An assessment of new character in hoverfly species delimitation using linear and geometric morphometrics – genus Merodon Meigen, 1803 (Diptera: Syrphidae) as a case study

Keywords: cryptic species delimitation, hoverflies, R4 5 vein, taxonomy, wing venation


Detection of morphologically indistinguishable cryptic species implies using an integrative taxonomic approach with a combination of molecular, contemporary morphological, ecological and other relevant analyses. Within a contemporary morphological analysis, two approaches are commonly used in hoverfly taxonomy: a geometric morphometric analysis of the wing and surstyle shape. Here, the importance of the R4+5 vein shape is tested in cryptic species delimitation within four Merodon species groups using linear and semilandmark geometric morphometric analyses. As expected, geometric morphometrics showed a stronger resolution compared to linear morphometrics. Linear morphometrics failed to detect differences related to sexual dimorphism or differences among the species M. pruni and M. obscurus. However, all cryptic species and sexes were separated with high significance based on the R4+5 vein shape. Moreover, obtained results concurred with the landmark-defined wing shape and molecular results published in previous studies. Additionally, combining two characters, the semilandmark R4+5 vein shape and the landmark-defined wing shape, provided more detailed and precise insights into the shape differences. Our results showed that the R4+5 vein shape stands out as an important character in species delimitation of hoverflies where the sinuation of this vein is present. Therefore, it can be beneficial as a single character or in combination with a landmark-based wing shape analysis.


Ačanski J., Vujić A., Djan M., Vidaković D.O., Ståhls G. & Radenković S. 2016. Defining species boundaries in the Merodon avidus complex (Diptera, Syrphidae) using integrative taxonomy, with the description of a new species. European Journal of Taxonomy 237: 1–25.

Ačanski J., Vujić A., Šašić Zorić Lj., Radenković S., Djan M., Ristić Z.M. & Ståhls G. 2022. Merodon chalybeus subgroup: an additional piece of the M. aureus group (Diptera, Syrphidae) puzzle. Annales Zoologici Fennici 59: 79–109.

Aracil A., Ačanski J., Pérez-Bañón C., Šikoparija B., Miličić M., Campoy A., Radenković S., Vujić A., Radišić P. & Rojo S. 2022. Characterization of preimaginal developmental stages of two cryptic South African species of the Merodon planifacies complex (Diptera: Syrphidae: Eristalinae: Merodontini), with differentiation through morphometry analysis. Arthropod Structure & Development 70: 101187.

Baracchi D., Dapporto L. & Turillazzi S. 2011. Relevance of wing morphology in distinguishing and classifying genera and species of Stenogastrinae wasps. Contributions to Zoology 80 (3): 191–199.

Birdsall K., Zimmerman E., Teeter K. & Gibson G. 2000. Genetic variation for the positioning of wing veins in Drosophila melanogaster. Evolution & Development 2 (1): 16–24.

Chaiphongpachara T. & Laojun S. 2019. Effectiveness of landmark-and semi-landmark-based geometric morphometric to identify four species of Culex mosquitoes in Thailand. Journal of Advanced Veterinary and Animal Research 6 (3): 278–283.

Chroni A., Grković A., Ačanski J., Vujić A., Radenković S., Veličković N., Djan M. & Petanidou T. 2018. Disentangling a cryptic species complex and defining new species within the Eumerus minotaurus group (Diptera: Syrphidae), based on integrative taxonomy and Aegean palaeogeography. Contributions to Zoology 87 (4): 197–225.

de Souza A.L.D.S., Multini L.C., Marrelli M.T. & Wilke, A.B.B. 2020. Wing geometric morphometrics for identification of mosquito species (Diptera: Culicidae) of neglected epidemiological importance. Acta Tropica 211: 105593.

