Microdon analis (Macquart, 1842)

Scarparo, Giulia, Wolton, Robert, Molfini, Marco, Pinna, Luigi Cao & Ulio, Andrea Di Gi-, 2020, Comparative morphology of myrmecophilous immature stages of European Microdon species (Diptera: Syrphidae): updated identification key and new diagnostic characters, Zootaxa 4789 (2), pp. 348-370 : 358-360

Immature stages of Microdon analis

Egg

Fig. 1

Width = 450.71 ± 52.89 µm; length = 897.41 ± 59.72 µm (n = 10).

First instar larva

Figs 2−6 , Supplementary Material 2

Body width = 456.23 ± 29.41 µm; body length = 900.77 ± 75.14 µm (n = 10). Body features. Body rounded anteriorly and posteriorly, but subparallel on sides. Two longitudinal grooves present dorsally ( Fig. 2B ), dividing dorsal body surface into three main longitudinal fields: one medial, two external marginal fields. Dorsal surface adorned with raised sculpture and showing 62 regularly spaced flower-like sensilla ( Fig. 3B ) distributed as follows: medial field with two longitudinal rows of nine sensilla; each marginal field with 22 sensilla. Each flower-like sensillum ( Fig. 3F ) composed of a long cylindrical base, apically with a medial flower-like structure with a variable number (6−7) of short lobes not exceeding the diameter of the base. Ventral surface without hairy microsculpture, showing transverse twisted protuberances ( Fig. 3D ). Ventral flower-like sensilla ( Fig. 3H ) dome-shaped, with an unsculptured simple base, without radial lobes. Pseudocephalon. Distal segment of the antenna distinctly narrowed at the apex ( Figs 4B, D ). Posterior sensorial organs on dorsal surface of pseudocephalon composed three short trichoid sensilla emerging from bulbous base ( Fig. 4H ). Posterior spiracular tubercle. Impair structure, short, bilobed. Surface of spiracular tubercle with microsculpture composed by thick, pointed, slightly imbricated scales ( Figs 5B, D, F ). Apex with depressed plates, laterally produced into four spikes: posterior spikes longer than the anterior ( Figs 5D, F ). Marginal band. Distinctly short fringe, showing 10 waves on each side ( Figs 6B, D, F ). Each simple process smooth both dorsally and ventrally ( Figs 6B, D, F ).

Third instar larva

Figs 7–9

Body width = 6.41 ± 0.64 mm; body length = 8.25 ± 0.54 mm (n = 10). Dorsal reticulation. Dorsal reticulation extended over the whole dorsal body surface. Each process divided into a dome-shaped basal disk supporting a branched spine ( Figs 7C, D ). Spines 2–branched not articulating with disk; processes disposed in 1–2 rows; trumpet-shaped tubercles ( Fig. 7D ) in 2–3 concentric circles on basal disk around spine base; dorsal spine branches intertwined extensively with branches originating 3–4 spines away. Dorsal flower-like sensilla with cylindrical smooth base and 3–4 lobes radiating from apex, lacking the central dome ( Fig. 7D ), always present at intersections of process rows and extending well above spines; each sensillum 4–5 times height of undivided spine base, 2–3 times length of processes. Posterior spiracular tubercle. Slightly wider than long structure, subrectangular both in dorsal and anterior views, concave medially ( Figs 8C, D ), with two round holes spaced 1.2 times as long as their diameter. Base of posterior spiracular tubercle encircled by a smooth cuticular crown. Spiracular plates flattened to slightly convex, of variable shape, separated by a broad and deep midsagittal cleft ( Figs 8C, D ). Marginal band. Processes on the marginal band apparently without basal articulated joints ( Figs 9C, D ).

Puparium

Figs 10 , 11

Body width = 7.4 ± 0.4 mm; body length = 9.2 ± 0.3 mm (n = 10). Anterior spiracular tubercles. Length of each tubercle about three times as long as wide, subcylindrical, with sides entirely and strongly wrinkled, blunt at the apex, with the apex furrowed by about 30 respiratory fissures ( Figs 10C, D ). Each fissure laying on a small papilla ( Fig. 10D ).

