 stat. n., is reinstated as valid and redescribed. A lectotype is designated for Orthonevra plumbago (Loew, 1840). The holotype of Orthonevra incisa (Loew, 1843) and the lectotype of O. plumbago are described in detail and illustrated. Melanogaster baetica sp. n. is similar to Melanogaster parumplicata (Loew, 1840) in male genitalia morphology, while O. arcana sp. n. is similar to O. incisa in the entirely-pollinose sternum I and the conspicuous incision on the posterior margin of tergum V in female. The first Iberian record of Chrysogaster rondanii Maibach and Goeldlin de Tiefenau, 1995 is provided, whilst Melanogaster aerosa is removed from the Iberian checklist of Syrphidae. Identification keys are presented to the five Brachyopini genera and 18 species now reported from the Iberian Peninsula (Chrysogaster, 6 spp.; Lejogaster, 2 spp.; Melanogaster, 3 spp.; Orthonevra, 5 spp.; Riponnensia, 2 spp.). COI (Cytochrome c oxidase subunit I) barcodes of the two new species plus C. coerulea, Chrysogaster solstitialis (Fallén, 1817), Orthonevra nobilis (Fallén, 1817) and Orthonevra frontalis (Loew, 1843) were successfully obtained from Spanish specimens. A COI-based tree was produced to locate these taxa in a wider systematic framework within the tribe.

Insects 2022, 13,648 3 of 45 also examined. The collection acronym is indicated, together with a unique specimen code, after the number of males/females examined from each locality/date/collector. Examined material from Spain was as old as 119 years, but also included specimens recently collected by the authors of the present paper in different fieldwork campaigns in 2019-2021. Actual specimens were examined alongside literature on Iberian Brachyopini. For the examined material, novel data are indicated as 'new', and data on specimens published prior to the present study as 'revised'. For non-examined material, published references are provided as 'additional published records'.

Morphological Study
Species morphology was studied with a binocular microscope Leica M80. For descriptions, the following parameters were measured on one or more ('n') of the studied adult specimens: (a) body length (L), measured from the antennal insertions to the tip of the abdomen; (b) wing length (WL), measured from the tegula to the wing apex; (c) length/width ratio of the basoflagellomere, measured as the width at its maximum and the length from the most distal point of the pedicel to the basoflagellomere apex. In the species descriptions/redescriptions, measurements of the holotype/neotype are given, as well as a range of measurements from a number of specimens (n) in brackets. Measurements were taken with the software Leica Application Suite X (LAS X) ® (v. 3.0.4.16529) from a specimen image made with a camera (Leica DFC 450) attached to a binocular microscope (Leica M205 C). Adult images were created as stacks of photos with the same equipment and software. Male genitalia were dissected in most cases for species confirmation and comparison. Genitalia were dissected following Ricarte et al. [17], but usually increasing the boiling time up to 10 min due to their high level of sclerotization. Male genitalia were drawn from individual images taken with the above-mentioned equipment and traced on a light table. Morphological terminology follows Thompson [18], except for the term 'hair/s', which is used in replacement of 'pilis/pile'. For the male genitalia, terminology followed Maibach et al. [6]. For the illustrations cited from other publications, 'figure' is used in the text after a literature citation in square brackets, while for those original from the present work ' Figure' is used elsewhere.

Molecular Study
DNA was extracted both from one mesoleg and one metaleg of three males of Chrysogaster coerulea Strobl in Czerny and Strobl (1909), eight specimens of C. solstitialis (four males and four females), five paratypes of the new Melanogaster species (three males and two females), three paratypes of the new Orthonevra species (one male and two females), two specimens of O. frontalis (one male and one female), two males of O. nobilis and two males of R. splendens using the NZY Tissue gDNA Isolation kit following the manufacture's protocol for animal tissues. PCR amplifications of the 5 end of the Cytochrome c oxidase subunit I (COI-5 ) gene were performed with the universal primers LCO1490  and HCO2198   [19]. All amplifications were carried out in a total volume of 25 µL containing 1× of Buffer reaction, 0.4 mM of dNTPs, 0.2 µM of each primer, 2 mM of MgCl 2 and 1 unit of NZYTaq II DNA polymerase. Thermocycler conditions followed Ståhls and Barkalov [20] but annealing at 47-49 • C. PCR products were visualized with an electrophoresis process in a 1% agarose gel and sequenced at Macrogen Inc. (Macrogen, Madrid, Spain).
The COI-5 barcode sequences obtained were edited by eye with the program Sequencher v. 5.4.6 (Gene Codes Corporation 2017, Ann Arbor, MI, USA). Then, COI-5 sequences of each species of Chrysogaster Meigen, 1803, Lejogaster Rondani, 1857, Melanogaster Rondani, 1857and Orthonevra Macquart, 1829 available at the public repositories Gen-Bank and BOLD [21] were downloaded (see Table 1). For the molecular analyses, we excluded barcodes of specimens non-identified at the species level. First, alignment was performed automatically with MAFFT online service [22], which was checked by eye with Insects 2022, 13, 648 4 of 45 the program AliView v.1.25 [23]. The final matrix had a length of 658 bp. Neighbourjoining (NJ) and maximum likelihood (ML) analyses were carried out in MEGA7 [24] with 1000 bootstrap replications. The NJ analysis was performed using the maximum composite likelihood model [25] and the ML analysis with the general time reversible [26] model with a gamma distribution (+G). This was the second evolutionary model proposed by the Corrected Akaike Information Criterion (AICc, 3749.85)-the first model was TIM2+I+G (3735.25)-using the software jModelTest v.2.1.10 [27]. The resulting trees were rooted based on a Ceriana vespiformis (Latreille, 1809) sequence. Additionally, the evolutionary divergence between barcode sequences was also estimated using the maximum composite likelihood model with a gamma distribution (0.168) in MEGA7 (see Table S1 of Supplementary Materials).

