Conflict and congruence between morphological and molecular data: revision of the Merodon constans group (Diptera : Syrphidae)

Abstract

We revise the Merodon constans species group of the genus Merodon Meigen, 1803 (Diptera: Syrphidae), provide morphological diagnosesand descriptions, as well as an illustrated key and a discussion on the different taxonomic characters used. In total, 15 species were studied, their geographic distributions are presented on maps, and nine new species are described. Two species are redefined and neotypes are designated, lectotypes are designated for five species, and onespeciesis reinstated as valid. Following a detailed study of type material in different entomological collections, the status of several species is revised and three new synonymies are proposed. The M. constans species group was resolved as being monophyletic within the M. albifrons lineage based on molecular analyses using COI and 28S rRNA gene sequences. Three species morphologically similar to M. constans (Rossi, 1794) but occurring outside its distributional rangewere supported as being valid and distinct species on the basis of molecular data, but they were not distinguishable based on morphological characters. By contrast, continental populations of M. analis Meigen, 1822 could not be separated from Mediterranean M. constans based on differences in COI or 28S rRNA genes. The same molecular markers could not discriminate between two other species pairs. We conclude that these molecular markers only partially resolve species within the M. constans group. Geometric morphometry of wing shape successfully separated M. analis and M. constans, as well as M. spineus Vujić, Šašić Zorić & Likov, sp. nov. in both species and population analyses.

Merodon chalybeus Subgroup: An Additional Piece of the M. aureus Group (Diptera, Syrphidae) Puzzle

“…Here, we confirmed identifications made using wing shape by molecular findings which supports the results of some earlier taxonomic studies of cryptic hoverfly species (Nedeljković et al 2013, 2015, Ačanski et al 2016, Šašić et al 2016, Šašić Zorić et al 2020, Djan et al 2020, Vujić et al 2020a, 2021b.…”

“…It is distributed in the Palaearctic and Afrotropical Regions and comprises 199 species (Vujić et al 2021a(Vujić et al , 2021c(Vujić et al , 2021d. The number of species is still rising, and many new species have recently been described (Marcos-García et al 2011, Radenković et al 2011, 2018a, 2018b, 2020, 2015, 2020a, 2020b, Ačanski et al 2016, Šašić et al 2016, 2020, Djan et al 2020. Adults of Merodon morphologically mimic bumblebees and bees (Hymenoptera: Apidae) and feed on pollen and nectar from early spring to late autumn (Speight 2020).…”

“…High morphological similarity between M. chalybeus and M. minutus and their potentially overlapping distributions make their taxonomic status questionable and stresses the need for further material to be examined using multiple data sources, such as traditional morphology, molecular data, geometric morphometry and distributional data. Integrative taxonomic approach using data from different sources was proved to be useful in many recent studies on Merodon (e.g., Marcos-García et al 2011, Ačanski et al 2016, Šašić et al 2016, Radenković et al 2018a, 2018b, 2020, Arok et al 2019, Djan et al 2020, Vujić et al 2020a, 2020b. DNA barcoding of species based on analyses of the 5´-end of the COI gene has become standard practice in integrative taxonomy since its introduction by Hebert et al (2003).…”

Three new species of the Merodon ruficornis group (Diptera: Syrphidae) discovered at the edge of its range

“…Europe hosts 120 described species of the genus (Vujić et al 2021) with the highest species diversity in the Mediterranean Basin (Vujić et al 2012), which has been in linked to the high diversity of bulbous plant species that serve as larval host plants (Ricarte et al 2008(Ricarte et al , 2017Andrić et al 2014;Preradović et al 2018). Asia Minor and Eastern Europe (especially the Balkan Peninsula) are considered hotspots for the genus, harboring high endemism (Kaloveloni et al 2015), as documented by several studies in the Eastern Mediterranean Basin (Vujić et al 2007(Vujić et al , 2011(Vujić et al , 2013a(Vujić et al , 2015(Vujić et al , 2020aStåhls et al 2009Ståhls et al , 2016Radenković et al 2011Radenković et al , 2020Kaloveloni et al 2015;Ačanski et al 2016a, b;Likov et al 2020).…”

“…Molecular taxonomic studies of hoverflies using both the 3' and 5' ends of the mitochondrial cytochrome c oxidase subunit I (COI) gene have proven to be a powerful tool for species delimitation in various genera (Mengual et al 2006;Marcos-García et al 2011;Barkalov & Stĺhls 2015;Nedeljkoviă et al 2015;Chroni et al 2017;Nedeljković et al 2020). Integration of molecular analyses with traditional taxonomy in the Merodon genus has allowed to describe high diversity and the presence of closely-related or cryptic species (Ståhlset al 2009;Vujić et al 2012Vujić et al , 2013bŠašić et al 2016;Mengual et al 2018;Radenković et al 2018;Vujić et al 2020a;Zorić et al 2020;Vujić et al 2021a).…”