Philonthus quisquiliarius (Gyllenhal, 1810)
This locally common species occurs sporadically throughout Europe except for the far north and extends east through Asia Minor and Russia to Siberia, Mongolia and China; it is widespread across Mediterranean Africa, including the Atlantic Islands, and the Afrotropical region including Madagascar. A subspecies, P. q. andalusiacus Coiffait, 1966, is endemic to Spain. Beyond this there are scattered records from Southeast Asia and Australia but so far it is not known from the New World. Here it is generally common across Wales and England north to Nottingham and more local and rare north to southern Scotland and across the north of Ireland, it occurs in lowland and upland areas, reaching higher altitudes in mountain river valleys on the continent. Typical habitats are wetland margins, marshes and fens etc, usually among dense vegetation or reed litter on clay or sandy-clay soils where they are often the most common staplylinid, adults are present year-round, they are active from early in the year and common by late spring and early summer. Both adults and larvae predate small insects etc, but they can switch and feed on plant material; both stages can survive on either but it seems both are essential for larval and adult development and adult fertility and fecundity (Garcia et.al. 2007). Adults usually occur in numbers and are easily sampled by sieving or searching through suitable material, they fly well and often appear in flight-interception traps or at light and through the winter in flood refuse and extraction samples of tussocks, moss or litter from suitable habitats.
A medium sized, 5.5-7.5mm, and rather nondescript species; entirely black with brown appendages or, rarely, with the elytra substantially bright red (var. inquinatus Stephens, 1932). Head quadrate or slightly transverse, with weakly convex eyes and rounded posterior angles, surface with very fine transverse microsculpture, a pair of punctures near the anterior margin of each eye and scattered large punctures along the margins of the eyes and across the base. Antennae moderately long; almost reaching the base of the pronotum, with all segments elongate. Palps and basal antennomere red, antennae otherwise dark or with the base of some segments pale, terminal maxillary palpomere contracted towards the base and a little longer than the penultimate segment.
Philonthus quiquilliarius 1
Philonthus quiquilliarius 2
Pronotum quadrate and slightly narrowed from rounded posterior angles, with a longitudinal series of five strong punctures either side of the middle and scattered punctures towards the lateral and basal margins, surface with fine linear microsculpture (which may be virtually absent on the disc) that appears coppery when viewed under good lighting at the right angle-this reflection is a good clue to the identity. Elytra quadrate and gradually broadened from rounded shoulders to sharp posterior angles, basal margin sinuate laterally, surface without microsculpture, closely punctured and with pale overlapping pubescence. Abdomen shiny and without microsculpture, the raised lines across the base of the first three visible tergites sinuate and weak, punctation finer that that on the elytra, becoming less dense apically, pubescence similar to that on the elytra. Femora pale brown, tibiae often a little darker, basal segment of hind tarsus shorter than the terminal segment and thicker than the others. Basal segments of front tarsi strongly dilated in the male, only moderately so in the female. Aedeagus characteristic, asymmetrically constricted before a sharply pointed median lobe.