New Brachyopini Species
Melanogaster baetica Ricarte and Nedeljković, sp. n. (Figures 1, 2A      Diagnosis. This species can be distinguished from all other Melanogaster species by the following combination of features: black body with blue reflections ( Figure 1); basoflagellomere roundish (Figure 2A), 0.7-0.9× longer than wide; vertical triangle with long black to dark brown hairs ( Figure 2A); eye contiguity half the length of frontal triangle in dorsal view (males); in male, face with a slight but conspicuous tubercle centrally ( Figure 2A); in female, occiput wholly white pilose, males with some black hairs; wing with a conspicuous large brown pigmented area anteriorly ( Figure 1B,D); scutum with long erect white to yellowish white hairs, and a few long black hairs intermixed ( Figure 2B); in males, abdomen with subparallel lateral sides ( Figure 1B); in females, face flat, without tubercle ( Figure 1C); surstylus of male genitalia, in lateral view, expanded subapically and then tapering abruptly in a short apex ( Figure 3A).
Description. MALE (holotype). Overall appearance ( Figure 1). Black body with blue reflections; L = 7 mm (6.3-7.1 mm, n = 4); WL = 5.6 mm (5.2-5.6 mm, n = 4). Head (Figure 2A). Eye with short sparse hairs; scape black; pedicel black, turning brownish black at the apex, with a few hairs ventrally and dorsally; basoflagellomere brownish black; arista longer than antenna (nearly 1.5×), dark brown, bare; basoflagellomere roundish ( Figure 2A), 0.9× longer than wide (0.7-0.9×, n = 4); ocellar triangle conspicuously elevated, equilateral; vertical triangle with long black to dark brown hairs ( Figure 2A); eye contiguity slightly longer than the vertical triangle, but half the length of frontal triangle in dorsal view; frontal triangle swollen (Figure 2A), shiny, coarsely punctured, with a slight medial excavation on the lower part; frontal triangle with long (as long as an antenna), black to dark brown hairs, shorter towards the antennae; lunule shiny, brownish black; face with a fascia of brown sparse pollinosity just below antennal insertions, from eye to eye; face finely wrinkled laterally, with a small but conspicuous tubercle centrally; face with white to brown hairs, except for the bare area below antennal insertions and tubercle; facial hairs shorter near the mouth; occiput with very sparse pollinosity, much denser on the eye margin; occiput with short white hairs, longer and black to brown dorsally. Thorax. Wing wholly microtrichose, with veins black to dark brown, except for orange basal part of Sc and CuA; pterostigma brownish black; wing with a conspicuous large brown pigmented area antero-centrally ( Figure 1B,D); hairs on vein C black; vein M 1 non-recessive ( Figure 1B,D); squama yellowish white; halter with pedicel orange, but blackish base and capitulum; legs black, slightly lighter at the apices of meso-and metatibiae; leg hairs white to light yellow, except for the black hairs on protibia, ventral part of metafemur, and the setulae at the apex of mesotibia and tarsi (also some black hairs on tarsi dorsally); leg hairs longer on the postero-ventral part of pro-and mesofemora, with individual hairs wavy apically; legs sparsely pollinose; scutum shiny, sparsely (and inconspicuously) pollinose anteriorly and laterally; scutum with long erect white to yellowish white hairs ( Figure 2B), and a few long black hairs intermixed; scutellum with both long and short white hairs intermixed; some long hairs of mesonotum with wavy apices; scutellum with a posterior slight sulcus; pleuron with white to light yellow hairs, except for the bare anterior anepisternum (ventrally with a small patch of hairs), dorso-medial and posterior anepimeron, katepimeron, meron and metasternum; katepisternum with a large bare area between the dorsal and ventral patches Insects 2022, 13, 648 9 of 45 of hairs; anterior spiracle light orange; posterior spiracle dark brown. Abdomen. Elongated, with subparallel lateral sides ( Figure 1B); in dorsal view, narrower than scutum at the maximum scutum width; thickly pollinose (dull) except for shiny lateral margins of terga II-IV, lateral margin of tergum I pollinose anteriorly; terga with white to light yellow hairs, short and recumbent centrally, conspicuously longer laterally, especially on the anterior corners of tergum II; all sterna shiny except for the entirely pollinose sternum I; sterna with white hairs, long and erect on sternum II, somewhat shorter and semi-recumbent on sternum III, recumbent on sternum IV; genitalia as in Figure 3, with surstylus more or less expanded subapically and then tapering abruptly in a short stocky apex, and hypandrium with a blunt projection on the outer side; superior lobe of the aedeagus cover with two opposite teeth of different size, the inner tooth much longer than the outer. FEMALE ( Figure 1C,D). Same as male except for the following: L = 6.8 mm; WL = 5.4 mm; basoflagellomere 0.8× longer than wide, orangey brown; frons with white to yellowish white hairs, as long as scape or nearly so, just slightly longer and forwardly inclined on the ocellar triangle; profile of the frons angled near antennae, i.e., with an abrupt change along the profile line of the frons near antennae in lateral view ( Figure 1C); posterior part of frons with a differentiated medial sulcus bearing less hair density than contiguous parts of the frons; anterior part of frons (posterior to the frons angle) with slight lateral wrinkles diagonal to eye margin; face flat, without tubercle; face with pollinose triangular fascia; head without black hairs; apices of all femora narrowly brown; tarsi somewhat lighter than male; mesonotum with shorter hairs than male, as long as pedicel; abdomen roundish oval ( Figure 1D), slightly wider than scutum at the maximum scutum width; tergum IV pollinose only on the anterior margin; tergum V entirely shiny; hairs of terga following the same pattern as in male, but of shorter length in general; sterna with shorter hairs than male, all semi-recumbent; sterna III and IV pollinose on the anterior margins.
Etymology. The specific epithet 'baetica', meaning Baetic in Latin, refers to the Spanish mountain range where most specimens of this species have been collected, the Baetic System.
Range. Spain (provinces of Alicante, Granada and Jaén). Biology. Adults visit flowers of Cistus monspeliensis L. (Cistaceae) and Euphorbia nicaeensis All. (Euphorbiaceae). They can be found near streams (e.g., in 'Tornillos de Gualay') where their larvae are suspected to find their breeding sites. Adult records are from mid-April to late June. In the south of Spain, this species has been found from 1575-1895 m asl.
Taxonomic notes. This species is most similar to M. parumplicata, from which it can be distinguished by genitalic characters in males. For example, in the lateral view, (a) the surstylus of the new species is more or less expanded subapically and then tapers abruptly in a short stocky apex ( Figure 3A), whilst in M. parumplicata, the subapical expansion is absent [9] (figure 21); (b) the projection of the outer side of the hypandrium is blunter in M. baetica sp. n. ( Figure 3A) than in M. parumplicata [9] (figure 21). In addition, the long hairs of the scutum are mostly white to yellowish in males of M. baetica sp. n. but mostly dark brown to black in M. parumplicata ( Figure 2D). As for the male (Figure 2A,C), the female of M. baetica sp. n. ( Figure 1C) is similar to that of M. parumplicata in the face profile [7], but the female of M. baetica sp. n. has only white hairs on the occiput, whilst the examined females of M. parumplicata have at least some black hairs or setulae on the occiput. There is also a difference in the pollinose facial band in females. In M. parumplicata, this band is narrow laterally, while centrally, it is expanded towards the mouth, but in M. baetica sp. n., this fascia is wider laterally, in the shape of an inverted triangle.
