STAPHYLINIDAE Latreille, 1802

Rove Beetles

The largest British family. Rove beetles can be found in almost all habitats, and are among the most frequently encountered beetles.

With the recent addition of the Scydmaenidae (see below) this huge group is now generally acknowledged to be the largest family within the coleoptera as well as in the whole Animal kingdom; around 63000 species (estimates vary) have been described, and while this is a large figure in absolute terms estimates suppose that more than 75% of tropical species remain undescribed and there are many thousands of specimens in museums awaiting description; about 400 species are added each year, again an impressive number, but making the description of the entire family a daunting task, even if only in terms of the time it will involve, and assuming that enough money and specialists are available. In 1987 it was estimated that about 47000 species had been described (including about 8400 pselaphids and 1200 Scaphidiinae), and so while progress since that time has been impressive, it is clear that in these terms it will be many years before we see anything like a complete list. As with any large group the classification has been evolving over the years and some groups formerly considered as distinct families are now included as sub-families e.g. Empelidae, Dasyceridae, Scydmaenidae, Pselaphidae and Scaphidiidae, while the Microsilphinae and Glypholomatinae were formerly tribes of the Silphidae.

Classification

The present situation is of course ongoing, and often controversial, but a system which is widely considered serviceable divides the family into 32 subfamilies, about 100 tribes, some of which are grouped into supertribes, and about 3200 genera. The subfamilies fall into four phyletic lines which may well become distinct families in the future:

Suborder:      POLYPHAGA Emery, 1886

Superfamily:  STAPHYLINOIDEA Latreille, 1802

Subfamilies:  19

Genera:         Approx. 270

Species:        Approx. 1120

Size:              0.9-30mm

OMALIINE GROUP

Glypholomatinae Jeanell, 1962

Microsilphinae Crowson, 1950

Omaliinae Macleay, 1825

Empelinae Newton & Thayer, 1992

Proteininae Erichson, 1839

Micropeplinae Leach, 1815

Neophoninae Fauvel, 1905

Dasycerinae Reitter, 1887

Protopselaphinae Newton & Thayer, 1992

Pselaphinae Latreille, 1802

Scydmaeninae Leach, 1815

OXYTELINE GROUP

Trigonurinae Reich, 1865

Apateticinae Fauvel, 1895

Scaphidiinae Latreille, 1807

Piestinae Erichson, 1839

Osoriinae Erichson, 1839

Oxytelinae Fleming, 1821

STAPHYLININE GROUP

Oxyporinae Erichson, 1839

Megalopsidiinae Leng, 1920

Steninae Macleay, 1825

Euaesthetinae Thomson, C.G., 1859

Solierinae Newton & Thayer, 1992

Leptotyphlinae Fauvel, 1874

Pseudopsinae Ganglbauer, 1895

Paederinae Fleming, 1821

Staphylininae Latreille, 1802

TACHYPORINE GROUP

Phloeocharinae Erichson, 1839

Olisthaerinae Thomson, C.G., 1858

Tachyporinae Macleay, 1825

Trichophyinae Thomson, C.G., 1858

Habrocerinae Mulsant & Rey, 1877

Aleocharinae Fleming, 1821

Around the World

Staphylinidae is the largest family in the U.K. as well as in many other European countries, and it is also, with more than 4000 species, the largest in North America. Some idea of the extent of the family, as recently listed, may be appreciated by considering the following numbers of species from various regions: Europe >4000 of which The U.K. >1000, Central Europe about 2000, Scandinavia >1200, Australia about 2500, New Zealand about 1000, and even relatively recently colonized islands tend to have a diverse fauna e.g. there are more than 100 species in Hawaii.  And these figures are likely to greatly increase. Frankly there is little point in discussing the world distribution of the family as it is such a bewilderingly wide subject, but some consideration of this aspect will be discussed briefly under the subfamily headings given below and more extensive information will be given in the pages devoted to particular groups or species. Many fossil specimens have been collected and some of these are of modern species so they can shed light upon their modern distribution. Pleistocene fossils are known from Europe and North America while Oligocene fossils are more widespread; from Dominican and Baltic amber and from shales in Europe and North America. Cretaceous and lower Jurassic deposits have also produced Staphylinid fossils. The most ancient of such fossils, from Virginia (U.S.), is from the upper Triassic, more than 200 million years old. Most of these fossils resemble modern groups.

Description

The vast majority of species are instantly recognizable as staphs; they are generally elongate and slender with short elytra and an exposed and flexible abdomen. Some subfamilies are atypical e.g. Scaphidiinae or Omaliinae, but with a little experience these also become obvious. Staphylinids range in size from less than a millimetre to about 40 mm although for the purpose of identification size is often a poor guide as many species are able to ‘telescope’ the abdomen and so may appear longer or shorter than usual, this telescoping often occurs as set specimens are drying. The majority of species are small, <6mm, and some subfamilies are composed entirely of small species e.g. Micropeplinae or Proteininae, or mostly so e.g. Aleocharinae. Given the huge diversity it might be surprising that there are no larger species, but size is a reflection of the lifestyle of most species; the form and flexibility of the body enables staphs to live in physically constrained environments that would not be available to other beetles, and so it follows that an increase in size or rigidity would not be adaptive. By no means do all groups have the short elytra typical of so many, and in general, beyond the elongate and parallel to fusiform habitus, most staphylinid features vary so much that a more detailed description of the species is better given at the subfamily level e.g. the most developed eyes are seen in Steninae or some Quedius (etc.), but beyond this they vary in size and convexity, and many cavernicoles and myrmecophilous have rudimentary eyes or lack them altogether. Some groups e.g. Omaliinae also have ocelli. Similarly while many species possess well-developed hind wings and disperse by flight, many specialized species living on seashores, caves or in the soil have reduced or lack them entirely. Tarsal development is also very variable with all combinations from 5-5-5 to 3-3-3 being represented. Those species with short elytra are generally very agile and flexible, but in many cases this advantage is traded for a susceptibility to desiccation, and in many such species the abdomen has evolved to (partially) counter this e.g. in some Paederinae, Osoriinae, Euasthetinae and, particularly, Steninae, the abdominal tergites, sternites and paratergites are fused into complete rings. Typically the antennae are 11-segmented and filiform, tending towards a moderate club in some groups and distinctly clubbed in some Steninae. Most species are drab and dark but some groups include bright yellow to red colours e.g. Tachyporinae or Oxyporinae, and many are strongly metallic e.g. in Steninae and Paederinae, but some truly strikingly coloured species are to be found in the Staphylininae. The only group of insects likely to be confused with the staphs are the Dermaptera (earwigs) but these have opposable abdominal appendages and many more antennal segments.

