Mycetoporus lepidus Gravenhorst, 1806
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POLYPHAGA Emery, 1886
STAPHYLINOIDEA Latreille, 1802
MYCETOPORINI Thomson, C.G., 1859
Mycetoporus Mannerheim, 1830
This is the commonest and most widely distributed European member of the genus, it locally common from the Pyrenees to Italy, Greece and Ukraine in the south and extends north to the UK, Denmark and far beyond the Arctic Circle in Scandinavia, it is widespread in North Africa and Asia Minor and extends east into Siberia and Mongolia. The first Canadian record was from British Columbia in 1953 and it has subsequently been found in Alberta (1993) and Prince Edward Island (2000), there are no records from the United States and while the current status in Canada is uncertain it is likely to be established. This is the most eurytopic and frequently recorded of our fifteen UK species; it is locally common across southern and central England and Wales and more sporadic and generally scarce further north to the Scottish Highlands. Adults occur in deciduous, coniferous and mixed woodland, open grassland and scrub, heaths and moorland, on freshwater margins with patchy vegetation and occasionally on maritime beaches. They are mostly nocturnal but may occasionally be found running on bare soil or bark during warm weather. Little is known of the biology but adults are known to be predatory and they occur year-round, they overwinter among decaying plant material, in tussocks or under bark etc., and are active from March until September. Adults tend to occur as single specimens and any sample of decaying organic matter is worth investigating e.g. we have found them among decaying terrestrial fungi in a local woodland during October. In the summer they may occur when sweeping or investigating loose bark etc. and they fly well (although it seems seldom so) and so might also be expected from flight-interception traps.
4.0-5.5mm. Elongate and rather parallel-sided, forebody glabrous, abdomen finely pubescent. Head dark brown to black, pronotum and elytra variable, from pale brown to chestnut brown with darker patches, abdomen dark brown with the apical margins of each tergite paler, the terminal tergites often extensively pale. Head rounded in front of large, weakly convex eyes and long temples that converge strongly towards the base, surface smoothly convex with distinct, mostly transverse, microsculpture and a single setiferous puncture beside each eye. Penultimate maxillary palpomere much broader than the previous segment, considerably thickened from a narrow base to a rounded or almost truncate apex, terminal segment elongate and slender. Antennae inserted laterally in front of the eyes and about as long as the head and pronotum combined, 11-segmented and gradually thickened from the base, the basal segments elongate and segments 9 & 10 strongly transverse. Pronotum transverse, broadest across rounded posterior angles and smoothly curved to a narrow apical margin, with four setiferous punctures behind the apical and basal margins, four along each lateral margin and a series of 6-8 in a curved line across the disc. Elytra much longer than the pronotum, more or less parallel-sided behind sloping shoulder to rounded posterior angles and separately recurved apical margins, lateral margins bordered, the sutural margin depressed and with several setiferous punctures. Each with (only) two longitudinal rows of setiferous punctures on the disc, the inner row usually with four or five punctures and the outer row usually with at least seven. Basal abdominal segments strongly bordered, fifth visible tergite much longer than the previous ones, and all tergites finely punctured and pubescent throughout. Legs long and slender, middle and hind femora widely visible in normal setting, all tibiae with stout bristles along the margins. Tarsi 5-segmented, front tarsi short with only the terminal segment elongate, all middle and hind tarsomeres elongate, notably the basal segment which is much longer than the others.