The North African species Melanogaster lindbergi Kassebeer, 1999a is also similar to M. baetica sp. n., but they can be easily separated by the shape of the surstylus and the superior lobe of the aedeagus cover. The surstylus of M. lindbergi, in lateral view, is clearly notched subapically [8] (figure 3), whilst in M. baetica sp. n., it lacks this notch ( Figure 3A). In addition, M. lindbergi has two opposite teeth of about the same size in the superior lobe of the aedeagus cover [8] (figure 3), but M. baetica sp. n. has a much longer tooth pointing towards the inner side of the hypandrium ( Figure 3B). In the similar M. aerosa, the superior lobe of the aedeagus cover has a tooth pointing towards the outer side of the hypandrium,          Diagnosis. This species can be distinguished from all other Orthonevra species by the following combination of features: basoflagellomere 1-1.2× longer than wide, in females usually shorter than in males ( Figure 5B,D); katepisternum with two separate patches of hairs and, in between, a patch of shorter hairs; metafemur with black hairs ventrally; sternum I pollinose; male genitalia as in Figure 7, with surstylus tapering towards the apex in lateral view, and hypandrium with asymmetric superior lobes bearing a spur on their inner side; in females, tergite V folds laterally giving it a triangular shape in dorsal view ( Figure 6C), usually bearing a small apical keel ( Figure 6B) that, in dorsal view, looks like a tooth or spina ( Figure 6C); posterior margin of tergum V with a central incision reaching the keel.
MALE (holotype). Overall appearance ( Figure 4A,B). Black body with dark olive-green reflections; L = 6.3 mm (5.2-6.3 mm, n = 4); WL = 5.3 mm (4.3-5.3 mm, n = 4). Head ( Figure 5A). Eye with very short-but obvious-scatted hairs; scape black; pedicel black, turning lighter at the apex, with a few long white hairs ventrally, and some shorter black hairs dorsally; basoflagellomere orange, blackish brown dorso-apically ( Figure 5B); arista not longer than antenna, blackish brown, virtually bare ( Figure 5B); basoflagellomere 1.1× longer than wide (1.1-1.2×, n = 4) ( Figure 5B); head hairs all white to light yellow ( Figure 5A); ocellar triangle slightly elevated, virtually equilateral; vertical triangle with long forwardly curved whitish-yellow hairs; eye contiguity as long as the ocellar triangle; frontal triangle coarsely punctured, shiny, with sparse bronze pollinosity, slightly excavated above lunule; frontal triangle with whitish-yellow hairs, shorter ventrally; lunule shiny black; face with a fascia of white pollinosity just below antennal insertions, from eye to eye; face finely wrinkled; in profile, face straight below antennae, then curving forwards until the projected ventral part ( Figure 5A); occiput pollinose; in profile, ventral part of head straight ( Figure 5A). Thorax. Black; wing wholly microtrichose, with veins black, except for basal part of Sc and R1; pterostigma brownish black; vein M 1 recessive ( Figure 6A); squama yellowish white; halter light orange; legs black ( Figure 4A); leg hairs white to light yellow, except for the black hairs on the ventral part of metafemur and the setulae on tarsi; leg hairs longer on the postero-ventral part of pro-and mesofemora; profemur with an antero-ventral semi-circular lamina apically; mesonotum with short white to light yellow hairs, somewhat longer and slightly backwards inclined on the anterior half of scutum, and also longer (but straight) on the posterior margin of scutellum; scutellum with a slight sulcus posteriorly; pleuron with white to light yellow hairs, except for the bare anterior anepisternum (ventrally with a small patch of hairs), dorso-medial and posterior anepimeron, katepimeron, meron and metasternum; katepisternum with a dorsal patch of hairs and a ventral patch, as well as a third patch of shorter hairs in between; anterior spiracle light orange; posterior spiracle light yellow. Abdomen. Oval, black; in dorsal view, slightly wider than scutum at the maximum scutum width ( Figure 4B); thickly pollinose (dull) except for shiny lateral margins of all terga; with short white to light yellow hairs, conspicuously longer on the anterior corners of tergum II and very short on the central areas of terga; all sterna shiny except for the entirely pollinose sternum I; sterna black ( Figure 4A), with long erect hairs on sternum II, shorter and slightly inclined hairs on sterna I and III, hairs on sternum IV recumbent; genitalia as in Figure 7, with surstylus tapering towards the apex in lateral view, and hypandrium with asymmetric superior lobes bearing a spur on their inner side; apico-dorsal lobe of aedeagus with a developed hook-like process pointing towards the outer side of the hypandrium, and a smaller hook-like process basal to the large one.
FEMALE. Same as male except for the following: L = 6.4-7 mm (n = 5); WL = 5.2-6 mm (n = 5); basoflagellomere 1-1.2× (n = 6) longer than wide ( Figure 5D); frons with hairs somewhat longer than scape, longer and forwardly inclined on the ocellar triangle; frons transversally wrinkled ( Figure 4D), except for a medial smooth line. Anterior and posterior spiracles grey. Abdomen black, roundish oval, in dorsal view, wider than scutum at the maximum scutum width (more than in male) ( Figure 4D); tergum V triangular in dorsal view, with each lateral margin of triangle twice, or more, the medial length of the triangle ( Figure 6C); lateral sides of tergum V might or might not be visible in dorsal view, but always inclined downwards ( Figure 6B); posterior corner of the triangular part of tergum V usually bearing a small keel ( Figure 6B) that, in dorsal view, is seen as a tooth or spina ( Figure 6C); tergum V with a central incision reaching the keel; sterna black ( Figure 4C), somewhat lighter on sterna I and II; sternum I with erect hairs; sternum II with semirecumbent hairs; sterna III to V with recumbent hairs.
Etymology. The specific epithet 'arcana', formed from the Latin 'arcanum' for secret or mystery, refers to the fact that the status of this species has proved difficult to resolve, as a mystery.
Range. Spain (provinces of Ciudad Real, Jaén, Madrid and Salamanca). Biology. Adults visit flowers of Salix atrocinerea Brot. near small rivers where the larvae of this species are suspected to find their microhabitats. The species has also been recorded visiting flowers of wild Pyrus sp. (Pyrus bourgaeana Decne.) and Crataegus sp. Most records are from late winter / early spring (February to April), except for one that was collected as late as early June.
Taxonomic notes. This species is similar to O. incisa in having the sternum I entirely pollinose, and in females, a conspicuous incision on the posterior margin of tergum V. However, the new species can be separated from O. incisa by the shape of vein M 1 , which is recessive in the new species (as in all Orthonevra) ( Figure 6A) but not recessive in O. incisa [7] (figure 12C). Males can also be clearly separated by the shape of their genitalia (Figures 7 and 14). In the female, the triangle of the tergum V seen dorsally is conspicuously shorter in O. arcana sp. n. ( Figure 6C) than in O. incisa ( Figure 13C). The new species can be readily separated from O. plumbago by the pollinose sternum I, shiny in O. plumbago. Czerny and Strobl, 1909 stat. n.

