Scopaeus sulcicollis (Stephens, 1833)

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POLYPHAGA Emery, 1886

STAPHYLINOIDEA Latreille, 1802

STAPHYLINIDAE Latreille, 1802

PAEDERINAE Fleming, 1821

PAEDERINI Fleming, 1821

Scopaeus Erichson, 1839

This species has a mostly southern and central European distribution; it is locally common from Spain to Greece and parts of Asia Minor in the south and less common and much more sporadic in central and northern Europe, reaching into the UK and some southern provinces of Norway and Sweden. It seems to be absent from most of the Mediterranean islands, it does not occur in North Africa and the eastern limit of the distribution being Black Sea region of Russia. In the UK it is widespread in England, Wales and southern Scotland though very local and scattered, despite this it is our most frequently recorded member of the genus and, being among the smallest of our Paederinae and leading a secluded lifestyle, it is likely to be more common than records might suggest. This is also the most eurytopic of our UK species; it often occurs on sparsely-vegetated sandy or gravelly margins of rivers and reservoirs but also on moist or dry clay, sandy or calcareous soils and has been recorded from garden compost and decaying vegetation on allotments. Adults occur year-round; they overwinter in tussocks or among litter although they may remain active in compost throughout the year, they are active from March until late in the year, peaking in abundance during May and June, although in Northern Europe, where they are sometimes associated with the ant Formica pratensis Retzius, 1783, they are often most abundant in late summer and autumn. Dispersal occurs by flight and so adults may sometimes be swept from grassland etc. or may occur in flight interception traps. Nothing is known of the biology or feeding habits and the larva remains undescribed. Adults often occur under stones or in moss or matted vegetation but sieving compost or litter is probably the best way to find them; decaying vegetation in almost any habitat is worth a look e.g. we found them in numbers by sieving very dry leaf litter at the base of sun-baked, sloping calcareous grassland in the Chiltern Hills far remote from any water.

Scopaeus sulcicollis

Scopaeus sulcicollis

© Lech Borowiec

2.8-3.2 mm. Scopaeus are distinctive among the UK fauna due to the small size and general habitus; the long temples, very narrow neck and quadrangular pronotum are characteristic. The present species may be recognized by the middle tibiae which are distinctly more dilated than the hind tibiae and the temples that are more than twice as long as the eyes. Body uniformly pale brown to black and finely pubescent throughout, appendages pale yellowish-brown. Head with long and slightly diverging temples and a wide base that recurves slightly to a very narrow neck, surface flat and finely punctured, labrum with four well-developed teeth, the median pair much stronger than the lateral pair. Penultimate maxillary palpomere expanded from the base, terminal segment diminutive, hardly noticeable at X40. Antennae inserted anteriorly about the outer margin of the mandibles, scape long and robust, segments 2-6 elongate, 7-10 quadrate to transverse and the terminal segment elongate and pointed. Pronotum elongate and slightly narrower than the head, almost parallel-sided laterally and strongly narrowed to the basal and apical margins, surface finely punctured, more so than the head, and with a longitudinal median impression that is often interrupted along the disc. Elytra quadrate and slightly wider than the pronotum, lateral margin weakly curved and all angles rounded, surface without striae, rugose and moderately strongly punctured throughout. Abdomen long, weakly dilated towards the apex and with narrow raised lateral borders, tergites densely punctured throughout. In males the eighth sternite has two oval impressions towards the apical margin which is smoothly excised. Front femora strongly developed, deeply incised and with longer sensory setae below, middle and hind femora normally developed. Tibiae smoothly widened from the base, the middle pair distinctly wider than the posterior pair, and all with only a very tiny apical spur. Tarsi 5-segmented, basal segments of the middle and hind tarsi short and not, or only very slightly lobed, those of the front tarsi rather strongly dilated in both sexes.