Proteinus ovalis Stephens, 1834
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POLYPHAGA Emery, 1886
STAPHYLINOIDEA Latreille, 1802
Proteinus Latreille, 1797
This is a mostly western, central and southern European species; in the south it occurs from Spain to Greece and it has recently (2001) been recorded from Turkey, it is present on many of the Mediterranean islands but is not recorded from North Africa, to the north it extends into the UK, Germany, Denmark and Poland and there are records from southern Sweden, and to the east into Ukraine and parts of European Russia. The species occurs from lowlands to lower mountain altitudes and, with the exception of the UK, is generally sporadic and scarce throughout its European range. With the exception of the West Country it is generally common across most of England and Wales north to the Humber and much more local and scarce further north to the Scottish Highlands and in Northern Ireland. Adults are present year-round; they overwinter among host material and are active from April until October, peaking in abundance during spring and autumn, although they generally remain active through all but the coldest winter spells. Typical habitats are all types of woodland, grassland, scrub and wetland margins but they are very eurytopic; in Europe they are recorded from Lowland meadows and chalk grassland to subalpine grassland and hillside woodland, they occur in gardens, vineyards, lake and river margins, coastal dunes and marshes and they have been recorded from caves. Little is known of the biology but both adults and larvae are thought to be saprophagous and fungivores, feeding on decaying organic material and associated fungal spores and hyphae. Large numbers of adults may occur in decaying sporocarps, especially among aggregates of large terrestrial bodies that have decayed and become ammoniacal, or among compost or decaying material in wetland situations, but they seem to be infrequent in dung and carrion. They may be sieved in numbers or found in extraction samples at any time and they occur on pitfall and flight-interception traps, but the easiest way of finding them is to work decayed fungi over a sheet, especially in late winter or early spring when large populations often occur.
1.8-2.2 mm. Elongate-oval, on average narrower than our other members of the genus, body entirely dark brown to black, antennae dark or with the basal segment a little lighter, legs entirely pale yellowish-brown. Forebody and elytra very finely microsculptured and with sparse pale pubescence. Head transverse, broadest across large and prominent eyes, temples strongly constricted to a broad neck, clypeus broadly produced anteriorly and curved apically, surface depressed obliquely inside the eyes, otherwise smoothly convex, without ocelli. Antennae inserted laterally in front of the eyes, 11-segmented; two basal segments broad and elongate, 3-8 gradually shorter and broader with 8 distinctly transverse, and 9-11 forming a gradual and rather indistinct club. Pronotum transverse, about 2X wider than long, broadest about the middle and clearly narrowed to obtuse posterior angles, anterior angles rounded and slightly projecting, apical margin curved. Basal margin curved backwards and slightly sinuate before the lateral margin, very finely bordered (this must be looked for very carefully at a range of magnifications from X20 to X50), surface without depressions or structure and very finely punctured. Elytra elongate (about 2.5X longer than the pronotum) and gently dilated from sloping shoulders to separately-curved apical margins, surface deeply and rather densely punctured, these often forming partial transverse series. Abdomen broad and smoothly rounded laterally, tergites strongly bordered and extremely finely punctured throughout, without impressions or structure. Legs long and very slender. Femora unmodified. Front tibiae weakly broadened from the base and obliquely-truncate apically, middle and hind tibiae slender throughout. Sexual dimorphism is not obvious but in males the basal protarsomeres is dilated and they have numerous small tubercles on the apical third of the inner margin of the hind tibiae. Tarsi 5-segmented, the basal segments short and unmodified and the terminal segment long and curved.