Callistus lunatus (Fabricius, 1775)
This exquisite little carabid was last recorded with certainty from the U.K. in 1964, the most recent record previous to this being from 1953, and it is now probably extinct here. On the continent it is very widespread although the distribution is patchy, in part no doubt reflecting its ecological requirements, and it seems to be nowhere common. It occurs locally from Portugal to Central Russia, Ukraine and Turkmenistan; to the south it extends to the Balkans, Asia Minor and parts of the Middle East and in the north to Germany and Poland, it is known from only a few sites in many of the northern countries and is generally considered to be endangered. Two regional subspecies are recognised; C. lunatus gratiosus Mannerheim, 1884 from Iraq, and C. lunatus syriacus Pic, 1893 from Syria. In the U.K. it was once widespread but very local in the southeast; Kent, Surrey and Berkshire, but there was a drastic decline over the twentieth century and it is now optimistically classed as critically endangered. The species is diurnal and thermophilic and more or less confined to lowland areas although it reaches up to 1300 m in Central Europe. Typical biotopes are sandy or limestone areas, especially on warm and dry calcareous grassland with a patchy and varied mix of vegetation which often includes thyme (Thymus L.) although in southern Europe, where it is sporadically common, it has been recorded from meadows, vineyards and even domestic gardens with no clear link to limestone or sandy soils. Adults are fully winged but they have not been observed to fly, they are active in warm sun, running in the open among short patchy vegetation and there may be a complex ecological relationship with in this habitat as they have often been observed among thyme growing through or near to nests of the Yellow meadow ant (Lasius flavus (Fabricius, 1782)). Reproduction occurs in the spring and new-generation adults appear in September, these overwinter in loose soil and become active from May. Populations peak in spring and autumn and adults may die off after June or July and so become scarce, in all but the warmest weather they may be found under stones or among tussocks around the base of trees and stumps etc. or under bark.
Callistus lunatus 1
This species is unlikely to be confused with any other UK carabid; the uniquely patterned and coloured dorsal aspect is distinctive. 6-7mm. Head densely punctured, black and usually with a distinct blue or greenish metallic lustre, inner margin of eyes bearing a single setiferous puncture and antennae pubescent from the third segment pubescent. Pronotum various shades of red, not metallic, cordate, with hind angles sharp and weakly protruding, disc densely and often transversely punctured and so appearing cross rugose. Elytra yellow, each with three well-defined large black or slightly metallic marks, the subapical ones usually meeting the suture, striae weakly impressed and punctured, interstices more or less flat. Epipleura not crossed. Pronotum and elytra finely and densely pubescent. Appendages dark except the tibiae, palps and antennal base variously lighter. Tarsi finely pubescent. Male with basal pro tarsal segments dilated.