Figures

FIGURE 1. Egg of M. myrmicae (A, C, E) and M.analis (B, D, F): A, B—lateral view; C, D—detail of anterior pole with micropyle area. E, F—chorion microsculpture of volcano-like processes. A, B = 500 µm; C = 100 µm; D, E = 50 µm; F = 40 µm. ASl, alveolate slope; Cr, crater; MA, micropyle area; RP, radial projection; VP, volcano-like process.

FIGURE 2. First instar larvae of M. myrmicae (A, C, E) and M. analis (B, D, F): A, B—dorsal view; C, D—lateral view; E, F—ventral view.A–F = 500 µm. AO, anal opening; LLb, lateral lobe; MrB, marginal band; MG, medial groove; MrS, marginal stripe; PC, pseudocephalon; PSprTu, posterior spiracular tubercle; VLb, venteral lobe; WMrB, waves of marginal band.

FIGURE 3. Details of first instar larvae of M. myrmicae (A, C, E, G) and M. analis (B, D, F, H): A, B—dorsal microsculpture; C, D—ventral microsculpture; E, F—dorsal flower–like sensilla; G, H—ventral flower like sensilla.A, B, C, D = 100 µm; E, F, G = 10 µm; H = 30 µm. FS, flower-like sensilla.

FIGURE 4. Pseudocephalon of first instar larvae of M. myrmicae (A, C, E, G) and M. analis (B, D, F, H): A, B—dorsal view; C, D antennomaxillary lobes; E, F—anterior sensorial organs; G, H—posterior sensorial organs. A = 100 µm; B = 200 µm; C = 40 µm; D = 50 µm; E, F = 30 µm; G, H = 10 µm. Ant, antenna; Asn, anterior sensillum; MxPlp, maxillary palp; Psn, posterior sensillum.

FIGURE 5. Posterior spiracular tubercle of first instar larvae of M. myrmicae (A, C, E) and M. analis (B, D, F): A, B—anterior view; C, D—apical view; E, F—lateral view. A, C = 100 µm; B–, D= 50 µm E = 200 µm. ReFis, respiratory fissures; SprPlt, spiracular plate.

FIGURE 6. Marginal band of first instar larvae of M. myrmicae (A, C, E) and M. analis (B, D, F): A, B—dorsal view; C, D—ventral view; E, F—detail of processes, dorsal view.A = 100 µm; B, C, D = 50 µm; E = 40 µm; F = 20 µm. FS, flower–like sensilla; IJ, imbricate joint; SpS, spiniform setae; WMrB, waves of marginal band.

FIGURE 7. Dorsal reticulation of third instar larvae of M. myrmicae (A, B), M. analis (C, D) and M. devius (E, F); left, general view; right, detail of single reticulation processes. A = 400 µm; B = 50 µm; C, E = 500 µm; D = 100 µm; F = 200 µm.

FIGURE 8. Posterior spiracular tubercle of third instar larvae of M. myrmicae (A, B), M. analis(C, D), M. devius (E, F) and M. mutabilis (G, H); left, anterior view; right, apical view. A–H = 500 µm. ReFis, respiratory fissures; RH, respiratory hole; SC, smooth crown.

FIGURE 9. Marginal band of third instar larvae of M. myrmicae (A, B), M. analis (C, D) and M. devius (E, F); left, dorsal view; right, detail of marginal band. A = 500 µm; B, E = 300 µm; C = 100 µm; D = 50 µm; F = 200 µm.

FIGURE 10. Anterior spiracular tubercles of puparia of M. myrmicae (A, B), M. analis(C, D), M. devius (E, F) and M. mutabilis (G, H); left, lateral view; right, detail of respiratory fissures. A, E, G = 500 µm; B, F, H = 100 µm; C = 400 µm; D = 50 µm. ReFis, respiratory fissures.

FIGURE 11. Eggs of M. myrmicae trapping small drops of water (pointed with red arrows) with their volcano-like processes (A); third instar M. myrmicae larvae with larvae and workers of Myrmica scabrinodis (B); third instar larva and first instar larva (red arrow) of M. myrmicae with M. scabrinodis larvae, ventral view (C); M. myrmicae adult emerging from puparium, anterior view (D); two M. analis pupae and a puparium (E); M. devius pupa (F).