Ecology

Many species develop in temporary habitats e.g. decaying plant and animal or fungal matter, dung or by temporary pools, and so, in general, the immature stages tend to grow rapidly, in days or weeks, while the adults tend to be long-lived. Staphylinid eggs are round, elongate or ovoid and while many are smooth, some have characteristic microsculpture etc. so that identification to certain groups is possible. The larvae are generally elongate and flattened with well-developed legs; they often resemble carabid larvae but differ in the form of the legs i.e. those of carabids are six segmented and often have two claws while those of staphs are five segmented and always, so far as is known, have a single claw. In staphs the urogomphi are almost always articulated and one or two segmented, any with immovably attached urogomphi are very distinct from carabid larvae; in carabids the urogomphi are not segmented and are immovably fixed to the ninth segment, in some there are articulated urogomphi but in such cases they always have more than two segments. In some groups, more especially Paederinae and Staphylininae, the head is heavily sclerotized and separated from the thorax by a distinct neck. Pupae are obtect (with appendages mostly inside the body), dark and sclerotized in the Staphylininae but in all other groups they are exarate (with the appendages mostly on the surface) and soft or only lightly sclerotized. The prepupal stage in many groups e.g. Steninae, some Paederinae and most Aleocharinae spin a silken cocoon in which to pupate. Staphs occur in such a wide range of habitats that it seems futile to make a list; the majority are probably scavengers while a significant number, especially of the larger species, are active predators of other insects and their larvae, and a few are parasites; parasitic species occur e.g. in the Aleocharine genera Aleochara, Baryodoma and Coprochare, they are external parasites of Diptera larvae enclosed within the puparium, and to facilitate this mode of life the females often oviposit in the soil beneath infected plants. Most attack subterranean pupae but other lifestyles have been documented e.g. Aleochara (Mesochara) valida ( which at 7-13mm is the largest of the genus and probably the largest of all Aleocharinae) is a parasite of the syrphrid Volucella marginata which develops in decaying cacti leaves and stems. Many of these parasites pupate outside the host puparium but sometimes, as in the Nearctic Barydoma bimaculata Gravenhorst, development is completed entirely within, the adults emerging from the puparium. Many immature stages predate other insects and larvae, particularly those of Diptera, these are typified by species of Philonthus, Quedius and Platydracus etc. which generally occupy the same habitats as the prey e.g. dung or carrion, and they are generally very aggressive and active. While staphs occupy just about all habitats many favour moist environments e.g. marginal situations and reed beds, and many will quickly appear at temporary pools in dunes and woodland but none are properly aquatic; many species are adapted to hunt or disperse on the water surface e.g. some Steninae, Paederinae and Oxytelinae are able to walk back to the margin when they accidentally end up on the water surface. Many hundreds of species, in several subfamilies, live only on the seashore and these, even in the U.K., often appear in great abundance. Sweeping vegetation, especially grassland, will always produce staphs, more especially Tachyporinae, Omaliinae, Aleocharinae and Oxytelinae, and some of these will be found in abundance on flowerheads. Decaying leaf-litter, especially on woodland margins, among grass tussocks and in marginal situations can be rich in species, and in fact any decaying organic matter is worth sampling; fallen fruit, dung, carrion, mammal and bird nests and fungi - especially large terrestrial fruiting bodies - can host many thousands of specimens, especially in the autumn. Decaying wood and debris collected from under bark can produce a wide diversity of species, and searching through debris from recently deserted nests of social insects is often rewarding. Many species can also be found in caves and among subterranean fungi and mammal dens. Searching tree-trunks and fungi at night will produce many active specimens and a few are even associated with terrestrial molluscs; staphs have not evolved to prey on molluscs in the same way that some carabids e.g. Cychrus or silphids e.g. Phosphuga have, although many larger species e.g. Ocypus regularly predate them, and some Palaearctic Aleocharinae are parasitic on snails e.g. Zyras sagax Cameron, 1941 has been observed entering the mantle of some pulmonate molluscs and has been assumed to feed on the faeces or mucus within. Apart from sweeping and nocturnal searching some of the best ways to find staphs are by Berlese extraction, tapping likely samples over a sheet or, in the case of dung, immersing it in water, lying down and examining marginal habitats, especially in bright sun when many species will be active, and here it is useful to take a container so that exposed areas of silt etc. can be flooded thus forcing specimens to surface, and trapping. Many species will come to light; properly sited an illuminated sheet may produce thousands of Oxytelinae and Aleocharinae, but many other traps will be productive; carrion traps baited with fish or chicken, pan-traps situated beside dung or carrion, bottle traps baited with just about anything from mushrooms to dry grass, these can be sited in tree hollows or reed-beds etc., fermenting fruit traps can be excellent, and many species can be found at sap runs on damaged trees. In general there is no end to the list of ways to obtain specimens but, apart from a minority of species, most will need to be looked for in moist habitats e.g. we often find Paederus littoralis Gravenhorst, 1802 in abundance on sun-exposed calcareous hillsides in the Chilterns, they are active on grass stems etc. at night but during the day they remain in the soil or under stones where the substrate is always damp.

