Merodon avidus (Rossi)

Preradović, Jelena, Andrić, Andrijana, Radenković, Snežana, Zorić, Ljiljana Šašić, Pérez-Bañón, Celeste, Campoy, Andrés & Vujić, Ante, 2018, Pupal stages of three species of the phytophagous genus Merodon Meigen (Diptera: Syrphidae), Zootaxa 4420 (2), pp. 229-242 : 233-234

Merodon avidus (Rossi)

Puparium description. Dimensions and shape. Length: 9.7 mm, width: 4.7 mm, height: 4.7 mm (n=2); subcylindrical; anterior end truncate, slightly tapering posteriorly and flattened Ventrally; dark brown in colour; rough integument with larVal segmentation persisting as transVerse folds and wrinkles.

Cephalopharyngeal skeleton (n=3). Mandibles with black sclerotised hooks and blunt apex, without accessory teeth, fused to the external mandibular lobes; the mouth hooks separated at the apex by a distance wider than or equal as their basal width; the dorsal cornu tapered towards the apex, shark’s fin shaped, representing two thirds of the whole length of the Ventral cornu; clipeal sclerite and tentorium slightly sclerotised and separated from the highly sclerotised intermediate sclerites; Ventral cornu elongated and narrow in profile View, with the cibarium at the base ( Fig. 1B ).

Pupal spiracles. Sclerotised, blackish-brown in colour, stout, cylindrical in shape, gradually tapering and pointed at the end; length ≈ 0.4 mm (length: width ratio of spiracle 1.5:1); separated by a distance of 4× their length; surface of the spiracle with a polygonal pattern ( Fig. 2C ); dorsal surface facing toward the lateral margins of the puparium and with the distal one-fifth slightly curVed backwards; about 60% of the dorsal and lateral surface coVered with irregularly-spaced, oVal-shaped tubercles; tubercle composed of two layers; 5–6 radially-arranged spiracular openings on each tubercle.

Prp. Blackish-brown, sub-elliptical in cross-section, extremely short (not Visible from dorsal View); spiracular plate of prp with four pairs of sinuous spiracular openings around two central scars ( Fig. 3D ); four pairs of interspiracular setae emerging from the edge of the spiracular plate.

Examined material. Đerdap National Park, Serbia (44° 32 ' 38"N, 22°01'08"E), leg. J. PreradoVić: 2 puparia in the ground near bulbs of Ornithogalum umbellatum, Viii.2015 and xi.2015 (P2 and P 5 in FSUNS); 1 puparium on the ground close to O. umbellatum plants, Viii.2015 (P 3 in FSUNS); 1 puparium in the ground near bulbs of O. umbellatum, 29.V.2016, ♂ emerged on 8.Vi. 2016 (P 6 in FSUNS).

Figures

FIGURE 1. Cephalopharyngeal skeleton of Merodon puparia, lateral view: (A) M. aureus (P4), (B) M. avidus (P2). Abbreviations: c, cibarium; cs, clipeal sclerite; dc, dorsal cornu; is, intermediate sclerite; m, mandibles; t, tentorium; vc, ventral cornu. Scale lines: A, B = 500 µm.

FIGURE 2. SEM micrographs of the pupal spiracles of Merodon puparia: (A) M. aureus (P4), (B) M. aureus (P1), (C) M. avidus (P6), (D) M. rufus; (A, C, D) Pupal spiracle, (B) Spiracular openings on a tubercle. Abbreviation: tu, tubercle. Scale lines: A, C = 200 µm; B = 5 µm; D = 50 µm.

FIGURE 3. SEM micrographs of the posterior respiratory processes (prp) of Merodon puparia: (A, B) M. aureus (P4), (C) M. aureus (P1), (D) M. avidus (P2), (E, F) M. rufus; (B, D, F) prp showing the spiracular plate, (A, E) prp in dorsal view, (C) Inter- spiracular seta. Abbreviations: cs, central scar; is, inter-spiracular seta; so, spiracular opening. Scale lines: A, D = 250 µm; B = 200 µm; C = 10 µm; E, F = 100 µm.