Scydmaenus tarsatus Müller, P.W.J. & Kunze, 1822
This species occurs throughout Europe from northeast Spain to northern Italy, the Balkan Peninsula and into Asia Minor and western Russia, to the north it extends to the UK southern Fennoscandia, reaching the Arctic Circle along the coast of Sweden, it is also widespread in North Africa and is present on the Canary Islands. Here it is widespread and locally common across England and Wales, it is very local and scarce in the West Country but is present on Scilly, Anglesey and Man, further north there are a few scattered records north to the Scottish Highlands. Adults are present year-round, peaking during in late spring and early summer and again in the autumn, they occur among fairly dry decomposing plant remains in a variety of habitats but may be abundant in garden compost and undisturbed hay and straw, they have also been recorded from decaying wood and found among various species of ant, they disperse by flight and so might be expected from any suitable host material. Both adults and larvae are predaceous but unlike many species of the subfamily they feed on soft-bodied prey, they ignore oribatid and uropodine mites but readily take soft-bodied acaridid mites as well as a range of small insects and springtails, they will also scavenge dead insects etc and in large populations may become cannibalistic. Adults overwinter among leaf-litter etc or in the soil and will occasionally appear among extraction samples, during the warmer months they are easily sampled by sieving suitable material over a sheet, they are generally slow-moving and very easy to spot in the field.
2.0-2.1mm. Body shiny dark reddish-brown, the forebody sometimes almost black, with very fine and sparse punctures and long semi-recumbent pale pubescence, appendages paler brown. Head transverse with weakly convex eyes and long temples that converge towards a truncate basal margin, maxillary palps long and slender, the terminal segment long and gradually broadened to a rounded apex. Antennae 11-segmented, inserted anteriorly and separated by about the length of the basal segment. Basal antennomere long and broad, with a distinct sub-apical notch (which will separate the genus from our other genera), segments 2-5 elongate (the two basal segments sub-equal in length), 6-8 quadrate or nearly so, and 9-11 forming a gradual elongate club. Pronotum elongate, broadest about the middle and strongly narrowed to a rounded apical margin, the anterior angles hardly discernible, posterior angles obtuse and basal margin slightly curved, surface evenly convex but for four strong fovea in anterior to the basal margin. Elytra elongate, with sloping shoulders and evenly-rounded lateral margins, apical margin continuously curved and covering the abdomen, without striae but with a variously-developed depression inside the shoulders. Legs long and slender; femora thickened distally, tibiae gradually and only weakly expanded towards the apices. Tarsi 5-segmented, without obviously lobed segments, the pro-tarsi slightly wider in the male.