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Immature stages of Microdon myrmicae Egg Figs 1, 11 Width = 587.4 �� 36.61 ��m; length = 1.08 �� 0.03 mm (n = 10). First instar larva Figs 2���6, 11, Supplementary Material 1 Body width = 679.5 �� 55.42 ��m; body length = 0.996 �� 0.08 mm (n = 10). Body features. Body with regularly rounded sides. Four longitudinal grooves present dorsally (Fig. 2A) dividing dorsal body surface into five main longitudinal fields: one medial, two lateral and two external fields. Medial field partially divided into two halves by a longitudinal, medial line. Dorsal surface with regularly spaced ���flower-like��� sensilla (Figs 3A, E): medial field with two longitudinal rows of nine sensilla; each lateral field with 13 sensilla arranged in two rows (seven along lateral groove and six along medial groove); each external field with one row of 10 sensilla. Each sensillum (Fig. 3E) composed of a cylindrical base, with many imbricate, thick sculpticels, apically with a medial flower-like structure with a variable number (5���10) of long lobes, pointed at tip, encircling a medial dome. Ventral surface covered medially by pointed microsculpture, finely pilose on sides. Ventral flower-like sensilla (Figs 3C, G) similar to dorsal ones except for flat, soft, unsculptured base and flat, thin, distinctly pointed lobes. Pseudocephalon. Two pairs of sensorial organs on dorsal surface of pseudocephalon (Figs 4E, G), one anterior (Fig. 4E) and one posterior (Fig. 4G), each composed of clusters of four short and one long trichoid sensilla emerging from bulbous, hollow base. Posterior spiracular tubercle. Impair respiratory structure, elongated in shape; surface of spiracular tubercle with peculiar microsculpture, completely covered by imbricate, sclerotised scales with an irregularly indented apex (Fig. 5A). Apex of tubercle with two circular smooth plates, slightly convex (Fig. 5C). Marginal band. Distinctly long fringe, length of processes regularly varying, showing eight waves on each side (Figs 2A, E, 6A, C, E). Each individual process composed of an elongate stem and an apical fringed brush (Figs 6A, C, E); the stem showing two very different surfaces: dorsal surface apparently articulated with 4���5 imbricated joints, the distal one fringed apically (Figs 6A, E); ventral surface completely smooth (Fig. 6C). Third instar larva Figs 7���9, 11 Body width = 4.5 �� 0.7 mm; body length = 6.1 �� 0.8 mm (n = 10). Dorsal reticulation. Dorsal reticulation reduced to a narrow, lateral belt around the perimeter of abdomen (Figs 7A, B). Each reticulation process showing sub circular groups of 5���9 umbrella-like structures with a flattened, circular apex (Figs 7A, B). Posterior spiracular tubercle. Dome shaped with two round holes spaced 1.2 times as long as their diameter; apex divided into two halves (Figs 8A, B) by a narrow furrow showing irregular plates. Marginal band. Processes on the marginal band short and thick, set close to one another, parallel, radially projecting, with suboval basal ���joints���, not imbricated, the last one produced into a flat medial brush. Processes on the marginal band of three types (Figs 9A, B): type one basally 4���jointed and apically single and flat, with medial brush 2���lobed; type two basally 3���jointed and apically bifurcate, with medial brush 1���lobed; type three basally 3���jointed and apically produced into a group of three spiniform setae. Type one and type two regularly alternating in sequence, type three irregularly present between two type one processes. Puparium Figs 10, 11 Body width = 6.1 �� 0.5 mm; body length = 7.9 �� 0.7 mm (n = 10). Anterior spiracular tubercles. Length of each tubercle about 1.4 times as long as wide, conical, tapering at the apex (Fig. 10A, B), smooth at the base, with the apex furrowed by about 150 respiratory fissures (Figs 10A); each fissure laying on a small papilla (Fig. 10B)., Published as part of 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, pp. 348-370 in Zootaxa 4789 (2) on pages 354-357, DOI: 10.11646/zootaxa.4789.2.2, http://zenodo.org/record/3990836

Immature stages of Microdon devius Third instar larva Figs 7���9 Body width = 7.2 �� 0.6 mm; body length = 9.4 �� 0.9 mm (n = 10). Dorsal reticulation. Dorsal reticulation extended over the whole dorsal body surface. Each process resembling a sea anemone, being divided into a smooth, columnar trunk topped by a brush composed by 20���30 long, flexible filaments (Fig. 7F). Posterior spiracular tubercle. Longer than wide, subquadrate in dorsal view, concave medially, bulged sub���basally; distance between spiracular holes 1.8 times as long as their diameter (Figs 8E, F). The base of posterior spiracular tubercle encircled by a smooth cuticular crown (Figs 8E, F). Spiracular plates flattened to slightly concave, of variable shape, separated by a broad and deep midsagittal cleft. Marginal band. Processes on the marginal band apparently without basal articulated joints (Figs 9E, F). Processes on the marginal band of three types: type one long and single, apically fringed; type two short and bifurcate, apically 2���lobed; type three composed by two type one flanking a cluster of three spiniform setae (Figs 9E, F). Puparium Figs 10, 11 Body width = 7.3 �� 0.4 mm; body length = 9.7 �� 0.5 mm (n = 10). Anterior spiracular tubercles. Length of each tubercle 2.25 times as long as wide and strongly curved (Fig. 11F), subcylindrical, slender, somewhat pointed at the apex, entirely furrowed by about 180 respiratory fissures (Figs 10E, F). Each fissure laying on a small papilla (Fig. 10F)., Published as part of 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, pp. 348-370 in Zootaxa 4789 (2) on pages 360-362, DOI: 10.11646/zootaxa.4789.2.2, http://zenodo.org/record/3990836