The feeding habits of staphs are similarly diverse but in a very general sense the four groups outlined above tend to specialize in various ways; fungi, and especially decaying fruiting bodies, will host abundant specimens but many of these, especially the larger ones, feed on the equally abundant insect larvae, particularly those of various Diptera, that are invariably present, and true fungus-feeding (mycophagous) species have mostly evolved in the Tachyporinae, Aleocharinae, Scaphidiinae and Oxyporinae; if carefully observed in the field species of Scaphidium Olivier, 1790 can sometimes be seen ‘grazing’ on tiny fruiting bodies under logs etc. in damp woodland. Many species have evolved to feed on plants and some are known to be significant pollinators of specific hosts; many Omaliinae occur on flowers where they feed on pollen as well as structural parts; some Carpelimus Leach, 1819 species have been reported damaging cucumbers, Osorius Guérin-Méneville, 1829 (Osoriinae) are known to cause damage to turf, and some Aleocharinae are known to be phytophagous e.g. Himalusa thailondensis Pace, Klimaszewski & Center, 2010 has been considered as a possible biocontrol agent of the invasive Skunk Vine. Both the adults and larvae of some Bledius Leach, 1819 (Oxytelinae) feed on diatoms in marginal substrates. Beating spring blossom or the flowers of gorse or broom will invariably produce Aleocharinae. Sometimes the relationship with plants is not straightforward e.g. Central and South American species of the Aleocharine genus Charoxus Sharp are associated with figs; adults are attracted to the flowers and fruits and enter tiny holes made by fig-wasps, the beetle oviposits in the fruit and the larvae develop feeding upon wasp larvae and adults. Most staphs are facultative predators, appearing opportunistically wherever suitable decaying substrate is likely to host Diptera larvae etc., this method of feeding is common throughout most subfamilies but especially Tachyporinae, Pselaphidae, Steninae, Paederinae and Staphylininae. Some species are (of course) specialized e.g. members of the Aleocharine genus Oligota Mannerheim, 1830, and the majority of the Scydmaeninae predate mites, and some members of the Staphylinine genus Erichsonius Fauvel, 1874 specialize in consuming soil-borne nematodes. Some are highly specialized e.g. the tropical Odontolamus fasciatus Sharp, Belonuchus cephalotes (Sharp) and some Platydracus Thomson, C.G., 1858 predate aquatic diptera larvae in water-filled Heliconid bracts, and a species of Hesperus Fauvel, 1874 (a pantropical genus of >200 species which develop mostly in old trees) predates the same insects in bamboo stems. Members of the tropical genus Eulissus Mannerheim, 1830 (Staphylininae, Xantholinini) prey on adult dung beetles.

Social behaviour is known in a few groups where adults construct chambers within the host medium for the protection of developing early stages; some Platystethus Mannerheim, 1830 in dung, and some Bledius in silty or muddy marginal habitats, and the Aleocharine Eumicrota deposits eggs in fungi and remains to guard the developing larvae. Many species, especially in Aleocharinae but also other subfamilies, are inquilines in social insect nests e.g. ants, termites, bees and wasps, these generally have behavioural, chemical or structural adaptations, and sometimes mimic the host e.g. Emus has been reported invading hymenopteran nests in Europe. Neotropical members of the Aleocharine genus Euvira develop among communities of lepidopteran larvae while Nearctic members of the genus develop in oak galls. Adults of Neotropical species of Amblyopinus Solsky, 1875 (Staphylinini, Amblyopinina) occur in the fur of rodents feeding upon fleas etc. and they are transported by adults between nests where the larvae develop, consuming other insects. Many species are adapted in other ways e.g. many inquilines in social insect nests produce chemicals that fool the host into accepting them, thus the Aleocharine Zyras is able to live amongst the ant Lasius fuliginosus, and many marginal Stenus species have abdominal glands which produce the surfactant stenusin, this reduces the surface tension of the water behind the beetle thus propelling it forwards. Stenus also have extrusible mouthparts, the labium and palps being produced forward by internal pressure so enabling them to capture small and illusive prey such as springtails. Adults of many subfamilies e.g. Steninae, Oxyporinae, Paederinae and Staphylininae secrete oral enzymes etc. which allow then to partially digest their food while it is being manipulated by the forelegs and mouthparts; in such species the diet is largely liquid. Adults of the tropical Leistrotrophus versicolor (Gravenhorst, 1806) ‘ambush’ prey, mostly flies, by luring them onto vegetation with a volatile secretion from the abdomen. Many species produce defensive secretions from various parts of the body, Ocypus olens is notorious for releasing fluids from the mouth and abdominal apex, and many Omaliinae and Proteininae possess defensive glands between the seventh and eighth sternites. The powerful toxin pederan is present in the haemolymph of Paederus Fabricius, 1775 and its close allies, it is produced by endosymbionts in some females and passed to the eggs and so is present in all developmental stages, it is a powerful protection against arachnids, although much less effective against insects, and is a well known and powerful human irritant. As many of the larger staphs are voracious insectivores some have been tried as biological control agents in many areas e.g. Tachyporus against aphids in crops, or Aleocharines against mites and horn flies in the United States and root-feeding larvae in Europe but in general without success.

Sexual dimorphism is common among staphs and well-developed in many species; in many Oxytelinae the males possess thoracic or cephalic horns or other modifications, and in many groups the mandibles are more developed in males. In general the proportions of the head and pronotum differ between the sexes and males often have modified pro-tarsi.

Staphylinid identification is still very difficult, even in the U.K., although in many European countries the situation is much better and some foreign works cover much of the U.K. fauna but an ability to translate is essential, particularly of German. Here the situation was greatly improved by the publication of two modern R.E.S. Handbooks, and for some of the subfamilies not covered by these Joy’s 1932 Handbook and an old R.E.S. Handbook remain useful but the Aleocharinae remain problematic and will require a great deal of literature searching before any real progress can be made. The ability to dissect specimens, even of larger species within the Staphylininae, is essential.

UK Subfamilies

ALEOCHARINAE

Subfamily introductions

The following is a brief summary of the subfamilies of Staphylinidae with a particular emphasis on the U.K. fauna but we hope to elaborate upon these notes with sections devoted to each group in greater detail. The U.K. fauna includes about 1150 species, or about a quarter of our coleoptera list, and so anybody embarking upon a serious study of beetles will need to begin sampling and identifying them. The order in which the subfamilies are listed corresponds with the above list, and those not occurring in the U.K. are given in italics.

1.

GLYPHOLOMATINAE

Originally classified as a tribe of the Silphinae this small group includes two genera and about ten species. Glypholoma Jeannel, 1962 includes seven species from Southern Argentina, Chile and Southern Australia. Proglypholoma Thayer, 1997 includes the single species P. aenigma Thayer, 1997 from Chile. They are small and broadly oval, mostly testaceous species with gradually clubbed antennae, long elytra that more-or-less cover the abdomen, and a transverse and convex pronotum. The elytra have distinct punctured striae and the habitus is reminiscent of cucujoid beetles. They are saproxylic and thought to feed on fungal hyphae among fallen timber.

2.

MICROSILPHINAE

Includes only the single genus Microsilpha Broun, 1866. This was originally placed within the Silphidae and then transferred to the Omaliinae but the species are sufficiently distinct to form the present group. They are small species with long elytra, clubbed antennae, sparse and strong punctures across the dorsal surface and the elytra lack striae. Four species are known, from New Zealand, Australia and Argentina. Their biology is unknown and most have been taken in flight-interception traps in forest situations.

