Platystethus capito Heer, 1839
This species is very widespread though sporadic and generally very local and scarce throughout the western Palaearctic region; the distribution extends from Europe and North Africa to Central Russia and there are records from the eastern Palaearctic region though it is absent from China and Japan. In Europe it is most frequent in southern and central regions where it occurs from lowlands to lower mountain altitudes, to the north it extends to the UK and the Baltic countries but not into Fennoscandia although specimens have been reported from Norway among containerised plants imported from Germany. The majority of UK records are from East Sussex, Kent and East Anglia, beyond this there are widely scattered records from the midlands and the Severn estuary, and while it is generally very local it tends to be common where it occurs and it may well be under-recorded. Here it is usually associated with sparsely vegetated areas of chalk and limestone, often on very dry hillsides and meadows but also on damp chalk in pits or floodplain grassland. Older UK records from marshland have proved to be from other, misidentified, species. On the continent it also occurs on basic substrates but is frequently recorded from sandy areas and records suggest it may also be associated with peaty soils; it is not generally a marshland or riparian species although it has been recorded from wet clay pits and peat bogs in Poland. Adults have been recorded from January until October and it is likely they overwinter; they peak in abundance during June and July and remain common into September. Little is known of the biology but larvae have been recorded in the summer. Adults may be found under stones and debris or among soil around tussocks, they appear in pitfall and flight-interception traps and, in late spring and early summer they occasionally swarm, either on bare soil or in flight above grass.
Platystethus capito 1
Platystethus capito 2
2.5-3.0 mm. Body entirely shiny black, antennae dark brown, legs paler brown with yellowish tarsi. Forebody and elytra without microsculpture, abdomen with faint, mostly transverse, cellular microsculpture. Head broadest across small convex and protruding eyes, with long converging temples and short, parallel cheeks, clypeus strongly narrowed beyond the antennal insertions and produced anteriorly, surface with scattered strong punctures which are confluent in places, and often with sparse pale pubescence. Penultimate maxillary palpomere elongate and gradually broadened from the base, terminal segment long and slender. Antennae inserted laterally in front of the eyes and outside the base of the mandibles, 11-segmented and gradually thickened from the forth segment. Pronotum widely transverse, broadest in front of the middle and narrowed in an almost straight line to a rounded posterior margin, lateral and basal margins very finely bordered, apical margin not bordered, surface very strongly and, in places, confluently punctured and with a median longitudinal impression. Pronotal pubescence sparse but usually distinct. Elytra transverse and dilated from rounded shoulders to separately curved apical margins, sutural and apical margins distinctly bordered, surface without striae, punctured as the pronotum and with distinct pale pubescence which, at least in places, overlaps. Abdomen short and rounded laterally, tergites strongly bordered and with sparse scattered punctured and pale pubescence. Legs long and slender; femora unmodified, front and middle tibiae with a single row of spines along the external margin. Tarsi 3-segmented, the basal segments short and unmodified and the terminal segment long and curved. Claws smooth and lacking a distinct basal tooth. The sexes are similar in that males lack spines on the clypeus, although the head is usually broader than in females, but in males the apical margin of the eighth sternite is produced into two long lateral teeth.