Rhagonycha translucida (Krynicky, 1832)

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POLYPHAGA Emery, 1886

ELATEROIDEA Leach, 1815

CANTHARIDAE Imhoff, 1856

CANTHARINAE Imhoff, 1856

CANTHARINI Imhoff, 1856

Rhagonycha Eschscholtz, 1830

This very local and generally rare species has a rather restricted European distribution; it occurs from France to northern Italy and Ukraine in the south, although there are also records from Romania, Serbia and Montenegro, and extends north to the UK, Germany and Poland. The distribution is not continuous e.g. it is absent from Denmark and the Netherlands, and the UK represents its northern limit. In northern Europe, but not the UK, it is most frequent in upland and mountain areas from about 400 m to about 2500 m. Here it occurs throughout England and Wales and extends into southern Scotland, it is generally local and scarce but tends to be frequent in the southeast through Kent, Surrey and Sussex. The typical habitat is open deciduous woodland and woodland margins, wooded pasture and parkland with a mix of tree species, a good shrub layer and plenty of herbaceous undergrowth, often on calcareous soils. Adults are active during June and July and only rarely appear a little earlier or later. The species is diurnal but rather elusive, spending most of the time among foliage in lower parts of the canopy and among shrubs, and visiting flowers less frequently than other members of the genus although they fly well and mating pairs may sometimes be seen on umbel flowers etc. Adults may feed on pollen and nectar but they are primarily predatory, taking small insects and early stages. The life history is typical of the genus with predatory larvae developing among leaf litter and soil through the winter and spring and pupating in the soil during April and May. Sampling adults usually involves beating and sweeping plenty of low foliage, they generally occur in small numbers (we have recorded only a single specimen from more than a decade of such sampling in our local woodland) but groups may be seen on flowers or in flight during warm weather.

Rhagonycha translucida 1

Rhagonycha translucida 1

Superficially similar to some pale species of Cantharis and so the genus must be identified correctly; here the middle and hind tarsal claws are deeply divided whereas in Cantharis the claws are unequal and only the anterior claw is toothed. 9.0-11.0 mm. Body entirely pale orange or yellow although the scutellum may be a little darker and the elytra may be gradually, but only slightly, darkened towards the apex, appendages entirely pale. Dorsal surface with very fine pale pubescence. Head widely transverse (from above) with large convex and protruding eyes (much larger in males) and long, converging temples, surface flat between the antennae. Pronotum slightly transverse, broadest behind the middle and narrowed to a rounded apical margin and perpendicular posterior angles, surface weakly convex and narrowly explanate, smooth and shiny, without microsculpture. Elytra very elongate, parallel-sided in males, slightly dilated in females, from rounded shoulders to separately-rounded apical margins, surface uneven and finely-punctured throughout, in places appearing cross-rugose. Legs long and slender; femora and tibiae smooth, tarsi 5-segmented with the third segment expanded but not bilobed and the fourth segment distinctly bilobed.