Chrysogaster coerulea Strobl in
The species Chrysogaster coerulea is represented in the Figures 8, 9, and 10C.   Gabriel Strobl, in Czerny and Strobl [35], proposed coerulea as a new variety of Chrysogaster chalybeata Meigen. Essentially, coerulea was used to name the Spanish specimens with a bluish head, thorax and abdomen (specially females) and with the central part of the wing more darkened than in the typical form (both sexes). Strobl [35] wrote on page 207 'chalybeata Mg., basalis Str. (non Loew?), var. coerulea m. Escorial, 2♂♂, 4♀♀, Spanien, ♂, ♀ (L)', i.e., he was apparently referring to eight specimens collected by Jorge Lauffer ('L'), six from 'Escorial' and two from 'Spanien'. Strobl [35] suggested that C. basalis of Loew could in fact be a variety of C. chalybeata based on the observed similarity with the new coerulea. Whether all eight mentioned specimens belonged to the new variety or also included specimens of C. basalis examined by Strobl is uncertain.
In the Strobl's collection, which is deposited in Admont, Austria (BSA), there are not specimens labelled as coerulea, but the variety is listed on page 689 of the main BSA handwritten Collection Catalogue as 'v. coerulea m. Spanien I♂ II♀' [36]. Evenhuis and Pape [37] assume that the type series for coerulea of Strobl consists of two males and four females, but this is uncertain under the light of the BSA Collection Catalogue, which refers to one male and two females. In the MNCN collection, there are several specimens of Lauffer catalogued as 'Chrysogaster sp.', but none of those have identification labels. However, other non-Chrysogaster specimens from the MNCN bear Strobl's identification labels. So, we interpret that the Lauffer's unlabelled specimens of Chrysogaster from the MNCN do not belong to the type series of coerulea, even if seven of these unlabelled specimens are from 'El Escorial' and could have been collected at the same time as the type material of coerulea. In fact, Gil-Collado [16] states that there are no specimens of C. chalybeata, neither of the typical form, nor of coerulea, in the MNCN collection at the time he studied it.
Evenhuis and Pape [37] consider that the name coerulea should be treated as infrasubspecific and then unavailable. The valid name Evenhuis and Pape [37] give for coerulea is Chrysogaster coemiteriorum, as C. chalybeata is regarded as a junior synonym of C. coemiteriorum. However, there are not enough grounds to believe that coerulea was described as an infrasubspecific entity. Strobl [35] described a geographical subspecies when proposing coerulea for specimens from a certain region, Spain, where the typical ('European') form of C. chalybeata was meant to be absent by then. Thus, following the article 45.6.4 of the Code, the name coerulea is to be treated as subspecific.
The seven Chrysogaster specimens from 'El Escorial' of Lauffer's collection (MNCN) were examined, and the males shared genitalia morphology with recently collected males from other Spanish localities. One male from Lauffer's collection did not have a blue shine, probably because it was a teneral when collected. However, the males from other Spanish localities and specially their females had a conspicuous blue shine, as suggested for coerulea in Strobl's description. We interpret all these specimens correspond to Strobl's concept Gabriel Strobl, in Czerny and Strobl [35], proposed coerulea as a new variety of Chrysogaster chalybeata Meigen. Essentially, coerulea was used to name the Spanish specimens with a bluish head, thorax and abdomen (specially females) and with the central part of the wing more darkened than in the typical form (both sexes). Strobl [35] wrote on page 207 'chalybeata Mg., basalis Str. (non Loew?), var. coerulea m. Escorial, 2 ♂♂, 4 ♀♀, Spanien, ♂, ♀(L)', i.e., he was apparently referring to eight specimens collected by Jorge Lauffer ('L'), six from 'Escorial' and two from 'Spanien'. Strobl [35] suggested that C. basalis of Loew could in fact be a variety of C. chalybeata based on the observed similarity with the new coerulea. Whether all eight mentioned specimens belonged to the new variety or also included specimens of C. basalis examined by Strobl is uncertain.
In the Strobl's collection, which is deposited in Admont, Austria (BSA), there are not specimens labelled as coerulea, but the variety is listed on page 689 of the main BSA handwritten Collection Catalogue as 'v. coerulea m. Spanien I ♂II ♀' [36]. Evenhuis and Pape [37] assume that the type series for coerulea of Strobl consists of two males and four females, but this is uncertain under the light of the BSA Collection Catalogue, which refers to one male and two females. In the MNCN collection, there are several specimens of Lauffer catalogued as 'Chrysogaster sp.', but none of those have identification labels. However, other non-Chrysogaster specimens from the MNCN bear Strobl's identification labels. So, we interpret that the Lauffer's unlabelled specimens of Chrysogaster from the MNCN do not belong to the type series of coerulea, even if seven of these unlabelled specimens are from 'El Escorial' and could have been collected at the same time as the type material of coerulea. In fact, Gil-Collado [16] states that there are no specimens of C. chalybeata, neither of the typical form, nor of coerulea, in the MNCN collection at the time he studied it.
Evenhuis and Pape [37] consider that the name coerulea should be treated as infrasubspecific and then unavailable. The valid name Evenhuis and Pape [37] give for coerulea is Chrysogaster coemiteriorum, as C. chalybeata is regarded as a junior synonym of C. coemiteriorum. However, there are not enough grounds to believe that coerulea was described as an infrasubspecific entity. Strobl [35] described a geographical subspecies when proposing coerulea for specimens from a certain region, Spain, where the typical ('European') form of C. chalybeata was meant to be absent by then. Thus, following the article 45.6.4 of the Code, the name coerulea is to be treated as subspecific.
The seven Chrysogaster specimens from 'El Escorial' of Lauffer's collection (MNCN) were examined, and the males shared genitalia morphology with recently collected males from other Spanish localities. One male from Lauffer's collection did not have a blue shine, probably because it was a teneral when collected. However, the males from other Spanish localities and specially their females had a conspicuous blue shine, as suggested for coerulea in Strobl's description. We interpret all these specimens correspond to Strobl's concept of coerulea, and they clearly differ from C. coemiteriorum and C. basalis in various features including the male genitalia, which is different from any other genitalia of Chrysogaster species in the literature. Thus, the status of coerulea is now formally upgraded to species level as Chrysogaster coerulea, a name already used in Peck's catalogue [5] as a synonym of C. chalybeata but without further explanation.
The species concepts of C. coerulea and allies have never been clear. For example, Gil-Collado [16] illustrated the head of C. basalis in lateral view, but his drawing had in fact a more protruding facial tubercle than in the specimens currently studied of this species. The present paper shows that C. coerulea has a more protruding facial tubercle than any other similar species, and Gil-Collado [16] possibly drew the head of C. coerulea. This evident confusion together with the fact that the type series of C. coerulea is lost suggest the need to clarify the taxonomic status of C. coerulea through the designation of a neotype and detailed redescription of this taxon. The specimen designated here as neotype is a male from the original type locality, El Escorial, and by the same collector as the original type material, Lauffer (MNCN). The male, which has both slight blue shine and wing pigmentation (teneral?), shares genitalia morphology with recently collected males showing heavier blue shine and wing pigmentation. Upon the examination of all available material, the darker wing referred by Strobl for C. coerulea appears to be somewhat variable and so, not a good character as the facial tubercle or male genitalia.
Type material. NEOTYPE. SPAIN • ♂; Escorial; Lauffer leg.; colección Lauffer; MNCN, MNCN_Ent 301518 (blue label); as Chrysogaster basalis in Gil-Collado [16]. Redescription. MALE (based on a specimen with typical colouration of this species from 'La Granja, Segovia'). Overall appearance (Figure 8). Black body with bluish reflections; L = 7.03 mm (6.19-7.31 mm, n = 4); WL = 5.1 mm (4.6-5.75 mm, n = 4). Head ( Figure 10C). Eye with short sparse yellow hairs, almost bare in the ventral part; scape black; pedicel brownish with a few hairs ventrally and dorsally; basoflagellomere brownish, orangereddish ventrally ( Figure 10C); arista longer than antenna, dark brown, bare; basoflagellomere roundish ( Figure 10C), 1.25× longer than wide (0.95-1.5×, n = 4); ocellar triangle conspicuously elevated, equilateral; vertical triangle with long black hairs; eye contiguity two times longer than the vertical triangle, frontal triangle shiny black, with medial excavation from antennal insertions to posterior 2/3 of length of frontal triangle; frontal triangle with long black hairs, lunule shiny, black; face with a fascia of brown sparse pollinosity just below antennal insertions, from eye to eye, the fascia about as wide as a third of the face width; face finely wrinkled laterally, with a slight but conspicuous shiny black tubercle medially; face with short, scarce yellow hairs, except for the bare area below antennal insertions and tubercle; occiput with very sparse pollinosity, much denser on the eye margin; occiput with black hairs. Thorax. Wing wholly microtrichose, with veins black to dark brown, except for orange basal part of Sc, CuA, CuP and A1 ( Figure 8A,C); pterostigma brownish black; wing with a conspicuous large brown pigmented area antero-apically ( Figure 8A,C); hairs on vein C black; calypteres yellowish white; halter with pedicel orange, but blackish base and capitulum; legs black; leg hairs black, except yellow hairs in the anterior part of meso-and metafemora; meso-and metafemora with two rows of black setulae ventrally; setulae on pro-and metatarsi yellow, on mesotarsi black; legs sparsely pollinose except profemora which are shiny posteriorly; scutum shiny, black with bluish reflections, sparsely (and inconspicuously) pollinose anteriorly; scutum with semi-recumbent black hairs and black setulae intermixed; scutellum shining black with long black hairs in the posterior margin; scutellum with a posterior slight sulcus; pleuron with white to light yellow hairs, except for the bare anterior anepisternum (ventrally with a small patch of hairs), posterior anepimeron, katepimeron, meron and metasternum; katepisternum with a large bare area between the dorsal and ventral patches of hairs; anterior spiracle light orange; posterior spiracle dark brown. Abdomen. Oval-shaped ( Figure 8B); thickly pollinose (dull) except for shiny lateral margins of terga II-IV, and posterior margin of tergum IV; terga with light yellow short and recumbent hairs; tergum I with long yellow hairs on the lateral margins, tergum II with long yellow recumbent hairs in its anterior part; all sterna shiny except for the entirely pollinose sternum I; sterna with white hairs, erect on sternum I, shorter and recumbent on sterna II-IV; genitalia as in Figure 9, with the superior lobes of the aedeagus cover elongated, straight and approximated to each other along most of their length ( Figure 9B,C); aedeagus cover with blunt upper corners ('shoulders') in ventral view ( Figure 9C). FEMALE ( Figure 8B,D). Same as male except for the following: L = 5.96-7.84 mm; WL = 4.48-5.86 mm; basoflagellomere 0.9-1.03× longer than wide (n = 4). L = 6.35 mm; WL = 5.31 mm (n = 4); usually with more vivid blue reflections than males; basoflagellomere 0.99 × longer than wide (n = 4), brown; frons with scarce short, yellow hairs, as long as diameter of ocellus or nearly so; frons surface angled near antennae; posterior part of frons with a differentiated medial sulcus of conspicuous width, sulcus with lower hair density; anterior part of frons (posterior to the frons angle) with lateral wrinkles diagonal to eye margin; face flat, without tubercle; pollinose fascia of face of triangular shape; mesonotum only with short black setulae; abdomen roundish oval, slightly wider than scutum at the maximum scutum width ( Figure 8D); tergum V entirely shiny; hairs of terga following the same pattern as in male; sterna with shorter hairs than in male, all semi-recumbent.
Biology. Adults visit flowers of Euphorbia nicaeensis All. (Euphorbiaceae) and Magydaris panacifolia (Apiaceae). They can be found in localities near streams (e.g., in 'La Granja, arroyo del Pto. del Paular') where their larvae are suspected to find their breeding sites. Adult records are from mid-June to late August.
Taxonomic notes. Males of this species can be distinguished from the similar C. basalis by the presence of a facial tubercle, which is absent in C. basalis ( Figure 10A). The facial tubercle of C. coerulea is more expressed than that in C. solstitialis ( Figure 10B). From the similar C. solstitialis, C. coerulea can be separated by the shiny or just partly pollinose proepimeron, which is extensively pollinose in C. solstitialis. The wing base of C. coerulea is light yellow, whilst in C. solstitialis is dark brown. The females of C. coerulea can be distinguished from those of other Chrysogaster species by the combination of blue reflections in the thorax and orangey yellow wing base ( Figure 8B,D). However, females of C. coerulea and C. basalis are sometimes difficult to separate from each other, because there are some females of C. coerulea with less conspicuous bluish shine and some females of C. basalis with blue shine at least in the pleuron.
The facial tubercle of C. coerulea is also more expressed than in C. mediterraneus, in which it is just slightly produced [9] (figure 1). Male of C. coerulea is also similar to Chrysogaster musatovi Stackelberg, 1952 in the straight and approximated superior lobes of the aedeagus cover, but C. musatovi differs, for example, (a) in the facial tubercle, which is inconspicuous in C. musatovi (see photo of the holotype at http://www.zin.ru/collections/ Diptera/specimen_en.html?Catalog_UID=1345139328343005 accessed on 1 February 2022) but obvious in C. coerulea ( Figure 10C), and (b) in the shape of the surstylus [41] (figure 5) ( Figure 9A).
The male genitalia of C. coerulea (Figure 9) are similar to those of C. basalis, C. solstitialis and Chrysogaster mediterraneus Vujić, 1999. Unlike the other Chrysogaster species, the superior lobes of the aedeagus cover of C. coerulea are straight and approximated to each other along most of their length ( Figure 9B,C). In the ventral view ( Figure 9C), the aedeagus cover of C. coerulea has much less pronounced 'shoulders' than in C. solstitialis. The superior lobes of the aedeagus cover of C. mediterraneus are shorter than in C. coeruela.

