Oxyporus rufus (Linnaeus, 1758)
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ADEPHAGA Clairville, 1806
STAPHYLINOIDEA Latreille, 1802
OXYPORINAE Fleming, 1821
OXYPORUS Fabricius, 1775
This is among the most widespread of the Palaearctic Oxyporinae. It is locally common from lowland to mid-mountain altitudes throughout Europe north to central Scandinavia and extends east through Siberia to the far east of Russia; at the eastern extreme of its distribution, including Japan and Korea, it is represented by ssp. osawai Nakane & Sawada, 1956. Here it is generally common throughout southern and eastern England and there are scattered records further north into eastern Scotland. The typical habitat is open deciduous or mixed woodland and parkland where it is associated with a range of agaric fungal fruiting bodies on standing and fallen timber. Adults are active from May to September; they may be found among or around fungi where they burrow large wide tunnels in which they prey on other insects and their larvae, and they may also be swept from grassland in suitable situations; they are diurnal and very fast-moving and will readily take flight when disturbed, they are very powerful and adept fliers and may quickly escape a sweep-net, on one occasion we observed a specimen flying very skilfully from end to end of a 12mm diameter tube, turning in flight without brushing the side of the tube. Larval development occurs among fruiting fungi where they consume mycelia and soft gill-tissue, and they are thought to overwinter in this stage, pupating in the host material in the spring.
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The large size and general appearance is sufficient to make this species unmistakable even in the field. 6-8mm. Head and mandibles entirely shiny black, palps and antennae orange; head very large; a little wider and longer than the pronotum, weakly convex and very sparsely micropunctured, temples long and rounded, eyes weakly convex and almost round, antennae inserted laterally between the eyes and the outer margin of the mandibles. Mandibles strongly protruding; long, sharp and simply acute at apex. Pronotum orange, transverse with distinct anterior angles and rounded posteriorly, shiny, glabrous and lacking punctures. Scutellum black. Basal half of elytra extensively pale, posterior half black, each with three longitudinal series of strong punctures, various scattered large punctures and a raised sutural margin. Abdomen strongly bordered and each tergite with a distinctive curved lateral line, the basal four or five tergites orange, distal tergites black, all glabrous with very fine transverse microsculpture. Legs robust, femora unarmed, tibiae with longitudinal series of fine setae and otherwise pubescent, each with strong apical spurs. Tarsi 5-segmented, the terminal segment much longer than the others, claws smooth and strongly curved, without a basal tooth.
OXYPORINAE Fleming, 1821
This monogeneric subfamily includes about one hundred species of the genus Oxyporus Fabricius, 1775; the former genus Pseudoxyporus Nakane & Sawada, 1956 being reduced to a subgenus of the present group. They are very distinctive within the family due to the form of the antennae, with the last six segments being variously transverse and forming an elongate club (although in several foreign species they are almost filiform), the long, sharp and overlapping mandibles which project in front of the head and the form of the palps which have the terminal segment securiform. They are robust species with a large head; the strongly convex eyes are placed anteriorly in front of very long temples, a quadrate to transverse pronotum and elytra which lack distinct striae but generally have a strongly punctured sutural stria and various other partial striae, foveate punctures or other impressions. Most are vividly coloured, the head is usually dark and the pronotum, elytra and abdomen variously yellow, red and black patterned although they may be entirely black e.g. O. mannerheimii Gyllenhal, 1827 or with the forebody and elytra entirely red as in O. procerus (Kraatz, 1879). They occur in the New World, the Palaearctic, Oriental and African regions; 16 are Neotropical and 14 Nearctic and the greatest diversity is in eastern Asia, only two species are widespread across Europe of which one, O. rufus (Linnaeus, 1758) extends into the U.K. A further species, the Eurasian O. mannerheimii Gyllenhal, 1827, occurs only very rarely in central and northern Europe. The Japanese O. japanicus Sharp, 1889 is unusual in displaying parental care. Adults occur in the summer; they disperse by flight and are associated with fungal fruiting bodies into which they burrow and form egg chambers for oviposition. All species so far studied are obligate fungivores associated with various Agaricales, Boletales and Polyporales and both adults and larvae feed on the spore-producing tissues although adults are also known to be predatory, consuming larvae and other insects occurring on their fungal hosts. Species vary in the range of fungal-associations with some being restricted to a single genus e.g. the nearctic O quinquemaculatus LeConte, 1863 on species of Pluteus Fr.(Agaricales, Pluteaceae) while O. rufus (Linnaeus, 1758) is widely polyphagous on the fruiting bodies of agaric fungi. In general the larvae have a narrower range of hosts and are restricted to a very few species. Most have a very rapid life-cycle, two or three weeks from egg to adult, which is an adaptation to the often short-lived appearance of the host material, but in northern temperate regions some species overwinter as larvae. Some species of Tachyporinae which are also associated with fungi are similarly coloured but readily distinguished by the characters given above.