Tasgius winkleri (Bernhauer, 1906)
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POLYPHAGA Emery, 1886
STAPHYLINOIDEA Latreille, 1802
STAPHYLININI Latreille, 1802
Tasgius Stephens, 1829
Widespread in Europe but generally very local and infrequent, there are records from Portugal to northern Italy and Greece in the south and to the north it extends into the UK and Denmark, it is very rare in Poland and Latvia and otherwise generally absent from the Baltic region although it is locally common along the southern coast of Sweden and it seems to be common on Gotland. The species has been present in North America since the 1930s and is now established in eastern Canada, Michigan and Pennsylvania; it is thought to originate from adventive European specimens and the range seems to be expanding. In the UK it is locally common in south east and central England but otherwise scarce in southern and eastern England, Wales and the Isle of Mann, and there records from the far north of Scotland. Adults occur year round, they are active over a long season from late winter until October or November and peak in abundance during spring and autumn, in warmer continental areas they tend to be active year-round. Typical habitats are open and dry grassland, often on calcareous soils, or among patchy vegetation on poor soils exposed to the sun although they sometimes occur in odd places e.g. under boulders on beaches etc. In Europe they frequent similar habitats and also occur in gardens and woodland margins but in North America they are more widely eurytopic, occurring also on wetland margins and shorelines and more generally occupying disturbed areas with frequent human activity. Both adults and larvae are terrestrial predators; little is known of the biology but it is likely that reproduction occurs in the spring and new generation adults appear late in the year, whether the larvae overwinter is not known. Adults are mainly crepuscular and nocturnal but they often become active on the warmest of days; at night they are active on the surface, they move very quickly and when disturbed can vanish rapidly into the soil or among litter, they are attracted to pungent decaying plant matter and fungi with abundant fly larvae etc, and we found several attracted to a partly exposed subterranean fungus on sun-baked calcareous grassland in the Chiltern hills. By day they generally remain under debris, matted vegetation or in old straw or compost etc where they are easily found by sieving etc. Specimens will need to be examined very carefully as several similar species occur commonly across the range.
14-17 mm. A large and robust species with the head, pronotum and elytra of almost similar width (the pronotum usually a little narrower), body entirely black, the forebody usually with a faint metallic blue lustre, antennae black with the last two segments paler, palps variable from red to black, legs black or with the tarsi and, sometimes, front tibiae reddish. Head transverse with rounded temples behind obliquely-transverse eyes, genae strongly converging to the antennal insertions, surface densely punctured although less so on the disc, with scattered tiny punctures and dark, short and sparse pubescence. Temples at most only slightly longer than the eyes. Mandibles long, curved and slender, internally without teeth and smoothly curved or sinuate about the middle. Terminal maxillary palpomere elongate and rounded apically. Antennae long and slender with all segments elongate. Pronotum elongate, parallel-sided or broader in front of the middle and slightly tapering to rounded posterior angles, anterior angles rounded to a straight or slightly sinuate apical margin, basal margin evenly curved, surface densely punctured; more so towards the lateral margins where they become confluent, except for a variable and narrow unpunctured median strip from the base, pubescence short and dark. Scutellum large, triangular and dull due to dense microsculpture. Elytra slightly elongate, weakly dilated from sloping shoulders to rounded posterior angles and recurved apical margins, surface densely punctured and roughly-sculptured throughout. Abdominal tergites finely punctured and with cellular microsculpture throughout, in females the last visible tergite is evenly rounded apically. Males may be distinguished by the more strongly dilated front tarsi. Sometimes very similar to T. melanarius or T. globulifer but with a weaker blue lustre and more densely punctured pronotum, especially laterally where it is confluent. In doubtful cases the rounded last tergite in females is distinctive (in melanarius it is triangular, and in globulifer it is produced medially and pointed), and in males the aedeagus distinctive; the median lobe is asymmetric and curves before the tip.