Merodon rojoi, Zorić & Ačanski & Vujić & Ståhls & Djan & Radenković, 2020

Zorić, Ljiljana Šašić, Ačanski, Jelena, Vujić, Ante, Ståhls, Gunilla, Djan, Mihajla & Radenković, Snežana, 2020, Resolving the taxonomy of the Merodon dobrogensis species subgroup (Diptera: Syrphidae), with the description of a new species, The Canadian Entomologist 152 (1), pp. 36-59 : 52-56

Merodon rojoi Radenkovi´c and Vujić, new species

http://zoobank.org/ urn:lsid:zoobank.org:act:F2208118-FA92-4F29-834D-2307F7FA0665

Type specimens. Holotype: ♂, Greece: Mountain Erymanthos , Kalentzi, 37.95039ºN, 37.95039ºE, 2.ix.2012, 1212 m, A. Vujić ( NMW) . Paratypes: Greece: 1♂, Euboea, Nea Artaki, 18.ix.1982, Bette ( BMNH) (misidentified as M. dobrogensis in Radenković et al. 2011) ; 2♀♀, Attiki, Dafni , 10 km

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W of Athena , 28.ix. 1985, 199 m ( RMNH 03074 ) (misidentified as M. dobrogensis in Petanidou et al. 2011 and Radenković et al. 2011) ; 1♂, Argolida , Korfos-Epidavros, 15–27.ix. 1986, 136 m, Wolf ( RMNH 04157 ) (misidentified as M. dobrogensis in Radenković et al. 2011) ; 8♂♂, 10♀♀, Mountain Erymanthos , Kalentzi, 2.ix.2012, 1212 m, A. Vujić ( FSUNS G2374 - G2384 , G2386 - G2391 , G2393 ) ; 1♀, Mountain Pindos , above Katara, 3.ix.2012, 1200 m, A Vujić ( FSUNS G2392 ) ; 1♀, Mountain Olympus (on Prospero autumnale ), 22.ix. 2013, 632 m, A. Vujić ( FSUNS AL12 ) .

Diagnosis. Eyes covered with sparse, grey pile, shorter than pedicel ( Figs. 23, 26), mostly black in the Merodon dobrogensis species complex (as on Figs. 25, 28). In the male, pile on scutum is as long as pedicel; mostly pale, with two maculae of black pile around wing basis and transverse suture; in the female, short black pile (as long as half of pedicel) covers most of the scutum ( Figs. 29–30). Wing infuscation similar to M. dobrogensis . Posterior quarter of sternum IV in the male with sparse, black pile. Additionally, it differs from taxa belonging to the M. dobrogensis species complex by morphometric characters of wing and male genitalia ( Figs. 3–4, 8–9), distribution ( Fig. 21), COI and COI ND4 tree topologies ( Figs. 11–12), COI and ND4 unique haplotypes, as well as unique 28S rRNA gene genotype. Differs from M. dobrogensis in its elevational range ( Fig. 22).

Description. Male ( Fig. 32): Head ( Figs. 23, 26): Antenna ( Fig. 26) reddish brown, basoflagellomere 2.5 times as long as wide, 1.6–1.7 times longer than pedicel, concave, and darkened dorsally, apex rectangular; arista dark brown and thickened basally, slightly shorter than the basoflagellomere. Face and frons black with blue lustre, covered with long whitish-yellow pile. Oral margin bare with black lustre. Vertical triangle isosceles, shiny black, predominantly covered with black pile, and posteriorly with long, white pile. Ocellar triangle equilateral. Eye contiguity about 11 ommatidia long. Vertical triangle: eye contiguity: ocellar triangle = 1.5:1.5:1. Eye pile sparse, grey. Occiput with whitish-yellow pile, along the eye margin with dense white microtrichia and posteriorly with metallic bluish-green lustre.

Thorax: Postpronotum with conspicuous tooth-like process posteriorly. Scutum and scutellum black with metallic blue lustre, covered with short, erect white to yellow pile, except black pile around wing basis and transverse suture. Posterior anepisternum, anepimeron, and posterodorsal part of katepisternum with long whitish-yellow pilosity and metallic blue lustre. Wing with dense

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microtrichia, brown, infuscate especially basally, anteriorly and along veins; veins dark brown except light brown C, Sc, and basal part of R1. Calypter grey yellow. Halter with light brown pedicel and dark brown capitulum. Femora dark brown with pale apex; profemur and mesofemur with a stripe of light yellow pile posteriorly and very short, black pile anteriorly and dorsally; metafemur with very short, black pile. Tibiae and tarsi orange, except 2 (3) apical tarsomeres darkened (fourth tarsomere distinctly brown), covered with yellow pilosity and some black pile. Metatrochanter with an inner calcar with two pointed angles.

Abdomen ( Fig. 33): Oval, slightly longer than mesonotum; reddish brown; tergum I black with golden lustre; tergum II reddish-brown with small black marking medially, and two lateral indistinct white microtrichose spots near the black marking; tergum III reddish brown; tergum IV reddish brown, black posteriorly; pile on terga predominantly short golden, except black pile on black markings and posterior margins of terga II and III. Sterna translucent, from reddish yellow to reddish brown towards the end of abdomen, black lined, covered with long whitish-yellow pile, except few black pile on posterior quarter of sternum IV.

