Gabrius splendidulus (Gravenhorst, 1802)
A generally common and often abundant species throughout most of Europe, extending north far beyond the Arctic Circle in Scandinavia, and east to Siberia; in the UK it is locally common across Wales and England north to the midlands although generally absent from the West Country. On the continent it occurs from lowland to low mountain altitudes, extending to the alpine zone along river valleys. In the Nearctic region it is known from a few specimens from both the east and west coasts of America and has been recorded from British Columbia since before 1884 The typical habitat is woodland and wooded parkland but it may occur wherever there is decaying timber, including domestic gardens, and it will often occur among decaying fungus. Adults occur under bark and among dead and decaying wood on logs, standing trunks and stumps of both conifers and broadleaf trees, they tolerate a wide range of conditions from dry and powdery loose bark to tight-fitting and damp bark around areas of decay on otherwise healthy trees; they often occur alongside other beetles e.g. we have found them among populations of Siagonum quadricorne Kirby, W., 1815, Silvaus bidentatus (Fabricius, 1792) and Endomychus coccineus (Linnaeus, 1758), among many others, but they may also be the only beetles present. They occur year-round, in spring and summer among wood but in the autumn often in decaying fungi both on wood and on the ground, here they may persist in numbers through the autumn and into the winter, otherwise they often occur in extraction samples of bark and associated moss and debris or leaf-litter from wooded situations. Adults are readily found by removing dead bark or by general searching but they are nocturnally active on the surface and easily seen by torchlight.
4.0-5.5mm. Head and pronotum black with fine wavy microsculpture (X40), elytra dark brown or paler towards the base and abdomen brown with the apex of each segment pale. Head quadrate or slightly elongate, with long and parallel temples, rounded but distinct posterior angles and narrowed in front of the eyes. Vertex transversely impressed, sometimes with a small central fovea, and with several punctures close to each eye. Antennae inserted within the base of the mandibles, pale or slightly darkened towards the apex; segments 6-10 transverse. Pronotum elongate and parallel-sided with the lateral margins finely bordered and the anterior and posterior angles rounded, disc with a longitudinal series of 5 large punctures (sometimes an extra one is present on one side) and another series of 3 or 4 between these and the margin. Scutellum large, pubescent and microsculptured as the pronotum. Elytra longer than the pronotum, with prominent shoulders and widened towards the apex, smooth and shiny, with strong diffuse punctation and oblique, recumbent pubescence, posterior margin strongly sinuate. Abdomen shiny, with fine and sparse punctation and scattered erect setae among very fine recumbent pubescence, in the male the eighth tergite is sinuate apically. Legs pale or with the tibiae and/or tarsi a little darker; femora robust and broad, especially the middle pair, and tibiae long and slender with several groups of stout spines along the outer margin and a pair or terminal spurs. Tarsi 5-segmented , all segments narrow in both sexes, the second pro-tarsomere elongate, claws smooth and without a basal tooth.
This small rove beetle is readily recognized by the combination of elongate pro-tarsal segments, 5 punctures in the pronotal series and pale antennae with segments 6-10 transverse.