Myolepta difformis Strobl, 1909

Ricarte, Antonio, Marcos-García, M Angeles, Pérez-Bañón, Celeste & Rotheray, Graham E., 2007, The early stages and breeding sites of four rare saproxylic hoverflies (Diptera: Syrphidae) from Spain, Journal of Natural History 41 (25 - 28), pp. 1717-1730 : 1723-1725

Myolepta difformis Strobl

Puparium

Overall appearance. Short-tailed larva with mouthparts of the saprophagous type ( Rotheray and Gilbert 1999); sub-cylindrical in cross-section, truncate anteriorly, tapering posteriorly; prolegs bearing crochets present on mesothorax and first six abdominal segments; anal segment coated in papillae bearing tufts of setae; pupal spiracles club-tipped with basal sculpture of dome-shaped projections; prp narrow and yellow-brown.

Dimensions. Length 6.56 mm, range 6.17–6.83 mm; width 3.04 mm, range 2.64–3.36 (n 53).

Head skeleton ( Figure 9 ). Basal sclerite at junction of dorsal and ventral cornea only heavily sclerotized posteriorly; dorsal cornu rounded dorsally and posteriorly; ventral cornu bar-shaped, not inflated and about four times as long as dorsal cornu; parastomal bars bordering epipharyngeal plate not distinct; sclerotization lacking between dorsal bridge and tentorial bar; dorsal bridge and ventral pharyngeal ridges present; ventral bridge as wide as tentorial bar; mandibular sclerite T-shaped.

Prothorax. Anterior fold with setae not spicules.

Anterior spiracles ( Figure 14 ). Anterior spiracles 0.06 mm long, truncate apically, brown, with a pair of oval, spiracular openings at the apex.

Mesothorax. Prolegs present with two rows of crochets.

Abdomen. Vestiture varying in size from 0.03 to 0.12 mm, fine, pale brown setae, except on the ventral surface, where pubescence is inconspicuous; anal segment coated in papillae with tufts of setae at their tips; first and second pairs of lappets indistinct but third pair of lappets conspicuous, 0.28 mm long; prolegs with two rows of crochets present on the first six abdominal segments.

Pupal spiracles ( Figure 15 ). Separated by a distance twice their length, 0.46 mm long, yellow-brown in colour, club-tipped with irregularly spaced, rounded tubercles bearing three or four radially arranged spiracular openings on the enlarged apex; base sculptured with dome-shaped projections.

Posterior respiratory process ( Figure 16 ). Length 1.96 mm; width at transverse band 0.22 mm (n 53); smooth, without sculpturing, yellowish brown in colour, with an indistinct transverse band and each spiracular plate bearing three pairs of gently curved, spiracular openings, interspiracular setae consisting of three or four long and conspicuous setal branches and a pit between the dorsal and dorso-lateral interspiracular setae.

Material examined

One puparium from larva collected 23 March 2004, from a 1.3 m high hole containing standing water on a live F. angustifolia tree, Spain, Ciudad Real, Cabañeros National Park, Fresneda de Gargantilla, C. Pérez-Bañón and M. A. Marcos-García, puparium formed 3 May 2004, female emerged 19 May 2004; two puparia from larvae collected 19 March 2004, from a 2 m high hole with standing water from either a F. angustifolia or a Q. faginea tree, Spain, Ciudad Real, Cabañeros National Park, Canalejas valley, M. A. Marcos- García, G. Rotheray, and G. Hancock, puparia formed 1 April 2004 and females emerged 14–15 April 2000.

Figures

Figures 8, 9. Head skeletons in lateral view. (8) Mallota dusmeti. (9) Myolepta difformis. Scale bar: 1.2 mm.

Figures 14–17. Myolepta spp. SEMs. (14) M. difformis anterior spiracle. (15) M. difformis pupal spiracle in dorsal view. (16) M. difformis prp apical end showing laterally the spiracular plate and setae (notice the white patches, always coating extensively Myolepta species puparia). (17) M. obscura prp showing remains of the typical Myolepta white coating (dorsal view). Scale and other photo data are shown at the bottom of each figure.