Pterostichus anthracinus (Illiger, 1798)
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ADEPHAGA Clairville, 1806
PTEROSTICHINI Bonelli, 1810
Pseudomaseus Chaudoir, 1838
This locally common hydrophilic species occurs from lowlands to about 1200m throughout Europe, north to the UK and southern Sweden, and south to Italy, Caucasus and Iran, it extends through Russia to the eastern Palaearctic region and is represented throughout by many subspecies; the nominate subspecies occurs throughout most of the range but is absent from Portugal and several Mediterranean countries including most of the Balkan Peninsula, ssp. biimpressus (Kuster, 1853)occurs in Italy, south east Europe and the Near East, ssp. depressiusculus (Chaudoir, 1844) occurs through the ear East and Asia, ad ssp. hespericus (Bucciarelli & Sopracordevole, 1958) is endemic to Italy. In the UK it is widespread though local across the south of England and South Wales, and more scarce and sporadic further north to southern Scotland and through northern and Western Ireland. Adults are present year-round and active over a long season from early sprig until the autumn, they occur in wetlands generally and especially well-vegetated clay or peaty soils beside standing water or on permanently damp floodplains etc, they are mainly nocturnal but are often active on hot summer days, on the continent they often occur in shaded and moist wooded areas and on wet gravelly substrates in mountain valleys. Mating occurs in the spring and begins soon after the adults have emerged from overwintering in the soil; females are known to build small brood nests in which they deposit their eggs and guard them until the larvae emerge although this instinct applies for only so long because if the eggs do not hatch she will eventually eat them. Larvae develop through the spring and into the summer and pupate in the soil during July and August, this stage lasts for about ten days and new-generation adults appear from August until the autumn. Both adults and larvae are surface predators, feeding on a range if small insects and other animals but they also scavenge carrion and very probably take at least some plant food. Adults are wind-dimorphic and those with fully-developed wings fly well and occasionally come to MV light. They are easy to spot by torchlight and by day will soon become active if the substrate is flooded or disturbed, they tend to occur in numbers and often among numbers of superficially similar carabids, pitfalling is very effective but in such habitats but tends to produce large numbers of carabids and should be done with caution.
10.0-13.0 mm. Entirely shiny black with dark brown appendages, the femora often darker than the rest of the legs. Head with two setiferous punctured beside the large convex eyes, vertex smooth and very finely punctured, clypeus and frons mostly smooth but for a ridge alongside each eye, mandibles robust and protruding, antennae filiform; the basal segment about as long as the third. Pronotum transverse, broadest about the middle and curved to distinct anterior angles and weakly sinuate margin before sharp posterior angles, explanate margin narrow throughout, basal fovea doubled and with a short external keel. Elytra long and flat, with sloping shoulders and a continuously rounded apical margin, in the female with a tiny tooth at the sutural apex, with well-impressed striae including a scutellary striole, epipleura crossed before the apex, interstices flat; the third with three or four (counting one near the basal margin) setiferous punctures joining the second or third striae. Abdominal sternites with fine and dense, sometimes confluent, punctures, in the male the apical sternite is longitudinally impressed. Terminal segment of all tarsi glabrous ventrally. Basal segments of male front tarsi dilated.