Insects of Britain and Ireland: the genera of Syrphidae (hoverflies)

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L. Watson and M. J. Dallwitz

Ferdinandea Rondani

Chrysoclamis Rondani, Chrysochlamys.

Adult flies. The flies commonly sitting on bark, somewhat resembling a mining bee (cf. Andrena apicata), or megachilid bee-like (cf. Osmia rufa), or muscid-like (!); with greyish thorax and greenish to brassy or bluish-black abdomen; small to medium sized; 10–13 mm long. Wings 6.25–11.25 mm long.

The head wider than the thorax. The face flat or concave in the region between the antennae and the mouth; without a central knob. The eyes depicted as finely hairy; rimmed along their facial borders for much of the height of the face (cf. Cheilosia). Antennae relatively short, drooping; with their bases approximated; black and red. The third antennal segment ovoid or orbicular. The antennal bristle dorsal; much longer than the third segment; simple (bare).

The humeri hairy, and readily visible behind the head. The thorax pubescent with stiff bristles interspersed; patterned; with longitudinal stripes (these greyish). The scutellum somewhat convex, with undefined edge; brownish, ferrugineous or tawny, or black (greyish tawny, according to Walker). Wings patterned (pale grey, slightly tawny along the fore border, and with brown spots along the two transverse disc veinlets); without a conspicuously dark stigma; divergent in repose. Wing veins R2+3 and R4+5 not forming a closed cell. The anterior cross vein R-M in cell R5 crossing it before the middle of the adjoining discal cell, or crossing it at or beyond the middle of the adjoining discal cell (near the middle). Vein R4+5 without a conspicuous curve projecting into the cell R5; without a backwardly projecting, incomplete transverse veinlet. Vein R bearing bristles. The lower outer marginal vein slightly diverging from the posterior wing margin to more or less parallel with the posterior wing margin. The upper and lower outer marginal cross veins slightly stepped. The upper outer marginal cross-vein conspicuously bent near the base the base; not re-entrant.

The abdomen wider than the thorax; oval, or oblong. The male abdomen with 4 visible segments. The abdomen not contrastingly patterned. The spiracles of the third abdominal segment borne at or near the anterior corner of each side.

Larvae and pupae. The larvae somewhat broader posteriorly, tapered to the head; posteriorly blunt and tail-less; flattened (prolegs absent); brownish, plain; without thoracic hooks; mouth without triangular sclerites; anal segments with lappets (the anal segment with three pairs, these equal-sized). The larvae saprophagous; in sap runs and in decaying sap under loose bark (on deciduous trees, especially associated with Cossus borings).

Classification. Subfamily Milesiinae; tribe Cheilosiini.

British representation. 2 species in Britain.

Illustrations. • F. cuprea, female (with Caliprobola, Leucozona and Mallota). • F. cuprea, details of wing and thorax: Verrall. • 18 genera (from Walker).

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the genera of Syrphidae (hoverflies). Version: 28th July 2015.’.