The Extraordinary Diversity of Merodon avidus Complex (Diptera: Syrphidae)-Adding New Areas, New Species and a New Molecular Marker

Abstract

In this paper, the Merodon avidus (Diptera, Syrphidae) species complex was revised, whereupon we discovered and described four new species for science: Merodon atroavidus Vujić, Radenković et Likov sp. nov., M. magnus Vujić, Kočiš Tubić et Ačanski sp. nov., M. nigroscutum Vujić, Radenković et Likov sp. nov. and M. pseudomoenium Vujić, Kočiš Tubić et Ačanski sp. nov. An integrative taxonomy approach was used to delimit species boundaries. Two molecular markers (the mitochondrial COI gene and nuclear 28S rRNA gene-newly analysed marker for the complex) and geometric morphometry of the wing shape, together with morphological data and distribution, successfully separated all species from the complex. The morphological variability of the analysed species is described and discussed and an illustrated diagnostic key for typical morpho-forms of species from the M. avidus complex is presented. A distribution map of all investigated species from the complex is provided. The level of endemicity of the M. avidus complex was discussed.

Keywords: 28S rRNA gene; COI gene; distribution; hoverflies; taxonomy; wing shape.

Figure 3

Maximum Likelihood tree based on the concatenated COI gene fragments (5′-end and 3′-end) (bootstrap support values (≥50) are shown near nodes).

Figure 4

Maximum Likelihood tree based on combined COI gene fragments (5′-end and 3′-end) and 28S rRNA gene sequences (bootstrap support values (≥50) are shown near nodes).

Figure 12

Basoflagellomere of male, lateral view. (a) M. atroavidus, (b) M. magnus and (c) M. nigroscutum (scale bar 0.5 mm).

Figure 13

Merodon magnus, head of male. (a) frontal view, (b) lateral view (scale bar 0.5 mm).

Figure 20

Metaleg, lateral view. (a,b) Merodon avidus, (c,d) M. megavidus ((a,c) male; (b,d) female; scale bar 1 mm).

Figure 1

Habitus of male (a) Merodon avidus and (b) M. moenium, dorsal view. Scale bar 2 mm.

Figure 2

Merodon moenium, the location of 11 landmarks on a left wing selected for geometric morphometric analysis.

Figure 5

Geometric morphometric analysis of the wing shape in males. (A) Position of male specimens in the space defined by CV1 and CV2 axes, (B) position of male specimens in the space defined by CV3 and CV4 axes, (C) position of male specimens in the space defined by CV5 and CV6 axes, (D) UPGMA phenogram constructed using squared Mahalanobis distances of wing shape.

Figure 6

Geometric morphometric analysis of the wing shape in females. (A) Position of female specimens in the space defined by CV1 and CV2 axes, (B) position of female specimens in the space defined by CV3 and CV4 axes, (C) position of female specimens in the space defined by CV4 and CV5 axes, (D) UPGMA phenogram constructed using squared Mahalanobis distances of wing shape.

Figure 7

UPGMA phenogram constructed using squared Mahalanobis distances of wing shape for populations of species of the Merodon avidus complex.

Figure 8

Legs of male. (a) Merodon atroavidus, (b) M. nigroscutum, (c) M. magnus, (d) M. pseudomoenium and (e,f) M. atroavidus. (a–d) metaleg, lateral view, (e) protibia and –tarsus, dorsal view and (f) mesotibia and –tarsus, dorsal view (scale bar (a–d) 1 mm, (e,f) 0.5 mm).

Figure 9

Metatarsus of male, dorsal view. (a) Merodon avidus, (b) M. femoratus, (c) M. nigritarsis, (d) M. atroavidus and (e,f) M. megavidus (scale bar (a–d) 0.5 mm, (e,f) 0.75 mm).

Figure 10

Male genitalia Merodon avidus. (a) epandrium, lateral view, (b) epandrium, ventral view and (c) hypandrium, lateral view (scale bar 0.2 mm). pl—posterior surstylar lobe; al—anterior surstylar lobe; s—lateral sclerite of aedeagus; the ctenidium marked with arrow.

Figure 11

Male genitalia Merodon nigritarsis.(a) epandrium, lateral view, (b) epandrium, ventral view and (c) hypandrium, lateral view (scale bar 0.5 mm). pl—posterior surstylar lobe; al—anterior surstylar lobe; s—lateral sclerite of aedeagus; the subapical thorn marked with arrow.

Figure 14

Abdomen of male, dorsal view. (a) M. atroavidus, (b) M. magnus, (c) M. nigroscutum and (d) M. pseudomoenium (scale bar 1 mm).

Figure 15

Abdomen of female, dorsal view. (a) M. atroavidus, (b) M. nigroscutum (scale bar 1 mm).

Figure 16

Thorax of female, lateral view. (a) M. atroavidus, (b) M. nigroscutum (scale bar 1 mm).

Figure 17

Male genitalia, surstylar lobe, lateral view. (a) M. atroavidus, (b) M. magnus, (c) M. nigroscutum and (d) M. pseudomoenium (scale bar 0.1 mm). pl—posterior surstylar lobe; al—anterior surstylar lobe.

Figure 18

Distribution map of M. avidus, M. ibericus, M. atroavidus sp. nov and M. nigroscutum sp. nov.

Figure 19

Distribution map of M. megavidus, M. moenium, M. magnus sp. nov and M. pseudomoenium sp. nov.

Figure 21

Summary of the results of integrative species delimitation. Each species is represented by a different colour. Solid colour boxes indicate successful species delimitation by a particular approach. Multicolour boxes depict clusters formed by multiple species.