Anisoxya fuscula (Illiger, 1798)

This mostly central European species occurs from France to Croatia and Romania, extending south to parts of northern Italy and north to the UK and southern provinces of Sweden, it seems to be uncommon throughout most of this range and is variously considered to be threatened or in decline. In the UK, where it is classified as nationally scarce, it is widespread though very local and generally scarce across south east and central England north to Yorkshire and very sporadic and rare in the west of England and Wales. Adults usually occur among bark on dry and decaying branches of various deciduous trees, especially oak (Quercus L.), beech (Fagus L.), ash (Fraxinus L.), willow (Salix L.), poplar (Populus L.) and field maple (Acer campestre L.), but less often on other species. The typical habitat is woodland and wooded pasture but they may also occur on large isolated trees in hedgerows grassland; in the UK it is generally associated with ancient wood-pasture habitats including willows on floodplains, but the species is probably more eurytopic than this as we swept the species from masses of traveller’s joy (Clematis vitalba L.) growing on hazel (Corylus avellana L.) in a hedge on a calcareous grassland hillside in the Chiltern Hills (South Buckinghamshire) during August 2019. Adults occur from late spring until the middle of summer, they are crepuscular and nocturnal and are fully winged and capable of flight, larvae are known to develop in decaying branches and twigs but otherwise little is known of the biology of the species.

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Adults are small, 2.5-3.5mm, and entirely dark brown with paler appendages (and sometimes margins); a rather nondescript species which may be recognized among our UK fauna by the size and the form of the elytra; broadest near the shoulders and evenly tapering to the apex. Narrow, elongate and somewhat cylindrical, dorsal surface very finely puncture and pubescent throughout. Head mostly reflexed below the prothorax and so at most only narrowly visible from above, vertex and frons flat, eyes large, convex and reniform, terminal maxillary palpomere only weakly securiform and antennae filiform with all segments elongate. Pronotum very convex, broadest across the base and narrowed to a rounded anterior margin, the anterior angles not visible from above, lateral margins finely bordered and basal margin sinuate, the surface evenly convex and lacking basal fovea. Elytra broadest behind the base which is slightly narrower than the base of the pronotum, evenly curved and narrowed laterally to separately-rounded apical margins, surface evenly convex and lacking striae or impressions. Legs long and slender (in life the species can run very rapidly, femora mostly hidden in normal setting, tibiae almost parallel-sided; with obliquely-truncate apical margins and short apical spurs (much shorter than the first tarsomere), tarsi 5-5-4, all with the penultimate segment bilobed. Front tarsal segments elongate but short, the terminal segment longer than the basal segment, basal segment of middle and (especially) hind tarsi much longer than the others, claws smooth and all with a small but distinct tooth at the base.