Colenis immunda (Sturm, 1807)

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POLYPHAGA Emery, 1886

STAPHYLINOIDEA Latreille, 1802

LEIODIDAE Fleming, 1821

LEIODINAE Fleming, 1821

PSEUDOLIODINI Portevin, 1926

Colenis Erichson, 1842

Widespread across Europe from Spain to Italy and Hungary with occasional records from Asia Minor and Western Russia, to the north reaching into the UK, Denmark and southern parts of Fennoscandia; it is locally common in the Pyrenees and across Southern France but otherwise very local and scarce in the south where an increasingly drier climate may be causing a slow decline, it becomes more frequent further north and is locally common in central and northern regions. In the UK it is widespread but very local and generally scarce across South-eastern and Central England and Wales and there are a few records further north and in Ireland. Typical habitats are damp deciduous woodland and wooded grassland but they also occur on disturbed ground in urban areas. Adults occur year-round; they are active from May until August or September and peak in abundance during June. During spring and early summer they often occur in mosses or among well-decayed and mycelium-infested leaf-litter on damp ground but they are more generally associated with fungi. They sometimes occur in numbers in truffles (they are known to attack Summer truffles, Tuber aestivum (Vittad, 1831) but specific host associations are unknown) and they seem to be strongly attracted to truffle volatiles but beyond this they occur in a wide range of terrestrial fungi and larvae have been reared from several species. Adults are generally nocturnal; they may be seen on bark or host fungi and may be swept from vegetation, usually before sunrise, but they otherwise remain hidden and so likely material will need to be sieved or taken for extraction. Despite being scarce the species usually occurs in numbers where found but because of its small size and cryptic lifestyle it is likely to be under-recorded.

Colenis immunda 1

Colenis immunda 1

Colenis immunda 2

Colenis immunda 2

Colenis immunda 3

Colenis immunda 3

1.3-2.0 mm. Elongate and broadly-oval, glabrous, entirely dark to pale brown, usually with the antennae a little paler than the body and the legs a little darker. Head broadly transverse, with very fine transverse reticulation and a few scattered punctures between weakly convex eyes, frontoclypeal suture obvious between the antennal insertions. Antennae 11-segmented with a 5-segmented club; segment 7 transverse, 8 diminutive, 9 and 10 transverse and 11 oval. Pronotum transverse, broadest across slightly obtuse posterior angles and narrowed to projecting anterior angles, apical and basal margins smoothly curved, lateral margins finely bordered, surface evenly convex and smooth or with extremely fine transverse reticulation. Elytra smoothly curved and narrowed from rounded shoulders to a continuous apical margin, sutural stria well-impressed from the apex to about the middle, striae otherwise represented by rows of fine punctures which tend to be irregular or only present towards the base, surface with strong transverse reticulation, especially in the basal half. Femora broad, flat and excavate to receive the tibiae, in males the hind femora have two small teeth, the lower tooth sharp. Tibiae straight, with external rows of fine spines and paired apical spurs. Tarsi 5-4-4 in both sexes, all segments simple, in males the front tarsi are slightly dilated. Claws tiny, smooth and without a basal tooth.