The Holotype of Orthonevra incisa (Loew, 1843)
Examined material. Hermann Loew described this species from a female collected in 'Posen' on 1st May (1843). Maibach et al. [7] indicated that there is a female in Loew's collection (ZMB, Berlin) that is, unquestionably, the type of C. incisa. This specimen was located in the ZMB by the authors of the present paper and confirmed to be the type of this taxon. The specimen, in good condition, is labelled as follows: 1♀, 'Posen 1. aedeagus cover of C. coerulea has much less pronounced 'shoulders' than in C. solstitialis. The superior lobes of the aedeagus cover of C. mediterraneus are shorter than in C. coeruela.

The Holotype of Orthonevra incisa (Loew, 1843)
Examined material. Hermann Loew described this species from a female collected in 'Posen' on 1st May (1843). Maibach et al. [7] indicated that there is a female in Loew's collection (ZMB, Berlin) that is, unquestionably, the type of C. incisa. This specimen was located in the ZMB by the authors of the present paper and confirmed to be the type of this taxon. The specimen, in good condition, is labelled as follows: 1♀, 'Posen 1.  Redescription. FEMALE HOLOTYPE. Overall appearance ( Figure 11A,B). Black body with bluish grey reflections; L = 6.7 mm; WL = 6.1 mm. Head ( Figure 12A). Eye bare, with scattered hairs only visible at high magnification; scape blackish orange; pedicel blackish orange, with a few long yellowish white hairs ventrally, and some shorter hairs of the same colour dorsally; basoflagellomere orange, slightly darker dorso-apically; arista not longer than antenna, dark orange, virtually bare; basoflagellomere roundish (0.9× longer than wide) ( Figure 12B); head hairs all white to light yellow; ocellar triangle slightly elevated; distance between hind ocelli slightly greater than distance between the front ocellus and a hind ocellus; frons with short hairs (as long as scape), somewhat longer and forwardly inclined on the ocellar triangle; frons transversally wrinkled on eye margins, smooth along a medial line; lunule orangey brown; face with a fascia of white pollinosity just below antennal insertions, from eye to eye; face slightly wrinkled, smoother on the forwardly projected ventral part; in profile, face straight for a short length below antennae, then curving forwards until the projected ventral part; occiput pollinose, more sparsely towards the vertex; in profile, ventral part of head gently curved towards the projected part. Thorax. Black; wing wholly microtrichose, with veins brown to orange; pterostigma light orange; vein M 1 non-recessive, with its anterior end almost perpendicular to R 4+5 ( Figure 12C); squama yellowish white; halter orange; legs dark brown to black; leg hairs white to light yellow, except for some black setulae on the ventral part of tarsi; leg hairs longer on the postero-ventral part of pro-and mesofemora; profemur with an antero-ventral semi-circular lamina apically; mesonotum with short white to light yellow hairs, both slightly longer and backwards inclined on the anterior half of scutum, and also longer (but straight) on the posterior margin of scutellum; scutellum with a slight sulcus posteriorly; pleuron with short white to light yellow hairs, except for the bare anterior anepisternum (ventrally with a small patch of hairs), dorso-medial and posterior anepimeron, katepimeron, meron and metasternum; katepisternum with a dorsal and a ventral patch of hairs; anterior spiracle light grey; posterior spiracle orange. Abdomen. Oval, brownish black; in dorsal view, wider than scutum at maximum scutum width; sparsely pollinose (dull) except for shiny lateral margins of all terga; with short white to light yellow hairs, conspicuously longer on the anterior corners of tergum II; tergum V with slightly longer hairs than the other terga ( Figure 13A); tergum V triangular in dorsal view, lateral margin of triangle less than twice the medial length of the triangle ( Figure 13C); lateral sides of tergum V folded giving the triangular dorsal appearance ( Figure 13A,B); posterior margin of tergum V with a central incision nearly reaching the tip of the dorsal triangular part of the tergum ( Figure 13B); all sterna shiny except for the entirely pollinose sternum I; sterna orange, darker in sternum I and V, with white short recumbent hairs.
Taxonomic notes. During the course of the present study, five specimens of O. incisa from Poland were examined and compared with the female holotype, also from Poland. The Polish females were conspecific with the female holotype but somewhat variable in the shine colour of body (darker in the recent females), scape colour (black in the recent females), colour of wing veins (black to blackish brown, except for the orange basal sections of veins, in the recent females), and colour of metafemur hairs, which are all white in the holotype ( Figure 12D) (some black scattered hairs might be present ventrally, on the apical half of metafemur in the recent females). Variation is attributed to the age of the holotype specimen (179 years old) or to the fact that this was more teneral when collected in 1843. The Polish males (Figure 14), also considered conspecific with the female holotype, had the same genitalia as that illustrated for O. incisa by Stackelberg [42].  Taxonomic notes. During the course of the present study, five specimens of O. incisa from Poland were examined and compared with the female holotype, also from Poland. The Polish females were conspecific with the female holotype but somewhat variable in the shine colour of body (darker in the recent females), scape colour (black in the recent females), colour of wing veins (black to blackish brown, except for the orange basal sections of veins, in the recent females), and colour of metafemur hairs, which are all white in the holotype ( Figure 12D) (some black scattered hairs might be present ventrally, on the apical half of metafemur in the recent females). Variation is attributed to the age of the holotype specimen (179 years old) or to the fact that this was more teneral when collected in 1843. The Polish males (Figure 14), also considered conspecific with the female holotype, had the same genitalia as that illustrated for O. incisa by Stackelberg [42].

