Poecilus Bonelli, 1810
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ADEPHAGA Clairville, 1806
PTEROSTICHINI Bonelli, 1810
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This Holarctic genus includes about 140 species of medium sized ground beetles; by far the greatest diversity is in Asian regions and only 13 species of two subgenera are known from North America, the European fauna includes 38 species in 9 subgenera and a further 33 subspecies are known, mostly from widely distributed species. The greatest European diversity is in Mediterranean regions, particularly in the east where many species extend into Asia Minor or further east e.g. P. anatolicus (Chaudoir, 1850), from Bulgaria extends into Asia Minor, P. ispulensis Kabak, 1994 occurs in Armenia and Turkey, while the widespread Eastern Palaearctic P. advena (Quensel in Schönherr, 1806) and P. anodon (Chaudoir, 1868) reach west into European Russia and Ukraine. On the other hand some are widespread in warmer regions e.g. the pan Mediterranean P. gisellae (Csiki, 1930) and P. purpurascens (Dejean, 1828).More restricted species often occur in western regions e.g. P. tyrrhenicus (Csiki, 1930) is known from Spain and northwest Africa while P. laevigatus (Dufour, 1820) is restricted to Spain and France. P. wollastoni (Wollaston, 1854) is widespread in North Africa and the Middle East and occurs on the Atlantic islands but is absent from Europe. Examples of endemics are P. crimeanus (Stranea, 1960) from Ukraine, P. kekesiensis Nyilas, 1993 from Hungary, and P. zaballosi Jeanne & Riuz-Tapiador, 1996 and P. pantanelli (A. Fiori, 1903) from Italy. Regarding subspecies, the European fauna is diverse in this respect; the widespread eastern P. szepligetii (Csiki, 1908) is represented in Hungary by ssp. havelkai (Kult, 1949), the widespread Palaearctic P. sericeus Fischer von Waldheim, 1824 includes four European subspecies, P. lepidus (Leske, 1785) includes five, and P. koyi (Germar, 1824) includes nine. Conversely the widespread P. kugelanni (Panzer, 1797) has no recognized subspecies. Our UK fauna includes only four otherwise very widespread species.
Most species inhabit open and moderately dry situations; especially on heaths and moorland with patchy vegetation on light soils, they often occur on arable land and the commoner species sometimes occur on wasteland or in parks and gardens. They are predominantly diurnal and often run on bare soil or even fly on warm sunny days. Both adults and larvae are mostly predatory, preying on other terrestrial invertebrates. Reproduction usually occurs in spring and larvae develop through the summer and overwinter to produce fresh adults in the spring.
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Formerly included within Pterostichus Bonelli, 1810 but now accepted as a distinct genus. Our UK species may be distinguished from Pterostichus by the bright metallic colouration (although unmetallic and even all black individuals sometimes occur), but more widely many members of the genus are entirely black and closely resemble some of the larger Pterostichus. Poecilus may be distinguished from other Pterostichini by the form of the antennae; here at least some of the three basal segments have a fine longitudinal keel along the dorsal surface. Our UK species are very similar and morphologically distinct from our species of Pterostichus, but foreign species differ widely e.g. the elongate and slender P. coarctatus Lucas, 1842 might be mistaken for any number of Pterostichus, and the much broader and more robust P. cursorius (Dejean, 1828) might even pass for an Abax. Thus the genus is morphologically very diverse but the following description generally applies. Dorsal surface glabrous and at most only finely punctured, brilliant metallic green to blue etc. to dull black, with males commonly more shiny than females. Head smooth between large and protruding eyes, with two setiferous punctures beside each eye and poorly-developed frontal furrows, mandibles short, stout and symmetrical, last segment of all palps elongate and either rounded or truncate apically. Antennae medium in length and often slender, two basal segments glabrous, third segment either glabrous (except for the apical setae) or pubescent towards the apex, in many species entirely black but sometimes with various basal segments pale. Pronotum very variable, from transverse and curved laterally to elongate, broadest about or in front of the middle and simply narrowed or sinuate before sharp or protruding angles, inner basal fovea long and strongly-impressed, outer fovea usually shorter and weaker, sometimes obliterated. Wings present or absent, some species are wing-dimorphic. Elytra usually with well-impressed and punctured striae, including a short scutellary striole, but variable e.g. in P. punctulatus (Schaller, 1783) the elytra are almost smooth and the striae represented by rows of fine punctures which fade towards the apex, interstices usually convex and without, or with only one or two fine dorsal punctures, epipleura crossed before the apex. Legs long and robust. Front tibiae strongly broadened beyond the antennal-cleaning notch, middle and hind tibiae with rows of fine setae, and all tibiae with paired apical spurs that are much shorter than the first tarsomere. Fifth tarsomere setose ventrally in both sexes, front tarsi dilated in males. Some continental species are very similar and sometimes need to be dissected for certain identification, but our UK species are readily separated as follows:
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1.
Antennae completely black. Colour variable; metallic green to coppery, but black specimens occur. [Explanate pronotal margin narrow throughout, basal fovea narrow and parallel, the inner much longer and the outer bordered externally by a strong keel. Wings variable. Elytral striae finely punctured.] 10-14 mm.
-P. lepidus
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Antennae pale at the base, at least ventrally.
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2.
Pronotal margins narrow throughout. Two basal antennomeres brown, sometimes only beneath. Body usually bicoloured; head and pronotum violet to coppery, elytra metallic green, but entirely black specimens occur. [Pronotum evenly curved laterally, basal fovea parallel and rather well developed, the inner much longer than the outer.]Wings variable. Elytral striae moderately strongly punctured. ] 10.5-13.5 mm.
-P. kugelanni
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Lateral pronotal margin gradually broadened from the anterior angles, basal fovea oblique; the outer short and usually widened towards the base. Two basal antennomeres red.
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3.
Head and pronotal base very finely punctured, sometimes almost smooth. Elytral striae finely punctured. Internal margin of hind tibiae with 5-8 dark setae. Fully-winged. Colour very variable. 8.0-11.5 mm.
-P. versicolor
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Head and pronotal base more strongly and densely punctured, the punctures always obvious. Elytral striae more strongly though usually less densely punctured. Internal margin of hind tibiae with 8-11 pale setae. Fully-winged. Colour variable, bicoloured individuals sometimes occur. 9-13 mm.
-P. cupreus
UK species
