Abdera affinis (Paykull, 1799)

This species occurs sporadically across Central and Northern Europe from the Pyrenees to the Alps in the south and extending beyond the Arctic Circle in Scandinavia. In Central Europe it is very sporadic and generally rare but further north, with the exception of Denmark, it is locally, or even generally (Southern Sweden) common. In the UK it is known from only a few sites in the Scottish Highlands and here it is usually very rare; it is variously classified as critically endangered or possibly extinct. The typical habitat is coniferous or mixed woodland; in the UK usually on Birch (Betula pendula Roth) or pine (Pinus L.), but in Northern Europe on a wide range of broadleaf and conifer species. Adults are active from April until July and peak in abundance towards the end of this season. The overwintering stage is unknown but is likely to be as adults or pupae as larvae occur in the summer and adults are occasionally found during September and October. The species is usually associated with old or decaying sporocarps although adults have also been found among mouldy debris under dead bark and in leaf litter (especially in pine woods) under dead and decaying trees. A wide range of fungal species, including Phellinus conchatus (Pers.:Fr.) Quél, P. igniarius (L.ex Fr) Quél, Fomes fomentarius (L.) Fr., Ganoderma applanatum (Pers.) Pat, Inonotus dryophilus quercina L.: Fr. and I. radiatus (Sow. Ex Fr.) Kickx have been recorded hosting adults and here the beetles tend to occur most commonly during the spring sporolation. In Finland larvae have been reared during the summer months from Rigidiporus corticola (Fr.) Pouzar (on Aspen) and Inonotus obliquus (Pers,: Fr) Pilát (on Birch).

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2.5-3.5 mm. Elongate, narrowly oval and convex above and below, colour variable from entirely pale brown to extensively darkened, often pale with the pronotum and/or head darker, dorsal surface with fine pale pubescence which produces a silky effect in some lights. Head narrowly visible from above in normal setting, in life usually concealed, gently convex and very finely punctured between transverse and convex eyes. Antennae short and broad with segments 5-10 conical, segment 3 slightly longer than 4 and more than 3X longer than 2. Pronotum widest across rounded posterior angles and smoothly narrowed to a curved apical margin, basal margin bisinuate and finely bordered, surface without basal fovea or longitudinal impressions, finely shagreened but not punctured. Elytra gently curved from rounded shoulders to a continuous apical margin, slightly narrower across the base than the base of the pronotum, surface smoothly convex, without striae, finely shagreened but not punctured, Legs long and slender, with femora only narrowly visible in normal setting. Tibiae only slightly broadened from the base, without external teeth or spines, middle and hind tibiae with paired apical spurs which are much shorter than the basal tarsomere. Tarsi 5-5-4 with the penultimate segment narrowly lobed, basal segment of the middle and hind tarsi very long, apical segment long and curved. Claws smooth and without a basal tooth.