3.

OMALIINAE

A large and cosmopolitan family including about 1400 species in 117 genera and 7 tribes. Although widely variable in overall morphology this group is in some sense easily identified by the presence of two ocelli on the vertex of the head at the level of the hind margin of the eyes, a good character but one that often needs to be looked for very carefully. Hence the sometime common name of ‘ocellate rove beetles’. These ocelli probably have no sensory function. Among the European species, and much of the group as a whole, they are fairly typical, albeit diverse, rove beetles; 1.5-7mm and mostly rather broad and flat species, often with long elytra which are only rarely striate, a small head with a broad neck, and filiform antennae which are at most only weakly broadened towards the apex. The tarsi are five-segmented. Beyond our typical fauna the group is very diverse e.g. species of the Nearctic and Japanese genus Brathinus LeConte, 1852 are ant-mimics. The U.K. fauna includes about 70 species in 28 genera and 5 tribes. In general both adults and larvae occur in fungi, leaf-litter, decaying fruit and among moss or under bark etc. A few species are phytophagous, occurring on flowers where they feed on pollen and vascular tissue, and both stages in many groups are believed to be predatory.

4.

EMPELINAE

Includes the single monotypic genus Empelus LeConte, 1861. E. brevipennis Mannerheim, 1852 is restricted to the Nearctic zone, being widespread across North America from Alaska to California. It occurs in leaf-litter, moss and fungi in damp marginal habitats. Adults are small <2mm and entirely testaceous with 11-segmented antennae that bear a distinct 3-segmented club, a 5-5-5 tarsal formula, elytra that completely cover the abdomen and a fine and sparse dorsal punctation and pubescence. Reminiscent of Tachyporinae or Proteininae, but for the long elytra.

5.

PROTEININAE

Includes almost 200 species in 11 genera and 5 tribes. Proteinini Erichson, 1839 occurs throughout the world with the exception of Australasia while the other tribes, which include only a few, mostly monogeneric, genera occur in the Southern Hemisphere. All three genera of the Proteinini occur in the U.K; Megarthrus Stephens is by far the largest with about 120 species and is almost cosmopolitan, Metopsia Wollaston, 1854, with 14 species, and Proteinus Latreille, 1796, with 30 species, are Holarctic. They are small beetles <3mm, characteristically broad with medium-length truncate elytra that cover at least the first abdominal tergite. The head, pronotum and elytra are mostly smooth although the head may be variously sculptured and the pronotum may have a median longitudinal impression. The antennae are 11-segmented with the two basal segments expanded and remainder at most only weakly thickened towards the apex giving the impression of a very indistinct 3-segmented club. The tarsi are 5-segmented or, in some Southern Hemisphere groups, 4-segmented. In some, especially Megarthrus, the pronotum is variously indented, angled or produced laterally or at the anterior or posterior angles, and the clypeus is often characteristically widely emarginate and angled. They occur in fungi, dung, decaying vegetation or among leaf-litter or tussocks. The adults may occur in large numbers, especially Megarthrus in dung, or Proteinus in decaying terrestrial fungi. The larvae are thought to develop in decaying organic material while the adults may be saprophagous, mycophagous or scavengers.

6.

MICROPEPLINAE

This is a small group of about eighty species included in five genera. Most of the species, about sixty, are members of the Holarctic genus Micropeplus Latreille, 1809, of which five occur in the U.K. All are very distinctive; small <3mm, broad and flattened with distinct ridges to the head, pronotum and elytra, the antennae are 8 or 9 segmented with a one segmented club, the elytra are short leaving five or six articulated abdominal segments exposed, and the tarsi are four segmented. In some groups e.g. the monotypic Nearctic genus Kalissus LeConte, 1874 the ridges are confined to the elytra and are variously developed, often convex with fine longitudinal ridges. They occur in decaying vegetation, leaf-litter, fungi, mammal and bird nests and wetland marginal situations.

7.

NEOPHONINAE

includes the single monotypic genus Neophonus Fauvel, 1905. The species N. bruchi (Fauvel, 1905) occurs in forested areas of Argentina and southern Chile. It is probably unique among the family in that it feeds (from analysis of gut-contents) on foliicolous fungi i.e. those that grow on the leaves of vascular plants. Larvae are unknown but the adults show mouthpart and tarsal adaptations presumably associated with specialized feeding. Adults are small, 1.5-2.5mm, dark and very distinctive with very deep posteriorly converging furrows along the frons and vertex of the head, large and convex eyes and massive rounded temples. The pronotum has a deep transverse furrow towards the base and is constricted in the anterior half; the overall appearance of the forebody is rather pselaphine-like. The elytra are very long, although still leaving three or four abdominal tergites exposed, dilated posteriorly and truncate, and each has convex interstices between nine or ten well-impressed and strongly punctured striae. The antennae are 11-segmented with the last three segments a little broader than the others, forming an indistinct club. The habitus is very distinctive.

8.

DASYCERINAE

This small subfamily includes almost twenty species of the single genus Dasycerus Bronginiard, 1800. They occur in Holarctic and Oriental regions; four in North America and only one in central Europe which does not extend to the U.K. In appearance they resemble some Latridiidae, and have variously been classified as such; testaceous with oval elytra that cover the abdomen and have raised longitudinal ridges and punctured striae, heavily sculptured pronotum which is widest at the middle, often angled laterally and strongly narrowed anteriorly and posteriorly, and the head broadly produced in front of small convex eyes. The antennae are 11-segmented with a 3-segmented club, and the tarsi are three segmented. They mostly occur among leaf-litter, fungi and in decaying stumps in wooded environments. Both adults and larvae are thought to be mycophagous.

9.

PROTOPSELAPHINAE

This monogeneric and exclusively tropical subfamily includes eight species of Protopselaphus Newton & Thayer, 1995. All are elongate with moderately long elytra leaving most of the abdomen exposed, a prognathous head broadly extended in front of large and coarsely-faceted eyes and unusual 11-segmented antennae; the two basal segments are expanded and the intermediate ones become progressively more transverse before a distinct three-segmented club. Appropriately named and superficially resembling some pselaphids, they differ in having the elytra longer, at least twice as long as wide, and without basal fovea or depressions, a flexible abdomen which is acuminate apically and the protarsal claws symmetrical and with paired parungeal setae. The tarsi are three-segmented. Nothing is known about their biology.

