Atomaria atricapilla Stephens, 1830

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POLYPHAGA Emery, 1886

CUCUJOIDEA Latreille, 1802

CRYPTOPHAGIDAE Kirby, 1826

ATOMARIINAE LeConte, 1861

ATOMARIINI LeConte, 1861

Atomaria Stephens, 1829

Anchicera Thomson, C.G., 1863

This mostly Western Palaearctic species is generally common throughout Europe and Asia Minor and extends east into Siberia, also known from many of the Mediterranean islands, North Africa and Iceland; in Europe it is reaches north to the UK, Denmark and the Baltic countries; in Norway and Sweden reaching the Arctic Circle but in Finland it is very rare and known only from the extreme south. In the UK it is generally common throughout England and Wales, including all the islands, much less so further north to the Western Isles, Orkney and Shetland and in Ireland it is widespread but mostly coastal in the south and east. The species is usually associated with decaying vegetation in a wide range of habitats including damp grassland and arable land, but it is sometimes common among compost or grass cuttings in gardens or in hay or straw in stables and farms etc., and in Europe it is often common among vegetation on dry slopes and woodland margins in mountain valleys etc. Adults occur year-round; they overwinter among tussocks or damp litter and are active from March until November or December, peaking in abundance from May until July. They fly well and often visit umbel flowers etc. in numbers during warm weather but otherwise remain hidden among litter etc., although in the autumn they sometimes occur in large numbers among pungent decaying terrestrial fungi in damp situations and here they tend to be active through the night. The biology is not known but larvae probably develop among decaying vegetable matter and are mycophagous or saprophagous. Adults can be sampled by sieving or taking likely samples for extraction, but they sometimes occur when sweeping long vegetation or in flight-interception traps.

Atomaria atricapilla

Atomaria atricapilla

© Lech Borowiec http://www.cassidae.uni.wroc.pl/Colpolon/index.htm

1.3-1.6 mm. Elongate and rather narrow with the pronotum and elytra separately curved, head black or dark brown, pronotum dark brown or reddish brown, sometimes narrowly darker across the base, Elytra brown with the area around the scutellum or the base of the suture darkened, appendages pale brown. Head usually only narrowly visible from above, evenly and weakly convex between large and slightly protruding eyes that continue onto the front margin, clypeus converging and projecting beyond the eyes and between the antennal insertions. Antennae inserted close together on the anterior margin, separated by about the length of the basal segment, 11-segmented with the basal segment broad, 2-8 slender and 9 & 10 quadrate and broader,  forming a distinct (rather than gradual) club. Pronotum transverse, broadest about the middle and narrowed to rounded (from above) anterior angles and obtuse posterior angles, lateral margin finely bordered, this being visible from above from the middle to the base, surface evenly convex but for a variable transverse depression in front of the base, punctures large and dense, almost touching in places, pubescence radiating out from the centre of the disc and more or less arcuate in the apical half. Scutellum transverse. Elytra evenly curved from sloping shoulders to a continuous apical margin that covers the abdomen, surface without striae, across the base a little less strongly and densely punctured than the pronotum, reflexed laterally so that the margins are not visible from above. Legs short and slender with narrow femora and tibiae hardly broadened from the base. All tarsi with five simple segments.