The Lectotype of Orthonevra plumbago (Loew, 1840)
Examined material. Hermann Loew described this species from the 'area of Posen Poland from an undetermined number of specimens of unknown sex. According to Even huis and Pape [37], the type of O. plumbago is deposited in the ZMB collection (Berlin where we found two-apparently-conspecific females labelled as 'typus': 1♀, 'plumbag Lw' (handwritten), 'Coll. H. Loew' (printed); 1♀, 'Orthoneura plumbago m' (handwri ten), '12929' (printed), 'Coll. H. Loew' (printed), 'Zool. Mus. Berlin' (printed), '96' (hand Examined material. Hermann Loew described this species from the 'area of Posen', Poland from an undetermined number of specimens of unknown sex. According to Evenhuis and Pape [37], the type of O. plumbago is deposited in the ZMB collection (Berlin), where we found two-apparently-conspecific females labelled as 'typus': 1♀, 'plumbago Lw' (handwritten), 'Coll. H. Loew' (printed); 1♀, 'Orthoneura plumbago m' (handwritten), '12929' (printed), 'Coll. H. Loew' (printed), 'Zool. Mus. Berlin' (printed), '96' (handwritten in a triangular label, doubtful writing) ( Figure 15C). The first female is abdomenless and wingless, while the second is in good condition. Hermann Loew used 'm' after a name to indicate a taxon was described by him; this pattern is also found in the labels of the holotype of Chrysogaster incisa Loew, 1843 (see under this species section). Given that the two females found are also labelled as types, and they meet (at least the complete female) the features provided in the original description of O. plumbago, we consider them part of the type series and designate here the female labelled 'Orthoneura plumbago m' as lectotype (the other becomes a paralectotype). Description. FEMALE LECTOTYPE. Overall appearance ( Figure 15A,B). Black body with bluish reflections; L = 6.3 mm; WL = 5.4 mm. Head ( Figure 16A). Eye bare; scape blackish brown; pedicel brown, with a few long white hairs ventrally, and some shorter white and brown hairs intermixed dorsally; basoflagellomere brown, baso-ventrally orange; arista not longer than antenna, brown, virtually bare; basoflagellomere elongate (1.3× longer than wide), with round apex ( Figure 16B); head hairs all white to light yellow; Description. FEMALE LECTOTYPE. Overall appearance ( Figure 15A,B). Black body with bluish reflections; L = 6.3 mm; WL = 5.4 mm. Head ( Figure 16A). Eye bare; scape blackish brown; pedicel brown, with a few long white hairs ventrally, and some shorter white and brown hairs intermixed dorsally; basoflagellomere brown, baso-ventrally orange; arista not longer than antenna, brown, virtually bare; basoflagellomere elongate (1.3× longer than wide), with round apex ( Figure 16B); head hairs all white to light yellow; ocellar triangle slightly elevated; distance between hind ocelli greater than distance between the front ocellus and a hind ocellus; frons with short hairs (as long as scape), longer and forwardly inclined on the ocellar triangle; frons transversally wrinkled on eye margins, smooth along a medial line that tapers towards the ocellar triangle; lunule brown, contrasting with the darker frons; face with a narrow fascia of white pollinosity just below antennal insertions, from eye to eye; face slightly wrinkled, smooth on the forwardly projected ventral part; in profile, face just slightly convex, almost straight; occiput sparsely pollinose, densely along a narrow line on eye margin; in profile, ventral part of head entirely straight. Thorax. Black; wing wholly microtrichose, with veins brown to orange ( Figure 16C); pterostigma yellowish orange; vein M 1 recessive ( Figure 16C); squama whitish orange; halter orange; legs dark brown to black, with somewhat lighter coxae and trochanters; leg hairs white to light yellow, except for some black spiny hairs on the ventral part of the apical section of metafemur, and some black setulae on the ventral part of tarsi; leg hairs longer on the postero-ventral part of pro-and mesofemora; mesonotum with short (not longer than scape), erect, white to light yellow hairs; scutum with 3-4 inconspicuous vittae on the anterior margin; scutellum with a slight sulcus posteriorly; pleuron with short white to light yellow hairs, except for the bare anterior anepisternum (ventrally with a small patch of hairs), dorso-medial and posterior anepimeron, katepimeron, meron and metasternum; anterior spiracle grey; posterior spiracle brown. Abdomen. Oval, brownish black; in dorsal view, wider than scutum at the maximum scutum width; sparsely pollinose (dull) except for shiny lateral margins of all terga; with short white to light yellow hairs, conspicuously longer on the anterior corners of tergum II, on the posterior margin of tergum IV, and on tergum V; tergum IV with a small wart-like elevation in the middle of posterior margin; posterior corners of tergum IV downwards directed, forming a triangle continuous with tergum V in dorsal view; tergum V with a medial sulcus starting on the posterior margin as a narrow short incision (partly broken) and then extending almost to the anterior margin as a seam (in posterior view, the sulcus divides the tergum giving it the appearance of two valves) ( Figure 17B); in lateral view, tergum V rounded, with the sulcus dorso-ventrally orientated ( Figure 17A); all sterna shiny, orange (sternum V darker), with white recumbent hairs, longer along the medial line of sterna and on the entire sternum V ( Figure 17C).
Taxonomic notes. The lectotype of O. plumbago would not key out with existing keys. For example, with van Veen [43], the lectotype would key out only to couplet 2, because the basoflagellomere is neither as long as wide, nor 1.5−2× longer than wide. Even if the length/width ratio of the basoflagellomere of the lectotype is interpreted as intraspecific variability of an elongate basoflagellomere, the lectotype would not key out to O. plumbago because it has not a deep incision at hind margin of tergite V ( Figure 17B), as indicated in van Veen [43]. With Bartsch et al. [44], the lectotype would key out to the couplet 4 (O. brevicornis and O. plumbago), but O. plumbago would be unreachable because the basoflagellomere of the lectotype is less than 1.5−2× longer than wide ( Figure 16B), and the hind margin of tergite V does not have a sharp-edged ridge, but a seam all along most of the medial tergite length ( Figure 17B). Speight and Castella [45] use a 'provisional' concept of O. plumbago based on Stackelberg [42] and indicate that this species female can be separated from O. brevicornis by the deep incision on the posterior half of the tergite V that sort of divides the tergite in two halves. Again, an incision as such, drawn also in Haarto and Kerppola [46], is absent from the proposed lectotype ( Figure 17B).
Stackelberg [47], which modifies Stackelberg [42] in part, provides in a key some features approaching the here-designated lectotype to his own concept of O. plumbago; for example, he indicates that the female of O. plumbago has a small elevation on the posterior margin of tergite IV, as in the lectotype. However, he also indicates that the hairs on the mesonotum are 2−3 times longer than the arista base, but the lectotype has longer hairs in this body part, and that the narrow incision of the tergite V almost reaches its anterior margin, but the lectotype has a very short incision that soon becomes a seam towards the anterior margin ( Figure 17B). Any of the mentioned references address the apparently characteristic curved orientation of the sulcus of tergite V in the lectotype ( Figure 17A).
A female of O. plumbago from Vorkuta (Russia) collected by Gerard Pennards was examined from photos. This female shared morphology with the lectotype, including the shape of the tergum V. However, the incision of the tergum V was deeper than that in the lectotype. Thus, the length of the incision appears to be variable in O. plumbago. Given the confusion found in the literature with this species, females of O. plumbago identified in Europe and the European parts of Russia should be now revised by comparison with the featured lectotype and reported variability in certain features (e.g. length of the posterior incision in tergum V of female). Regarding males sensu Stackelberg [42], further morphological and molecular analyses should be undertaken to confirm whether those of O. plumbago are conspecific with the lectotype-like females. ish orange; halter orange; legs dark brown to black, with somewhat lighter coxae and tro chanters; leg hairs white to light yellow, except for some black spiny hairs on the ventra part of the apical section of metafemur, and some black setulae on the ventral part of tars leg hairs longer on the postero-ventral part of pro-and mesofemora; mesonotum wit short (not longer than scape), erect, white to light yellow hairs; scutum with 3-4 incon spicuous vittae on the anterior margin; scutellum with a slight sulcus posteriorly; pleuro with short white to light yellow hairs, except for the bare anterior anepisternum (ventrall with a small patch of hairs), dorso-medial and posterior anepimeron, katepimeron, mero and metasternum; anterior spiracle grey; posterior spiracle brown. Abdomen. Oval, brown ish black; in dorsal view, wider than scutum at the maximum scutum width; sparsel pollinose (dull) except for shiny lateral margins of all terga; with short white to light ye low hairs, conspicuously longer on the anterior corners of tergum II, on the posterior mar gin of tergum IV, and on tergum V; tergum IV with a small wart-like elevation in th middle of posterior margin; posterior corners of tergum IV downwards directed, formin a triangle continuous with tergum V in dorsal view; tergum V with a medial sulcus start ing on the posterior margin as a narrow short incision (partly broken) and then extendin almost to the anterior margin as a seam (in posterior view, the sulcus divides the tergum giving it the appearance of two valves) ( Figure 17B); in lateral view, tergum V rounded with the sulcus dorso-ventrally orientated ( Figure 17A); all sterna shiny, orange (sternum V darker), with white recumbent hairs, longer along the medial line of sterna and on th entire sternum V ( Figure 17C).  Taxonomic notes. The lectotype of O. plumbago would not key out with existi For example, with van Veen [43], the lectotype would key out only to couplet 2, the basoflagellomere is neither as long as wide, nor 1.5−2× longer than wide. Ev length/width ratio of the basoflagellomere of the lectotype is interpreted as intr variability of an elongate basoflagellomere, the lectotype would not key out to O. p because it has not a deep incision at hind margin of tergite V ( Figure 17B), as ind van Veen [43]. With Bartsch et al. [44], the lectotype would key out to the coup brevicornis and O. plumbago), but O. plumbago would be unreachable because the b ellomere of the lectotype is less than 1.5−2× longer than wide ( Figure 16B), and margin of tergite V does not have a sharp-edged ridge, but a seam all along mo medial tergite length ( Figure 17B). Speight and Castella [45] use a 'provisional' co O. plumbago based on Stackelberg [42] and indicate that this species female can rated from O. brevicornis by the deep incision on the posterior half of the tergite V of divides the tergite in two halves. Again, an incision as such, drawn also in Ha Kerppola [46], is absent from the proposed lectotype ( Figure 17B).
Stackelberg [47], which modifies Stackelberg [42] in part, provides in a key s