Djan M., Ståhls G., Veličković N., Ačanski J., Vidaković D.O., Rojo S., Pérez-Bañón C., Radenković S. & Vujić A. 2020. The Merodon planifacies subgroup (Diptera, Syrphidae): congruence of molecular and morphometric evidences reveal new taxa in Drakensberg mountains valleys (Republic of South Africa). Zoologischer Anzeiger 287: 105–120.

Gushki R.S., Lashkari M. & Mirzaei S. 2018. Identification, sexual dimorphism, and allometric effects of three psyllid species of the genus Psyllopsis by geometric morphometric analysis (Hemiptera, Liviidae). ZooKeys 737: 57–73.

Klingenberg C.P. 2011. MorphoJ: an integrated software package for geometric morphometrics. Molecular Ecology Resources 11: 353–357.

Kočiš Tubić N., Ståhls G., Ačanski J., Djan M., Obreht Vidaković D., Hayat R., Khaghaninia S., Vujić A. & Radenković S. 2018. An integrative approach in the assessment of species delimitation and structure of the Merodon nanus species group (Diptera: Syrphidae). Organisms Diversity & Evolution 18: 479–497.

Li R., Zhang H., Li S. & Bai M. 2017. Geometric morphometric analysis of Eysarcoris guttiger, E. annamita and E. ventralis (Hemiptera: Pentatomidae). Zoological Systematics 42 (1): 90–101.

Likov L., Vujić A., Kočiš Tubić N., Djan M., Veličković N., Rojo S., Pérez-Bañón C., Veselić S., Barkalov A., Rüstem H. & Radenković S. 2020. Systematic position and composition of Merodon nigritarsis and M. avidus groups (Diptera, Syrphidae) with a description of four new hoverflies species. Contributions to Zoology 89: 74–125.

Moraes E.M., Manfrin M.H., Laus A.C., Rosada R.S., Bomfin S.C. & Sene F.M. 2004. Wing shape heritability and morphological divergence of the sibling species Drosophila mercatorum and Drosophila paranaensis. Heredity 92: 466–473.

Mutanen M. & Pretorius E. 2007. Subjective visual evaluation vs. traditional and geometric morphometrics in species delimitation: A comparison of moth genitalia. Systematic Entomology 32 (2): 371–386.

Nedeljković Z., Ačanski J., Vujić A., Obreht D., Ðan M., Ståhls G. & Radenković S. 2013. Taxonomy of Chrysotoxum festivum Linnaeus, 1758 (Diptera: Syrphidae) — an integrative approach. Zoological Journal of the Linnean Society 169: 84–102.

Nedeljković Z., Ačanski J., Đan M., Obreht-Vidaković D., Ricarte A. & Vujić A. 2015. An integrated approach to delimiting species borders in the genus Chrysotoxum Meigen, 1803 (Diptera: Syrphidae), with description of two new species. Contributions to Zoology 84: 285–304.

Petanidou T., Vujić A. & Ellis W.N. 2011. Hoverfly diversity (Diptera: Syrphidae) in a Mediterranean scrub community near Athens, Greece. Annales de la Société entomologique de France 47: 168–175.

Quezada-Euan J.J.G., Sheets H.D., De Luna E. & Eltz T. 2015. Identification of cryptic species and morphotypes in male Euglossa: morphometric analysis of forewings (Hymenoptera: Euglossini). Apidologie 46: 787–795.

Radenković S., Šašić Zorić Lj., Djan M., Obreht Vidaković D., Ačanski J., Ståhls G., Veličković N., Markov Z., Petanidou T., Kočiš Tubić N. & Vujić A. 2018a. Cryptic speciation in the Merodon luteomaculatus complex (Diptera: Syrphidae) from the eastern Mediterranean. Journal of Zoological Systematics and Evolutionary Research 56 (2): 170–191.

Radenković S., Veličković N., Ssymank A., Obreht Vidaković D., Djan M., Ståhls G., Veselić S. & Vujić A. 2018b. Close relatives of Mediterranean endemo-relict hoverflies (Diptera, Syrphidae) in South Africa: morphological and molecular evidence in the Merodon melanocerus subgroup. PLoS One 13 (7): e0200805.

