Patrobus assimilis Chaudoir, 1844
This is a locally common central and northern European species extending south to Switzerland and Austria and east to the Russian border, here it inhabits mainly upland and mountain regions while in lowland areas it is a very local species of postglacial deposits and raised bogs, to the north it is generally more common and extends to the UK and far beyond the Arctic Circle where it is sometimes the most abundant carabid of subalpine birch forests. In the UK it is locally common throughout Wales and England north of Leicester, extending north to the Western Isles, Orkney and Shetland, it is widespread though local and mostly northern in Ireland and there are records from the Faroe Islands. Typical habitats are among vegetation on dry or peaty soils in upland areas, usually grassland, heather moorland and open woodland but higher up, above 300m, it is more eurytopic, occurring in wet peatland, among sedges etc. along stream margins and among moraine in sparsely-vegetated rocky situations. Adults are active over a long season, from March until late in the year depending on the season, although they may also be active after a fall of snow, they are mostly diurnal at higher latitudes and altitudes and often occur alongside other carabids, they reproduce in the autumn and larvae develop over two years in higher latitudes. In the UK adults are consistently short-winged and flightless.
6.5-9.0mm. Entirely dark brown with paler appendages and glabrous but for the usual sensory setae, superficially similar to some Pterostichus but distinguished by the form of the temples and the antennae pubescent from the third segment. Head with temples strongly contracted to a basally diverging neck, eyes large and convex, vertex with a transverse punctured furrow just behind the eyes and frontal furrows parallel to the lateral margin, mandibles sharp and protruding forward, the cuticle between transversely wrinkled. Antennae moderately broad with the segments distinctly curved laterally, the third segment about as long as the basal segment. Pronotum transverse, widest in the apical half and strongly sinuate to perpendicular or slightly protruding posterior angles, basal fovea wide, shallow and moderately strongly and densely punctured, transverse subapical groove shallow and finely or moderately strongly punctured, medially joining a longitudinal impression which continues to the base. Elytra with rounded but narrow shoulders and a continuously curved lateral margin, basal border absent inside the shoulders, striae complete and punctured to the apex, more strongly so about the base, interstices weakly convex, the third with three or four setiferous punctures beside the fourth stria. Male with two basal pro-tarsomeres dilated.