Keys to immature stages of the European species of Microdon First instar larvae 1 Body about 1.5 times as long as wide; posterior spiracular tubercle long (more than 1.5 times as long as wide at base); marginal band elongate, showing eight waves on each side...................................... M. myrmicae / M. mutabilis - Body about two times as long as wide; posterior spiracular tubercle very short (wider than long at base); marginal band short, showing 10 waves on each side................................................................... M. analis Puparia 1 Most of the dorsal surface of puparium smooth and bare, with reticulation reduced to a narrow, lateral belt.............. 2 - Dorsal surface of puparium completely covered by a dorsal reticulation.......................................... 3 2 Anterior spiracular tubercles conical, tapering at apex; anterior spiracular tubercles about 1.4 times as long as wide at base; each reticulation process composed of groups of umbrella-like structures................................... M. myrmicae - Anterior spiracular tubercles dome-shaped, blunt at apex; anterior spiracular tubercles about 0.8 times as long as wide at base; each reticulation process composed of stringy, extended projections.................................... M. mutabilis 3 Meshes of the dorsal reticulation no broader than the basal diameter of the posterior spiracular tubercle; posterior spiracular tubercle wider than long; anterior spiracular tubercles straight................................................. 4 - Meshes of the dorsal reticulation two times as broad as the basal diameter of the posterior spiracular tubercle; posterior spiracular tubercle longer than wide; anterior spilacural tubercles laterally curved................................. M. devius 4 Anterior spiracular tubercles equal or more than two times as long as wide....................................... 5 - Anterior spiracular tubercles one time only as long as wide, or shorter than wide.............................. M. miki 5 Anterior spiracular tubercles nearly cylindrical, about three times as long as wide; posterior spiracular tubercle light-brown contrasting with the reddish-brown apical spiracular plates.............................................. M. analis - Anterior spiracular tubercles clearly conical, about two times as long as wide; posterior spiracular tubercle uniformly reddishbrown....................................................................................... M. major, Published as part of 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, pp. 348-370 in Zootaxa 4789 (2) on pages 364-365, DOI: 10.11646/zootaxa.4789.2.2, http://zenodo.org/record/3990836

Immature stages of Microdon analis Egg Fig. 1 Width = 450.71 �� 52.89 ��m; length = 897.41 �� 59.72 ��m (n = 10). First instar larva Figs 2���6, Supplementary Material 2 Body width = 456.23 �� 29.41 ��m; body length = 900.77 �� 75.14 ��m (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)., Published as part of 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, pp. 348-370 in Zootaxa 4789 (2) on pages 358-360, DOI: 10.11646/zootaxa.4789.2.2, http://zenodo.org/record/3990836

Ant nest beetles (Carabidae, Paussinae, Paussini; Paussus) are renowned myrmecophiles, mostly known for their bizarre and diverse antennal shape. While little is known about their development, behavior and host range, we do know they spend most of their lives inside ant nests, feeding upon the hemolymph of ant brood and teneral workers. Recent findings suggest these beetles use a surprisingly complex strategy for interacting and deceiving ants. They have managed to break into multiple communication channels that ants use to recognize and communicate with one another in order to deceive the ants and profit from the rich resources of the nest. Mounting evidence from structural, chemical, acoustic, and behavioral studies support the hypothesis that Paussus is among the most highly integrated parasite of social insects known to date.

The myrmecophilous immature stages of hover fl ies of the genus Microdon Meigen, 1803 (Diptera, Syrphidae) are still poorly known and only about 15 species were previously incompletely described and/or illustrated using light microscopy based on occasional fi ndings mainly of pupae and third instar larvae. The exceptional fi nding of a large number of second and third instar larvae and pupae (159 specimens) of Microdon mutabilis (Linnaeus, 1758) inside the nest of a new host species, Formica cunicularia Latreille,1798, enabled us to rear them and obtain a great number of eggs and fi rst instar larvae. We fi lmed and described the feeding behaviour and locomotion of these highly derived slug-like larvae. Combining light, fl uorescence and scanning electron (SEM) microscopy, we describe in detail and illustrate the external features of all the immature stages of M. mutabilis (eggs, larvae and pupae). Covering the entire chorion of the egg is a peculiar microsculpture composed of volcano-like processes. The three larval instars strongly differ from each other, especially at the level of the shape of the body, the posterior spiracular tubercle and the cephaloskeleton. SEM microscopy was used to describe in detail the microsculpture, sensorial structures, spiracles and cephalic appendages of larvae and pupae. Fluorescence microscopy was used to reveal the exceptional presence of resilin in the external layer of the posterior spiracular tubercle in fi rst instar larvae. The possible functional signifi cance of these structures is discussed.

A case of copulation between two mimic and repellent beetle species (a male of Timarcha fracassii, and a female of Meloe autumnalis), belonging to distinct families (Chrysomelidae, Meloidae), is recorded., Fragmenta Entomologica, Vol. 49 No. 2 (2017)