10.

PSELAPHINAE

Until recently regarded as a distinct family, the group was incorporated into the Staphylinidae by Newton and Thayer in 1995; it is a large group of more than 12000 species in over 1200 genera and six supertribes. The morphology varies enormously but all are small beetles; mostly less than 3.0mm, with short elytra exposing most of the abdomen, a pronotum that is narrower than the elytra and a very variable head. The majority are drab, testaceous to black; those in temperate regions tend to be darker and often have pale markings to the elytra, and they vary from glabrous to quite densely pubescent. Some groups e.g. the supertribes Euplectitae and Faronitae resemble more typical staphs but many have undergone adaptations, sometimes extensively, to their way of life e.g. many species live in caves and have developed very long legs and antennae e.g. the monotypic Nearctic genus Texamaurops Barr & Steeves, 1963, and the many species of the Clavigeritae, all of which are obligate inquilines of social Hymenoptera, have various body parts fused and modified or expanded to form robust plates and huge antennal segments e.g. the British Claviger testaceous Preyssler, 1790 or the truly bizarre Colilodion incredibilis Besuchet, 1991 from Malaysia. The Clavigeritae are distinct among the subfamily; the eyes are diminutive or absent, the antennae often small and recessed into a cavity on the front of the head, the maxillary palps often reduced or appearing to be 1 or 2-segmented and abdominal tergites 4-6 are fused to form a single plate which is depressed in the centre and has specialized glands or ‘trichomes’ that secrete fluids that are attractive to, and consumed by hosts, the various body parts vary greatly in proportion e.g. the pronotum may be broadly transverse as in the Malaysian Pseudacerus Raffray, 1895, or narrow and elongate e.g. in the Southeast Asian Diartiger Sharp, similarly appendage morphology varies widely, the legs are perhaps most developed in some Nearctic Adranes LeConte, 1838. The group is represented in the U.K. by 2 species of Claviger Preyssler, 1790, a Palaearctic genus of 40 species. The remaining groups, although very variable, tend to be distinctive with the dorsal surface characteristically sculpted; many have deep fovea on the vertex between the eyes, on the pronotum, elytra and mesosternum, and the elytra are often longitudinally grooved, most have well-developed eyes, long palps and antennae. The abdominal tergites are distinct, never fused, although they may be depressed, foveate or otherwise sculpted but they never have trichomes. The tarsi are 3-3-3 or 2-2-2. In many groups the maxillary palpi are greatly developed and may be longer than the antennae; they are 5-segmented, which is unique among the coleoptera, although the terminal segment is small and often difficult to see, the basal segment may also be diminutive, the second is long and glabrous, the third variable and the fourth may be hugely expanded, club-like, and is often sexually dimorphic. Males are often distinguished by other characters e.g. antennal development, the proportions of various body parts and the presence of spines or spurs on the legs etc. In many groups the femora are expanded and may be dimorphic. The antennae vary widely, in our U.K. species 11-segmented, but more generally 11, 10, 9 or 3-segmented; they are generally long and modified in some way, often thickened or very long, and usually distinctly clubbed, antennal development is probably most extreme in the Neotropical genus Metopioxys Reitter, 1885 (see M. gladiator Reitter, 1885) where the basal segment is hugely elongate. The U.K. fauna includes 54 species in 19 genera and 4 supertribes. With the exception of Claviger, which occurs in nests of the ant Lasius flavus (Fabricius, 1781), species occur in decaying wood or among debris under bark, in leaf-litter, compost and among decaying organic matter in the soil, some live in marginal situations, including salt-marshes, and some will occur while sweeping vegetation or examining compost samples, specimens regularly occur in Berlese extractions. The British species were keyed out in a 1957 RES handbook by E. J. Pearce, significantly updated in the Entomologist’s Monthly Magazine in 1973 (pp.13-26).

11.

SCYDMAENINAE

Formerly considered as a distinct family but incorporated into the Staphylinidae in 2009 by Grebennikov, V.V. & Newton A.F.; it is a large and cosmopolitan group of about 4500 species in 80 genera. The morphology varies widely but with a little experience most will be readily recognized; they are elongate to broadly oval and small <5mm, the European fauna from 0.7 to 2.3mm. The head structure varies but the antennae are 11-segmented with a variable 3-segmented club, and inserted in front of or between the eyes, the maxillary palpi are 4-segmented, often well-developed with the third segment enlarged and the fourth small. The eyes vary from large, occupying the whole side of the head e.g. in some Scydmoraphes Reitter, 1891, to very small as in some Euconnus Thomson, C.G., 1859 where the temples are correspondingly large. The pronotum is generally quadrate to weakly transverse or elongate, usually convex and smooth but for various basal fovea or impressions. The elytra are entire, covering the abdomen or leaving only the pygidium exposed, convex and usually smooth, often with basal impressions but lacking striae, the epipleura are smoothly reflexed and not delimited from the lateral margin by a border. The legs vary widely but are usually robust; the tarsi are 5-segmented. Abdomen with six ventrites. The colouration varies from testaceous to black, many have red markings to the elytra and some are distinctly metallic, all are to some extent, often densely, pubescent. Identification often relies on dissection but even the tiny species have well-sclerotized and robust genitalia. Many species superficially resemble ants, with a constriction between the head and pronotum, and the pronotum and elytra; the association with ants is well documented and about 120 species of 20 genera have been recorded associated with 45 species of ants in 28 genera, and about 20 are known from termite nests. Most species occur in damp environments; among moss and leaf-litter, compost, under stones and among dense vegetation, many are saproxylic; living among decaying fungoid wood and wood debris, and some occur in mammal nests, some are known to feed upon Oribatid mites, with mouthparts adapted to scraping through or cutting the mites thick cuticle. About 500 species occur in Europe and the U.K. fauna includes 32 species in 9 genera and 4 tribes; the wider world diversity of some of our genera is surprising: Eutheia Stephens, 1830 includes 35 Eurasian species, Scydmaenus Latreille, 1802 includes >730 species worldwide of which only 12 are Nearctic, Cephennium Müller & Kunze, 1822 includes >130 mostly Palaearctic species, Euconnus Thomson, C.G., 1859 is cosmopolitan with >2500 species, and Stenichnus Thomson, C.G., 1859 is cosmopolitan with >200 species.

12.

