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Clambus armadillo (De Geer, 1774)






POLYPHAGA Emery, 1886

SCIRTOIDEA Fleming, 1821

CLAMBIDAE Fischer von Waldheim, 1821

CLAMBINAE Fischer von Waldheim, 1821

Clambus Fischer von Waldheim, 1821

This is a mostly central and northern European species; it occurs from lowland to lower mountain altitudes from France, Italy and northern parts of the Balkans north to the UK and above the Arctic Circle in Scandinavia, to the east it extends into Ukraine and western parts of Russia but is absent from Asia Minor and North Africa, following introductions it has become established in several northern regions of the United States and has more recently become established around Nova Scotia. In the UK it is locally common across southeast and central England and Wales, very local and generally scarce further north into central Scotland and in southwest Ireland.  Adults occur year-round and are common through the spring and summer, they usually associated with decaying vegetation in wetland or permanently damp situations, often among litter and decaying plant debris or among moss etc, while in Northern Europe they are more eurytopic, occurring on open grassland, scrub and bogs, they are frequent among decaying litter in both broadleaf and conifer forests and may be quick to colonize freshly planted areas. Little is known of the biology but both larvae and adults are thought to be mycophagous. Sampling these tiny beetles can be difficult; sieving likely material over a sheet is probably the best method in the field as they can be nimble and are easily seen as they run, but they can also curl up and remain still for long periods and so are very difficult to spot, they very occasionally appear when sweeping marginal vegetation or long grass in hot weather but taking samples of deep decaying vegetation for extraction will often produce the species at any time of year.

Clambus armadillo

Clambus armadillo

© U.Schmidt

1.0-1.3 mm. Tiny beetles; broadly-oval, convex above and discontinuous in outline. Among the UK fauna the only similar genus is Calyptomerus Redtenbacher, 1849, here the head is much broader relative to the pronotum, the pronotum lacks posterior angles and the eyes are situated on lateral extremity of the head. Body black, usually with the lateral and basal pronotal margins paler reddish, legs and antennae pale brown, head and pronotum distinctly shagreened. Head widely transverse and distinctly narrower than the pronotum, eyes flat and situated inside the lateral angle behind a short oblique impression, surface convex and extremely finely punctured and pubescent. Antennae 10-segmented with a broad basal segment and an elongate two-segmented club. Pronotum broadest near rounded posterior angles and narrowed to a rounded anterior margin, surface evenly convex with extremely fine punctures and oblique pale pubescence. Elytra slightly narrower across the base than the base of the pronotum, with sloping shoulders and curved laterally to a continuous apical margin, surface dull but only obscurely microsculptured; towards the apices sometimes wrinkled but otherwise smooth, punctures extremely fine and mostly indistinct, pubescence recumbent and long; the hairs longer than the distance between the hairs. Legs very slender, the hind coxae broadly expanded to cover the femora in repose, tarsi 4-segmented and simple, claws smooth and separated at the base. Similar to our other members of the genus but distinguished by the obscure punctation and long pubescence on the elytra.

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