Nemadus colonoides (Kraatz, 1851)
POLYPHAGA Emery, 1886
STAPHYLINOIDEA Latreille, 1802
CHOLEVINAE Kirby, 1837
ANEMADINI Hatch, 1928
NEMADUS Thomson, C.G., 1867
This Western Palaearctic species occurs in lowland regions across central and southern Europe from France to Ukraine and western Russia and extends north into southern Scandinavia and the UK, it is very local and generally rare over much of this range but especially so in northern regions. In the UK it is widespread and sometimes locally common in southeast England and the west midlands and there are a few records from the West Country and further north but so far it seems to be absent from Wales. Typical habitats are woodland and wooded parkland where it is associated with avian nests and debris in tree hollows etc, it has been recorded from nests of woodpeckers, tits, herons, hoopoes and flycatchers in a range of broadleaf trees including Salix, Quercus, Fagus, Populus, Ulmus, Tilia and Aesculus. Adults occur year-round and may be extracted from old nest material or accumulated detritus in rot-holes and hollows or other situations e.g. we extracted several specimens from a sample of bark taken from a decaying Fagus stump (March, 2014) and found several adults overwintering among dead foliage accumulated in deep bark crevices of a redwood tree, both from a local park. On the continent they have been recorded from leaf-litter around oak trees, in rodent nests and anthills, they are frequently associated with the tree ant, Lasius brunneus (Latreille, 1798 and, the jet ant, L. fuliginosus Latreille, 1798 and have been found around nests of the hornet, Vespa crabro Linnaeus, 1758. Adults are cryptic and can move rapidly and so sieving or extracting suitable material is the best way to find them although they fly and may occur in interception traps.
1.5-2.0mm. Elongate-oval, in outline slightly constricted at the base of the pronotum and elytra and with the head only narrowly visible from above; dark brown but usually paler around the pronotal margins and towards the elytral apex. Head with a distinct occipital ridge, vertex and frons smoothly convex and very finely punctured and pubescent. Antennae pale or variously darker towards the apex but with segment 7 distinctly darker; gradually and only weakly thickened towards the apex, three basal segments elongate, 4-6 quadrate, 8 transverse and much smaller than 7 and 9, terminal segment elongate and pointed. Pronotum transverse, broadest near the base and smoothly narrowed to rounded anterior angles, anterior margin weakly curved and level with the base of the head, posterior margin sinuate, surface finely punctured and pubescent, in places the punctures forming transverse series. Scutellum large, triangular and punctured and pubescent as the pronotum. Elytra slightly narrower than the pronotum across the base, with sloping shoulders and evenly narrowed to a continuously rounded apical margin. Surface densely punctured and pubescent, the punctures forming wavy transverse rows, without longitudinal striae but with a variously-developed impression adjacent to the suture. Legs long and slender; all tibiae with small sharp spurs on the inner apical angle, the middle tibiae also with fine spines on the external angle. Tarsi 5-segmented, pro-tarsi strongly dilated in the male, slender in the female.