PHLOEOCHARINAE

This is a small subfamily of 7 genera and 52 species. Two genera are Palaearctic: Charhyphus Sharp, 1887 with 5 species, and Phloeocharis Mannerheim, 1830 with more than 30, this last being most speciose in mountainous areas around the Mediterranean. Vicelia Moore & Legner, 1973 includes one Nearctic species and one from Asia. The monotypic genera Ecbletus Sharp, 1887 and Dytoscotes Smetana & Campbell, 1980 occur in America while the monotypic Phloeognathus Steel, 1953 is from New Zealand. Pseudophloeocharis Steel, 1953 includes 6 Australasian species. The group is poorly defined and species are generally best separated from local faunas by a combination of characters. The species are small, cylindrical and rather fusiform, resembling some Tachyporinae (etc.) but distinctly, and sometimes densely, pubescent, they lack ocelli and have filiform, often gradually thickened, antennae, and five segmented tarsi. They possess several unique, if obscure, characters; the form of the hypopharynx is distinctive, the procoxae lack a mesal groove, abdominal tergites 4 and 5 have a pair of circular ‘combs’ and the metatrocanters are long; about one-third the length of the coxae, in e.g. Oxytelinae they are relatively shorter, about one-fifth the length. Our single U.K. species, Phloeocharis subtilissima Mannerheim, 1830 is distinctive on overall size and morphology. Species occur under bark or among logs and litter in damp forest environments.

13.

OLISTHAERINAE

Includes only two species of the single genus Olisthaerus Dejean, 1833. Both occur sporadically throughout Europe but neither extends into the U.K., they are found under the bark of dead conifer trees in old forested areas.  They are small species resembling Phloeocharinae or Piestinae; elongate and parallel-sided with a dark head and elytra, and red pronotum and abdomen; the elytra have unpunctured longitudinal striae and scattered fine punctures. The eyes are small and placed in front of long temples, the antennae 11-segmented and filiform and the tarsi five-segmented.

14.

TACHYPORINAE

This is a moderately large subfamily of more than 1500 species included in forty genera and five tribes. Three of these tribes are small; Vatesini Seevers, 1958 includes two genera of Neotropical myrmecophilous species, Deropini Smetana, 1983 includes the single Palaearctic genus with about twenty species of Derops Sharp, 1899, and the Palaearctic Megarthropsiini Cameron, 1919 includes 20 species in four genera. The remaining two tribes are speciose and cosmopolitan but because in each case most of the species are included in only a few large genera the U.K. fauna is quite typical of the group as a whole e.g. Tachyporini Macleay, 1825 includes Tachyporus Gravenhorst, 1802 with >130 species, Tachinus Gravenhorst, 1802 with >230 species, Sepedophilus Gistel, 1856 with >350 species and Cilea Jacquelin du Val, 1856 with >20 species. The Mycetoporini Thomson, C.G., 1859 includes Lordithon Thomson, C.G., 1858 with >100 species, Mycetoporus Mannerheim, 1830 with >100 species and Bolitobius Leach, 1819 with >30 species. About 65 species have been recorded from the U.K. All are fusiform and very distinctive with the abdomen strongly narrowed towards the apex and the head retracted into the thorax, the head is transverse, narrowed in front of the eyes and with small, usually not visible, temples. The antennae are 11-segmented and inserted under the lateral margin of the head, usually in front of the eyes, and outside the base of the mandibles. The pronotum and elytra are smooth, without distinct sculpture, and have scattered sensory setae, the placement of which is diagnostic in some groups. Most are shiny and more-or-less glabrous but a few are pubescent e.g. Sepedophilus species. Colouration varies from black to drab testaceous or brown but there are many brightly coloured species e.g. among Cilea and Tachyporus. Many are common or abundant among fungi, decaying vegetation and wood or, in the warmer months, on umbel flowers or among vegetation generally.

15.

TRICHOPHYINAE

A small family of about 15 species included in the single genus Trichophya Mannerheim, 1830. Most occur in the Western Palaearctic and one of these, T. pilicornis (Gyllenhal, 1810), is adventive and now widespread in the United States, having been first recorded there in 1933. Three species are native to North and Central America. The species are associated with fungi, moss, leaf litter and wood debris in wooded situations and parkland etc. They are all small, 3-4 mm, and resemble Tachyporinae (fusiform) but the antennal structure is unusual; the two basal segments are large while the others are very thin with a ring of stiff setae around the apex of each, similar to those seen in Habrocerinae, see below. They differ from Habrocerus in having transverse meta-coxae; our single U.K. species is distinct in the form of the pronotum; here it is broadest across the middle whereas in Habrocerus it is broadest across the base. 

16.

HABROCERINAE

This is a small subfamily containing 2 genera and 26 species. Nominocerus Coiffait & Saiz, 1965 includes 6 species from southern Chile and southern Argentina. Habrocerus Erichson, 1839 is a Holarctic group (with 3 Nearctic species) of 20 species that is now much more widespread due to the spread, owing to human activity, of the widespread H. capillaricornis Gravenhorst, 1806, this species was first recorded from the United States in 1931 and has since spread to South America, Tropical Africa, Southeast Asia, Australia and New Zealand; it is also the only species recorded throughout much of Europe, including the U.K., but other species occur in North Africa, The Middle East, Greece and Turkey etc. and there is a Canary Island endemic, H. canariensis Assing & Wunderle, 1965. All species are associated with decaying leaf litter, fungi, wood debris and bark in woodland etc. They resemble small Tachyporinae but differ in the antennae which are long and slender and have rings of long setae around the apex of most segments; this feature is also seen in Trichophyinae (above) but these are distinct in having the meta-coxae transverse, in the present group they are triangular. The head, pronotum and elytra are smooth; without coarse punctures or sculpture and the whole body has prominent lateral setae. All tarsi are five segmented.

17.