Radenković S., Vujić A., Vidaković D.O., Djan M., Milić D., Veselić S., Ståhls G. & Petanidou T. 2020. Sky island diversification in the Merodon rufus group (Diptera, Syrphidae) — recent vicariance in south-east Europe. Organisms Diversity & Evolution 20 (3): 345–368.

Ramage T., Charlat S. & Mengual X. 2018. Flower flies (Diptera, Syrphidae) of French Polynesia, with the description of two new species. European Journal of Taxonomy 448: 1–37.

Rego C., Smit J., Aguiar A., Cravo D., Penado A. & Boieiro M. 2022. A pictorial key for identification of the hoverflies (Diptera: Syrphidae) of the Madeira Archipelago. Biodiversity Data Journal 10: e78518.

Rohlf F.J. 2017. tpsDig program: digitize coordinates of landmarks and capture outlines, ver. 2.31. Department of Ecology and Evolution, State University of New York, Stony Brook, NY.

Šašić Lj., Ačanski J., Vujić A., Ståhls G., Radenković S., Milić D., Obreht Vidaković D. & Đan M. 2016. Molecular and morphological inference of three cryptic species within the Merodon aureus species group (Diptera: Syrphidae). PloS One 11 (8): e0160001.

Šašić Zorić Lj., Ačanski J.M., Đan M.R., Kočiš-Tubić N.S., Veličković N.N., Radenković S.R. & Vujić A.A. 2018. Integrative taxonomy of Merodon caerulescens complex (Diptera: Syrphidae)-evidence of cryptic speciation. Zbornik Matice srpske za prirodne nauke 135: 103–118.

Šašić Zorić Lj., Ačanski J., Vujić A., Ståhls G., Djan M. & Radenković S. 2020. Resolving the taxonomy of the Merodon dobrogensis species subgroup (Diptera: Syrphidae), with the description of a new species. The Canadian Entomologist 152 (1): 36–59.

Sauer F.G., Jaworski L., Erdbeer L., Heitmann A., Schmidt-Chanasit J., Kiel E. & Lühken R. 2020. Geometric morphometric wing analysis represents a robust tool to identify female mosquitoes (Diptera: Culicidae) in Germany. Scientific Reports 10: 17613.

Sheets H.D. 2012. IMP software series. Canisius College, Buffalo, New York.

Speight M.C.D. 1987. External morphology of adult Syrphidae (Diptera). Tijdschrift voor Entomologie 130: 141–175. Available from [accessed 24 Nov. 2023].

Speight M.C.D. 2020. StN Key for the Identification of the Genera of European Syrphidae (Diptera) 2020. Syrph the Net, the Database of European Syrphidae, Vol. 105, Syrph the Net publications, Dublin.

Speight M.C.D. & Sarthou J.P. 2017. StN Keys for the Identification of the European Species of various Genera of Syrphidae. Syrph the Net, the Database of European Syrphidae (Diptera). Vol. 99, Syrph the Net publications, Dublin.

Tatsuta H., Takahashi K.H. & Sakamaki Y. 2018. Geometric morphometrics in entomology: basics and applications. Entomological Science 21 (2): 164–184.

Thompson F.C. & Skevington J.H. 2014. Afrotropical flower flies (Diptera: Syrphidae). A new genus and species from Kenya, with a review of the melanostomine group of genera. Zootaxa 3847 (1): 97–114.

Thompson F.C., Mengual X., Young A.D. & Skevington J.H. 2017. Flower flies (Diptera: Syrphidae) of Philippines, Solomon Islands, Wallacea and New Guinea. Biodiversity, Biogeography and Nature Conservation in Wallacea and New Guinea 3: 501–524.

TIBCO Statistica. Available from,to%20the%20discrimination%20between%20groups [accessed 24 Nov. 2023].

