Scaphisoma agaricinum (Linnaeus, 1758)
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POLYPHAGA Emery, 1886
STAPHYLINOIDEA Latreille, 1802
SCAPHISOMATINI Casey, 1893
Scaphisoma Leach, 1815
Of the 8 central European species of Scaphisoma the present one is generally by far the most common, it is a widespread European and Asian beetle extending from North Africa to beyond the Arctic Circle in Scandinavia and from Portugal to Asia Minor, Turkestan and southern and central Siberia; in the UK it is locally common throughout England and Wales, becoming more sporadic in the north and in Scotland there are a few records from the north-eastern Highlands. Adults occur year round, peaking in late summer and early autumn, and are associated with fungus- infested decaying wood in a wide range of habitats; broadleaf, mixed and coniferous woodland, parkland and gardens etc. in fact anywhere the host material occurs, and they seem to be quite tolerant of disturbance and human presence e.g. we have seen them in numbers on stumps beside footpaths and sports areas in our local parks. They are easily observed on or around decaying fungoid wood at night as they are nocturnal, but they will also become active during the day in very warm spells in spring and summer, generally running around on logs or stumps that have been cut close to the ground, they run very rapidly and vanish into crevices as soon as they are disturbed and so need to be spotted and pootered quickly; they are distinctively dark in colour but this is hardly discernible until they are tubed. Beyond such searching they will turn up year-round and regularly in extraction samples of appropriate material; fungi and dead bark along with the associated sub-cortical debris. They will generally be found around decaying logs, under mouldy bark, among rotten wood in stumps, deep decayed leaf-litter or, occasionally, at sap. They seem to be rather generalist at fungi as adults have been recorded from the following species: Trichaptum pargamenum (Fr.), Trametes versicolor (L.: Fr), Rigidoporus corticola (Fr.), Piptoporus betulinus (Bull:Fr.), Phellinus igniarius (L.:Fr.), Inonotus obliquus (Pers:Fr.), Inocutis rheades (Pers.), Ganoderma lipsiense (Batsch), Fomitopsis pinicola (J. Sowerby:Fr.), Fomes fomentarius (L. : Fr.), Daedalea quercina Fr., Cerrena unicolor (Bull.:Fr.) and Bjerkandera adusta (Willd.:Fr.).
1.7-2.0mm, although tiny these very distinctive insects will soon become familiar in the field as they could only be confused with other members of the genus; no other UK beetles are remotely similar. Distinguished by the form of the elytra; black with a distinct sutural stria that is curved under the scutellum but does not continue along the basal margin. Body continuous in outline; entirely shiny black or with the elytra diffusely pale towards the apex, appendages pale. Head usually concealed from above, smoothly convex and produced anteriorly in front of relatively large convex eyes, antennae inserted at the lateral clypeal margin, antennae long and slender with the last 5 segments expanded internally. Pronotum broadest at the base and evenly curved around the anterior margin (from above), smoothly convex and finely punctured throughout, lateral margin finely bordered, basal margin strongly sinuate and covering the scutellum. Elytra evenly curved and convex, broadest about the middle and narrowed to truncate posterior margins that leave at least the pygidium exposed, each with a strongly impressed and impunctate sutural stria that terminates just before the apex, otherwise without striae, punctation a little stronger and sparser than on the pronotum. Pronotum and elytra with sparse very short pubescence.