ALEOCHARINAE

This is the largest of the staph subfamilies with about 13000 described species in more than 1150 genera and about 50 tribes although these figures are increasing each year and only suggest the true diversity of the group; many thousands of species and numerous higher taxa remain undescribed from around the world, especially in tropical regions where diversity is likely to be greatest. With the exception of Europe, or rather much of central Europe, there are no modern identification guides to the group; European guides cover the U.K. fauna but need to be translated from German and the only guide in English is that of Joy from 1932 which is useful only for certain groups; it is highly comparative, relies on often vague line-drawings and does not include genitalia figures which are absolutely essential for most genera. For U.K. workers identification involves obtaining and researching many papers but even so these will be found to be of varying usefulness and many are out of date. Coleopterists in the U.K. eagerly await the staph volume of Andy Duff’s ‘Beetles of Britain and Ireland’. As things stand, unless a good reference collection is available to those with a certain expertise in the group, it is worth keying out the more distinctive species in Joy and then consulting a checklist to see how relevant the identification might be, although it must be said that even referencing Joys nomenclature to the latest checklist can be a nightmare, and the majority of the specimens will need to be stored for later examination. So far as the U.K. fauna is concerned they may be recognized by the antennal placement; on top of the head more-or-less at the level of the anterior margin of the eyes, but many species from further afield lack this feature, the antennal insertions being placed further back between the eyes. A more esoteric character that seem to be shared by the group as a whole are the large, complex and articulated lateral lobes of the aedeagus. Various larval characters are also unique to the subfamily. Adult morphology varies greatly; at less than 1mm they are among the smallest of insects but they only rarely exceed 10mm and most are between 3 and 5 mm in length. Most are drab, testaceous to brown or black and a few have pale markings or are strikingly coloured. Many are ‘typical’ staphs i.e. elongate and rather parallel-sided or fusiform, with a rounded head and pronotum and short elytra leaving most of the abdomen exposed, but beyond this the variation is huge, even among U.K. species. Tarsal formula is very variable and sometimes used to delimit tribes, it is generally crucial to identification but often the individual segments are near-impossible to see, even when manipulating specimens before they are set. In order to appreciate the variation within the group it will be necessary to spend a few hours on google as the U.K. list will not provide this. This discussion may seem rather pessimistic but from somebody who has spent many, many hours, and not without some success, it seems to be more frustrating each time I try a new specimen. The time may well have been better spent learning German.

Many species are general scavengers and/or predators among decaying vegetation, leaf-litter and soil-borne organic matter, several are associated with fungal spores, mycelia and fruiting bodies both above and below ground, growing or decaying, and many are inquilines in the nests of ants and termites, some are saproxylic and some are associated with dung, and they form a diverse group of intertidal and sand-dune species. Some members of Aleochara are parasites of dipteran pupae, and others parasitize fig wasps. They are likely to occur in almost any habitat and there are many examples, worldwide, of specialization.

18.

TRIGONURINAE

Includes ten species of the single genus Trigonurus Mulsant, 1847; seven are Nearctic, two occur in China and there are two Western Palaearctic species: T. asiaticus Reiche, 1866 from Asia Minor, and T. mellyi Mulsant, 1847 from the European Alps. All are saproxylic and associated with conifer bark. They are small, 3-5mm, elongate species resembling Omaliinae with long elytra, leaving four or five abdominal segments exposed, which have strongly punctured striae, and a parallel-sided pronotum with rounded anterior angles and deep and wide laterobasal fovea. The colour varies from testaceous to dark brown, and the antennae are filiform, lacking any expanded terminal segments.

19.

APATETICINAE

Includes two genera and twenty-five species. All occur in the eastern Palaearctic, including Japan, and Southeast Asia, and the widest diversity is in tropical areas. Apatetia Westwood, 1848 includes nineteen species mostly from Southeast Asia while Nodynus Waterhouse, 1876 includes six eastern Palaearctic species. These amazing staphs look very much like small silphids; broad and shiny with transverse pronotum rounded and produced at the hind-angles. The antennae are eleven segmented with the last six segments pubescent and expanded to form a gradual club. The tibiae are grooved or keeled. For a very convincing miniature silphid see the Java species A. semiviolacea Fauvel, 1904.

20.

SCAPHIDIINAE

This is a large subfamily of about 1500 species included in almost 40 genera. Formerly a distinct family, the appearance is unique with a compact body and almost entire elytra which vary greatly in colour but temperate species tend to be mostly black with various red or yellow markings. The appendages are long and thin; the antennae are unusual in having the last five or six segments modified; either thickened to form an elongate club or with each variously expanded internally. The mouthparts are also unusual within the family in being hypognathous. They occur mostly in wooded habitats and both adults and larvae are fungivores.

21.

PIESTINAE

Includes seven genera and more than a hundred species of mostly saproxylic, mycophagous species, some of which have preferences for particular types of wood. The Holarctic and Oriental genus Siagonium Kirby & Spence, 1815 includes >20 species of which one, S. quadricorne Kirby, 1815, occurs in the U.K. More than half the species are included in the Neotropical genus Piestus Gravenhorst, 1806, many of which develop in decaying cacti and succulents. The species are parallel-sided and flattened, often living beneath closely-fitting bark, with 11-segmented antennae inserted laterally in front of the eyes under an expanded margin of the frons. The pronotum and elytra lack ridges although the elytra may have deep and unpunctured longitudinal striae which give an obscure ridged effect. The head is transverse and often deeply sculptured and some species display pronounced sexual dimorphism with the head and/or mandibles greatly developed in males. The anterior coxae are characteristically small and globular, and the abdomen long with six visible sterna and a single pair of paratergites on segments three to seven. In species of Siagonum tergites two to five have an oblique line from the base to the lateral margin. Several extinct fossil species are known from early Cretaceous deposits in China.

22.

OSORIINAE

Although a large group of more than 2100 species in about 100 genera they occur mostly in tropical and sub-tropical areas and so remain only poorly understood; only about 15 species of 7 genera occur in the Nearctic, at least one of which is a Neotropical adventive, and a single species occurs in central Europe; Thoracophorus corticinus Motschulsk, 1837 is rare in decaying trees alongside the ant Lasius brunneus;. It is small, 2.5mm, broad and flat with prominent longitudinal carinae to the head, pronotum and elytra. Most of the group are saproxylic although some occur in leaf-litter, terrestrial fungi and one species, the Nearctic Eleusis pallida LeConte, was found to be abundant both as adults and larvae in human graves in sandy soil. Members are characterized by the form of the abdomen which is parallel-sided and lacks sutures on the dorsal surface, being either flattened with a single lateral suture, or completely fused and cylindrical, as seen in some Stenus, in dorsal view the abdomen appears smooth, hence the common name of ‘Unmargined Rove Beetles’. The only other staph genus with a fused abdomen is Palaminus Er. (Paederinae) but here the terminal segment of the maxillary palps is as long as the penultimate, in the present subfamily it is smaller.

23.