Male genitalia: Similar to all other species of the Merodon aureus species group ( Figs. 13–14): posterior surstylar lobe with parallel margins and rounded apex ( Fig. 13) and a narrow, elongate, sickle-shaped hypandrium without lateral sclerite of aedeagus ( Fig. 14).

Female. ( Figs. 17, 24, 27, 34): Similar to the male except for the normal sexual dimorphism and for the following characteristics: metatrochanter ( Fig. 17) without thorn; black markings on terga

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( Fig. 34) narrower or absent; tergum II with more conspicuous two lateral white microtrichose spots and terga III and IV with distinct stripes of white pilosity; tergum V and sternum V black. Length: body 11–12 mm, wing 8–9 mm.

Etymology. The new species is named after the Spanish entomologist Santos Rojo and is dedicated to his comprehensive work on syrphids. Additionally, “rojo” in Spanish language means red, indicating the red abdomen in this species.

Natural history. Preferred environment: forest; small, open areas in evergreen Quercus and Pinus forests. Flowers visited: Prospero autumnale . Flight period: Autumn (September). Larva unknown.

Discussion

With their red abdomen, species from the Merodon dobrogensis species subgroup have clearly different morphological features compared to all other species within the M. aureus species group. Merodon dobrogensis was described from Romania ( Bradescu 1982), and for a long time, there were no additional records of this species. Radenković et al. (2011) described the morphologically very similar species M. puniceus from the island of Lesvos, but since there were no genetic data on M. dobrogensis , it was impossible to unambiguously resolve the taxonomy of this species. Continental material from central, south, and west of Greece, referred to as M. dobrogensis in Petanidou et al. (2011) as well as Radenković et al. (2011), are the here-described M. rojoi . During 2013 and 2014, we collected new specimens of M. dobrogensis in Romania and eastern Greece and here we confirm that they belong to one nominal species based on molecular data, morphology, wing geometric morphometry, and distribution. Additionally, we validate M. puniceus as a separate species based on genetic, wing, and surstylus morphometry differentiations. These two species form the M. dobrogensis species complex.

New distributional data of Merodon puniceus have been recorded in the western part of the Anatolian Peninsula, representing the first known mainland sites for this species. Previously, this species has been listed as endemic for Lesvos Island, Greece (Radenković et al. 2011). The specimens from Turkey are firstly assigned to M. puniceus based on the similarity of DNA barcode sequences to one from Lesvos Island (Supplementary Table S1 ), which is then

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supported based on the integrative taxonomy approach applied here. The distributional pattern of M. puniceus is in agreement with the earlier study of Merodon fauna in the Aegean region (Vujić et al. 2016). Namely, the fauna of large islands not very remote from the nearest mainland, such as Lesvos or Samos, is closely related to the adjacent mainland fauna. These two islands host approximately half of the Merodon species previously classified as Anatolian (Ståhls et al. 2016; Vujić et al. 2016).

Merodon rojoi , which is morphologically similar to both abovementioned taxa, has been discovered in the central, south, and west parts of Greece. This species has some unique morphological features that separate it from the M. dobrogensis species complex, and it is resolved as a separate monophyletic clade, supported with high bootstrap values on COI and COI ND4 trees. Additionally, it has unique COI and ND4 haplotypes as well as 28S rRNA genotype. Moreover, M. rojoi differs significantly in its wing and surstylus shape from species from the M. dobrogensis species complex, with an excellent percentage of correct species classification by both discriminant analyses (both wing and surstylus 100%) and the Gaussian-naïve Bayes classifier analyses (wing 97%; surstylus 100%). Apart from the significant differences in wing and surstylus shapes among all the three species, the position of specimens in both canonical variate analysis scatter plots clearly illustrates the division of the M. dobrogensis species subgroup into M. rojoi and M. dobrogensis species complex. This segregation is also noticeable when comparing species mean wing and surstylus shapes, with the lowest differences being within the M. dobrogensis species complex.

In general, molecular findings support wing and surstylus shape differentiation among species from the Merodon dobrogensis species subgroup. These results are not surprising, given that congruence between molecular and geometric morphometrics results in the recent taxonomic studies of syrphid species becomes standard (Nedeljković et al. 2013, 2015; Vujić et al. 2013; Ačanski et al. 2016; Šašić et al. 2016, 2018; Chroni et al. 2018; Kočiš Tubić et al. 2018; Radenković et al. 2018). Moreover, based on both simple and partial Mantel tests, there is no significant correlation of wing and surstylus shape and genetic differentiation with climate and geographic proximity among the investigated species.

The low average uncorrected p distances (p COI, p ND4) between the two species from the Merodon dobrogensis species complex suggest that they diverged recently and probably during the late Pleistocene. However, a high COI sequence divergence between the M. rojoi and M. dobrogensis complex species indicates a much earlier divergence of the M. rojoi lineage from the M. dobrogensis complex ancestor lineage. The speciation process is probably related to the complex geological history of the Aegean region and severe climatic oscillation during the Pleistocene epoch, as has been suggested for many other Merodon taxa inhabiting the Mediterranean and sub-Mediterranean regions (e.g., Petanidou et al. 2011; Ačanski et al. 2016; Šašić et al. 2016; Vujić et al. 2016; Radenković et al. 2018). Also, it may be connected to their larval natural history/host plant relationships, which remain unknown.

The applied integrative approach once again proved useful in resolving the taxonomy of Merodon species. The M. dobrogensis species subgroup was successfully resolved using molecular data, geometric morphometry, and distributional data in addition to morphological character states analyses.