Key to the Studied Brachyopini genera
The key presented below is adapted from Maibach et al. [6].

4.
Basoflagellomere brownish black ( Figure 2A); tergum II with short to very short hairs on its central area; in male, face sometimes slightly concave, with a conspicuous medial tubercle (Figure 2A,C) . . . Melanogaster (go to Section 3.5.3) -Basoflagellomere orange to red ( Figure 10); tergum II often with long recumbent hairs on its central area; in males, face straight, usually with a less-conspicuous medial tubercle ( Figure 10A,B), sometimes with a bumped area at each side . . . Chrysogaster (go to Section 3.5.1)

Chrysogaster Meigen, 1803
Below is a key to the Iberian species of Chrysogaster. In many cases, dissection of the male genitalia is crucial to confirm the species identification in this genus.

5.
Scutum with very-short sparse pilosity, especially noticeable on the posterior part (hairs shorter than the diameter of a posterior ocellus

Discussion
After the present work, the total number of species of the five studied genera of Brachyopini grows from 15 to 18 in the Iberian-Balearic region: Chrysogaster, 6 spp.; Lejogaster, 2 spp.; Melanogaster, 3 spp.; Orthonevra, 5 spp.; Riponnensia, 2 spp. The small size of these hoverflies, their similar overall appearance and look when flying in the field, and the difficulty to identify females-and males, in the absence of dissected genitalia-have limited the number of studies on their regional faunas and taxonomy. Although various recent monographs include keys to genera/species (e.g., van Veen [43], Bartsch et al. [44]), the present work is the second after Vujić [9] devoted at the regional revision of the abovementioned Brachyopini genera in Europe and the first in revising their species diversity in the south-west of the continent.
The distribution of many brachyopines is now better understood in the Iberian region as a result of the present work. For example, Chrysogaster basalis, which was thought to be present in various Spanish provinces from the very south (Cádiz) to the very north (Huesca) [14], is now confirmed only from the northern provinces of Huesca and Teruel,