Tot T. 2021. Taksonomija i Distribucija Tribusa Paragini Goffe, 1952 (Diptera: Syrphidae). PhD thesis, University of Novi Sad, Serbia.

Veselić S., Vujić A. & Radenković S. 2017. Three new Eastern-Mediterranean endemic species of the Merodon aureus group (Diptera: Syrphi-dae). Zootaxa 4254: 401–434.

Vujić A., Ståhls G., Ačanski J., Bartsch H., Bygebjerg R. & Stefanović A. 2013. Systematics of Pipizini and taxonomy of European Pipiza Fallén: molecular and morphological evidence (Diptera, Syrphidae). Zoologica Scripta 42 (3): 288–305.

Vujić A., Radenković S. & Likov L. 2018. Revision of the Palaearctic species of the Merodon desuturinus group (Diptera, Syrphidae). ZooKeys 771: 105–138.

Vujić A., Radenković S., Likov L., Andrić A., Gilasian E. & Barkalov A. 2019. Two new enigmatic species of the genus Merodon Meigen (Diptera: Syrphidae) from the north-eastern Middle East. Zootaxa 4555 (2): 187–208.

Vujić A., Radenković S., Likov L., Andrić A., Janković M., Ačanski J., Popov G., de Courcy Williams M., Šašić Zorić Lj. & Djan M. 2020a. Conflict and congruence between morphological and molecular data: revision of the Merodon constans group (Diptera: Syrphidae). Invertebrate Systematics 34: 406–448.

Vujić A., Likov L., Radenković S., Kočiš Tubić N., Djan M., Šebić A., Pérez-Bañón C., Barkalov A., Hayat R., Rojo S., Andrić A. & Ståhls G. 2020b. Revision of the Merodon serrulatus group (Diptera, Syrphidae). ZooKeys 909: 79–158.

Vujić A., Šašić Zorić Lj., Ačanski J., Likov L., Radenković S., Đan M. Milić D., Šebić A., Ranković M., Khaghaninia S. 2020c. Hide-and-seek with hoverflies: Merodon aureus – a species, a complex or a subgroup? Zoological Journal of the Linnean Society 190 (3): 974–1001.

Vujić A., Radenković S., Likov L. & Veselić S. 2021a. Taxonomic complexity in the genus Merodon Meigen, 1803 (Diptera, Syrphidae). ZooKeys 1031: 85–124.

Vujić A., Likov L., Popov S., Radenković S. & Hauser M. 2021b. Revision of the Merodon aurifer group (Diptera: Syrphidae) with new synonyms of M. testaceus Sack, 1913. Journal of Asia-Pacific Entomology 24 (4): 1301–1312.

Vujić A., Tot T., Andrić A., Ačanski J., Šašić Zorić Lj., Pérez-Bañón C., Aracil A., Veselić S., Arok M., Mengual Sanchís X. & van Eck A. 2021c. Review of the Merodon natans group with description of a new species, a key to the adults of known species of the natans lineage and first descriptions of some preimaginal stages. Arthropod Systematics & Phylogeny 79: 343–378.

Vujić A., Radenković S., Likov L., Gorše I., Djan M., Markov Ristić Z. & Barkalov A. 2022. Three new species of the Merodon ruficornis group (Diptera: Syrphidae) discovered at the edge of its range. Zootoxa 5182 (4): 301–347.

Zelditch M.L., Swiderski D.L., Sheets H.D. & Fink W.L. 2004. Geometric Morphometrics for Biologists: A Primer. Elsevier Academic Press, London.

How to Cite
Ačanski, J., Tot, T., Grković, A., Miličić, M., Radenković, S., & Vujić, A. (2023). An assessment of new character in hoverfly species delimitation using linear and geometric morphometrics – genus Merodon Meigen, 1803 (Diptera: Syrphidae) as a case study. European Journal of Taxonomy, 910(1), 98–114.
Research article