Prionocyphon serricornis (Muller, P.W.J., 1821)
Absent from Asia and North Africa and Asia, the European distribution of this species is widespread but discontinuous; it has been recorded from Spain to Greece and north to the UK and southern provinces of Fennoscandia but is absent from many countries and generally rare in northern regions. In the UK it is locally common across Wales and central and southern England north to the Humber, although generally absent from the West Country, and more local and rare to the Scottish border, further north there it has been recorded from central Scotland and there are a few widely scattered records from the north and east of Ireland. Typical habitats include old deciduous woodland and parkland and pasture with a range of older trees in various stages of decay, adults are short-lived and occur from June until July; they generally remain under bark during the day and become active in the evening when they may be swept from foliage or surrounding vegetation, they fly well and are also attracted to light and occur regularly at light and flight-interception traps. Breeding occurs in the summer and larvae develop among detritus and decaying leaves in wet hollows in old deciduous trees, generally near the roots or in cavities formed where low branches have fallen but they have also been found among waterlogged soft heartwood. Larvae are detritivores; they grow through the summer and overwinter to complete their development and pupate in the spring, they have been recorded from a range of tree species but occur more especially on beech (Fagus L.), they sometimes occur among extraction samples and are distinctive, long and fusiform with well-developed legs and antennae, the forebody is mostly pale-creamy and the abdomen mostly dark shiny grey or with the segments diffusely creamy.
Adults are small and rather nondescript beetles which are easily distinguished among our UK fauna by the colour and the form of the antennae. 3.0-4.8mm, broadly elongate-oval in outline, entirely shiny to dull yellowish-brown (some specimens are darkened about the elytral apices) and finely and randomly punctured and pubescent. Head transverse with large convex and strongly protruding eyes and short converging temples, vertex and frons smooth and more-or-less flat, fronto-clypeal suture distinct and labrum wide, narrow and smoothly curved anteriorly, mandibles small but robust and prominent, sharply-pointed and smooth internally. Antennae 11-segmented but appearing 9-segmented as the second segment is small and the third tiny, basal segment broad and rounded, 4-11 rather strongly serrate in the male, in the female only segments 4-6 are serrate and then often more weakly so than in the male. Pronotum short and widely transverse from above, smoothly rounded anteriorly from sharply acute posterior angles and sinuate across the base, surface evenly convex and more finely punctured than the elytra, about the same as the head. Scutellum triangular and relatively large, punctured and pubescent as the pronotum. Elytra with broadly-rounded shoulders and evenly curved to a continuously-rounded apical margin, explanate margin narrow throughout, surface without any trace of striae, the pubescence pale semi-recumbent and overlapping. Legs short and slender, the femora only narrowly visible in normal setting, middle and hind tibiae straight internally and curved externally, the front tibiae narrow and weakly curved, all tibiae with a tiny apical spine. Tarsi 5-segmented, the basal segment longer than the next two combined, the fourth bilobed and the terminal segment elongate.