Discussion
After the present work, the total number of species of the five studied genera of Brachyopini grows from 15 to 18 in the Iberian-Balearic region: Chrysogaster, 6 spp.; Lejogaster, 2 spp.; Melanogaster, 3 spp.; Orthonevra, 5 spp.; Riponnensia, 2 spp. The small size of these hoverflies, their similar overall appearance and look when flying in the field, and the difficulty to identify females-and males, in the absence of dissected genitalia-have limited the number of studies on their regional faunas and taxonomy. Although various recent monographs include keys to genera/species (e.g., van Veen [43], Bartsch et al. [44]), the present work is the second after Vujić [9] devoted at the regional revision of the abovementioned Brachyopini genera in Europe and the first in revising their species diversity in the south-west of the continent.
The distribution of many brachyopines is now better understood in the Iberian region as a result of the present work. For example, Chrysogaster basalis, which was thought to be present in various Spanish provinces from the very south (Cádiz) to the very north (Huesca) [14], is now confirmed only from the northern provinces of Huesca and Teruel, suggesting that the Iberian distribution of the actual C. basalis is more limited than previously expected to be. Another interesting example is Lejogaster tarsata. The only (and old) Spanish record of this species was from the Girona province [16]. In the mid-twentieth century, it was reported from Andorra [50], and it was just recently incorporated to the Portuguese checklist of hoverflies [12]. The disperse distributional record of this species suggested that it should occur in a wider area, and, in fact, we found an old specimen (year 1905) collected in Jaramiel (Valladolid, Spain), somewhere in between Girona and Portugal. At the European level, the finding of C. rondanii is especially important, since this species had been confirmed only from the Netherlands, Germany, Belgium, France, Czechia and Switzerland [74]. The male of C. rondanii reported from Ávila represents the southernmost record of this species in Europe.
The results obtained for the genus Chrysogaster address the fact that synonyms are sometimes proposed without a detailed taxonomic analysis behind. The Spanish endemic variety coerulea of C. chalybeata was proposed by Strobl in Czerny and Strobl [35]. Authors such as Andréu [52] and Gil-Collado [16] retained the use of this variety name. After a long temporal gap, this variety was upgraded to the species level and given as a synonym of C. chalybeata in the catalogue by Peck [5]. Works of reference in brachyopines, e.g., [6], did not mention this variety. However, the finding of males with blue shine and distinctive genitalia ( Figure 9) prompted us to search the literature, and this led to the conclusion that these males coincided with Strobl's concept of coerulea. This is not the only example of species incorrectly synonymised in Syrphidae, as indicated by the results of studies such as Nedeljković et al. [75] and Marcos-García et al. [76]. Chrysogaster coerulea separates clearly in the COI-based tree from all other species of Chrysogaster analysed (Figure 18), confirming that the morphological singularity of Spanish populations of Chrysogaster described by Strobl in 1909 addressed to a valid taxon. Additionally, within Chrysogaster, C. solstitialis appears to represent a single taxon from the morphological and molecular point of view (Figure 18), from the Iberian Peninsula to Scandinavia, all across Europe.
The Melanogaster study resulted in the description of M. baetica sp. n. from Spain and the elimination of M. aerosa from the Iberian-Balearic checklist of Syrphidae. This latter species is confirmed from central and northern Europe and, further south, only from high mountains of Montenegro [9]. Most specimens of M. aerosa (also as C. macquarti in literature) from the Iberian region were revised and confirmed to belong to other Melanogaster species, so it is just plausible that M. aerosa is really absent from this southern region of Europe. However, the related species M. baetica sp. n. is well represented in the Baetic mountain system of Spain. This new Spanish endemic species is morphologically most similar to M. parumplicata, which is confirmed from central and northern Europe but also from mountains of France, Switzerland, Bosnia and Herzegovina and Montenegro. The new Melanogaster species is also similar to M. hirtella, but the male of this latter species is unique in having a conspicuously elongated apex of the surstylus, much shorter and stockier in M. baetica sp. n. ( Figure 3A); M. hirtella also has darker (brown) hairs on the scutum than M. baetica sp. n., which has white to yellowish white hairs. Melanogaster baetica sp. n. may have evolved in isolation in the Iberian Peninsula, where the close M. parumplicata may also be present in high northern mountains such as the Pyrenees, but unexpected further south. Melanogaster aerosa, M. baetica sp. n., M. parumplicata and the North African species M. lindbergi appear to belong to the same species group due to their similar morphology, especially in their male genitalia [7][8][9]. From the molecular point of view, M. hirtella, with slightly more differentiated male genitalia, would also belong to the same clade as the above-mentioned species (Figure 18).
The better understanding of the O. incisa concept as well as the description of O. arcana sp. n. confirm that a shiny or slightly pollinose sternum I cannot be taken as diagnostic for Orthonevra, because these two species have a wholly pollinose sternum I, unlike all other European species of this genus [6]. Orthonevra arcana sp. n. and O. incisa share the pollinose sternum I with Chrysogaster/Melanogaster, but Orthonevra and Chrysogaster/Melanogaster differ in various other morphological characters. Curiously, Moran et al. [11] recovered the genera Orthonevra and Chrysogaster within the same molecular clade. A new group, the O. incisa group, is morphologically defined in this preliminary study for species sharing a pollinose sternum I, females with tergum 5 triangular in dorsal view and with a posterior incision (of variable size), and males with asymmetric superior lobes of the aedeagus cover. The specimen of O. frontalis is close to O. tristis and O. arcana sp. n. in the tree, but this grouping might just be accidental, since the bootstrap support for the clade containing all the three species is 51 ( Figure 18). Fresh material of O. incisa and additional molecular markers are necessary to test the putative relationship between this species and O. arcana sp. n.. Thus, a new gene-based tree would be expected to show O. arcana sp. n. and O. incisa grouping together in the same clade.
Molecular analyses in the present work indicate that the species of some of the studied genera differ clearly in the COI-5 marker, while those of other genera have a lower degree of differentiation in this marker but are still different morphologically. For example, the divergence values amongst morphologically distinct species of Orthonevra range from 3-21%, while amongst species of Melanogaster, they are just up to 1% (see Table S1 of Supplementary Materials). Despite the fact that more than 90% of congeneric species in the Diptera have high values of divergence in the COI-5 barcodes, there is a 3% of cases for which the divergence is low between valid species [77]. A similar morphology combined with low genetic divergence among species are clear indicators of closely related species [78]. Furthermore, the low genetic divergence between congeneric species in Lejogaster and Melanogaster may suggest that these genera have been originated in a recent speciation process [79]. Nevertheless, the morphological and molecular data supported our species concepts and confirmed the validity of the two new species and C. coerulea. This differential variation in the COI-5 for genera that are now affiliated to Brachyopini may indicate that this tribe is in fact paraphyletic, in accordance with the findings by Moran et al. [11]. Therefore, a complete sampling together with the use of further molecular markers would be necessary to test phylogenetic relationships in those genera involving less-differentiated species such as those of Melanogaster or Lejogaster and more-differentiated as in Chrysogaster and Orthonevra.
Brachyopines of the five studied genera are hoverflies with aquatic or semiaquatic saprophagous larvae found in plant-rich mediums. Thus, adults are usually observed near small water courses, ponds, and bogs [80], as confirmed in our study with many localities including aquatic habitats (e.g., 'La Font del Mas dels Arbres' and 'Ibon Espelunchiella'). The habitats of the studied brachyopines are especially vulnerable to droughts and changes of any sort in their water regimes. In fact, some of the studied species are catalogued under a threatened category in Europe, C. basalis as Vulnerable (VU) [81], C. rondanii as Endangered (EN) [74] and R. longicornis also as Endangered (EN) [82]. Special attention should be paid to these latter two species and a better assessment of their population trends and specific threats in the Iberian Peninsula should also be undertaken for their conservation.

Conclusions
Morphological and molecular evidence was combined to update the taxonomy and systematics of Iberian brachyopines. According to the main aim of this work, the conclusions are as follows: (1) A total of 18 species of Chrysogaster, Lejogaster, Melanogaster, Orthonevra and Riponnensia (Brachyopini) are present in the Iberian-Balearic Region. Chrysogaster coerulea is reinstated as a valid species and M. aerosa is removed from the Iberian checklist. A lectotype is designated for the non-Iberian species Orthonevra plumbago. This is the first work devoted to update the taxonomy, systematics, and distribution of Brachyopini in the Iberian area.

Informed Consent Statement: Not applicable.
Data Availability Statement: All sequences generated in this work are available in the publicly accessible repository of GenBank (https://www.ncbi.nlm.nih.gov/genbank/).