OXYTELINAE

A large subfamily of more than 2000 species in about 50 genera and 5 tribes: Carpophilini Heer, 1839, Deleasterini Reitter, 1909, Oxytelini Fleming, 1821, Thinobiini Sahlberg, J., 1867 and Euphaninini Reitter, 1909, another tribe is sometimes recognized, the Blediini Adam, 2001, which includes Bledius and another, non-British genus, all are represented in the U.K. Although diverse the members soon become obvious. Some resemble Omaliinae but in all cases they lack ocelli. They are small, 1.5-10mm, and robust beetles; parallel-sided and mostly drab, brown to black and sometimes with paler markings. The head is transverse and flat, often with prominent eyes, with the antennae inserted on the side margins under an expanded lateral margin so that the insertions are visible from above, and usually with large, often prominent, mandibles. The pronotum is quadrate to transverse and varies from smooth to longitudinally furrowed, in some e.g. Carpelimus, there are other impressions, typically a sub-basal transverse or arcuate furrow, the surface is flat to convex and variously microsculptured and/or pubescent, and the lateral margins tend to be simply curved. Distinguished from the Paederinae by the transverse meso-coxae, and from the Staphylininae by the antennal placement. The elytra are short to medium in length and smooth to variously punctured or longitudinally furrowed. Uniquely they possess a pair of defensive glands opening onto the ninth abdominal tergite. The tarsi are 2-2-2, 3-3-3, 4-4-4 or 5-5-5. Sexual dimorphism is common, often displayed in the relative proportions of the head and pronotum but sometimes the males have cephalic or thoracic horns or are otherwise modified. They occur in a wide range of habitats; dung, fungi and decaying vegetation generally, and many genera are associated with wetlands e.g. some Bledius are adapted for burying into wet marginal sediments. Some Platystethus and Bledius have evolved parental care. Many species come to light, often in large numbers. The U.K. fauna includes 15 genera and about 100 species. The family includes several large genera, members of which occur in the Britain, and so a familiarity with or fauna will enable much of the wider world fauna to be recognized, as the following list shows:

Oxytelus Gravenhorst, 1802 includes more than 200 species worldwide which occur in a wide range of habitats.

Carpelimus Leach, 1819 includes more than 400 mostly wetland marginal species.

Platystethus Mannerheim, 1830 includes about 50 species which occur mostly in dung or decaying vegetation.

Anotylus Thomson, C.G., 1859 includes about 360 species, mostly associated with dung.

Thinobius Kiesenwetter, 1844 includes more than 120, mostly Western Palaearctic species.

Ochthephilus Mulsant & Rey, 1856 includes more than 50 Holarctic and Oriental species, mostly associated with wetland margins.

Thinodromus Kraatz, 1857, formerly a subgenus of Carpelimus, includes about 80 species, mostly associated with wetlands.

Bledius Samouelle, 1819 includes more than 450 mostly wetland marginal species.

On the other hand some of our genera are more modest e.g. the Holarctic genus Manda Blackwelder, 1952 includes only three species.

24.

OXYPORINAE

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 transverse and forming an elongate club, 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, and quadrate to transverse pronotum and elytra which lack distinct striae. Most are vividly coloured, the head is usually dark and the pronotum, elytra and abdomen variously yellow, red and black patterned. They occur in the New World, Europe, Africa and Asia, 16 are Neotropical and 14 Nearctic and the greatest diversity is in eastern Asia, only two species occur in central Europe of which one, O. rufus (Linnaeus, 1758) extends into the U.K. 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 lay eggs. Both larvae and adults feed exclusively on fungi. Some species of Tachyporinae which are also associated with fungi are similarly coloured but distinguished by the distinctive characters given above.

25.

MEGALOPSIDINAE

Includes more than 150 species of the single genus Megalopinus Eichelbaum, 1915, it is a pantropical group although two species extend north into the United States. They are small species with very large and convex eyes and a deeply emarginate labrum which is reduced and hidden so that only a pair of very thin processes is visible. The head lacks ocelli and the antennae, which have a two- or three-segmented club, are placed on the vertex in front of the eyes. The mandibles are prominent; long and curved before a sharp apex. The tarsi are 5-segmented. All species are associated with fungi and decaying vegetation and logs in forested areas.

26.

STENINAE

This is a huge subfamily of almost 3000 described species included in two genera, the vast majority of species being in the genus Stenus Latreille, 1796. As a group they are the most instantly recognizable subfamily; the large convex eyes which often occupy the whole side of the head, short and clubbed antennae and narrow cylindrical body are distinctive. More than 70 species occur in the U.K. and both genera are represented; Dianous Leach, 1819 by the single species D. coerulescens (Gyllenhal, 1810). Most of these are diurnal predators occurring in marginal habitats while a few occur in grassland environments.

27.

EUAESTHETINAE

This is a large group of more than 750 species included in 26 genera and 6 tribes which has variously been considered as a tribe of the Steninae. Our U.K. species are included in the largest tribe, the Euaesthetini Thomson, C.G., 1859, a cosmopolitan group of 12 genera. Two more tribes occur in northern temperate regions; Fenderiini Scheerpeltz, 1974 with one Nearctic and one Holarctic genus, and the Nordenskioldiini Bernhauer & Schubert, 1911 with 3 Holarctic genera and one confined to the Himalayas. Stanaesthetini Bernhauer & Schubert, 1911 includes four tropical genera, and both the monogeneric Alzadaesthetini Scheerpeltz, 1974 and the Austroesthetini Cameron, 1944, with four genera, occur in southern hemisphere temperate regions. By far the greatest diversity is in tropical areas; 22 species in 5 genera are known from The United States, and almost 70 species in 5 genera are known from Europe although most of these, about 60 species, are in the single genus Octavius Fauvel, 1873, a pantropical group of about 220 species which extends into South Africa and Europe. The U.K. fauna includes four species in two genera although one of these, Edaphus beszedesi Reitter, 1914, is adventive from mainland Europe. Our two genera represent part of a much wider diversity; Euaesthetus Gravenhorst, 1806 is Holarctic and includes about 40 species, 20 of which are Nearctic, Edaphus Motschulsky, 1857 includes more than 350 species and is almost cosmopolitan, being absent from various parts of South America.  The species are small, generally <2mm and rather parallel-sided, the head often with various impressions between the eyes and the pronotum cordate, or at least broadest in the anterior half, and variously impressed towards the base. The eyes are relatively small and placed towards the base of the head and so the cheeks are long and the temples almost absent.  The antennae are short, slender and have a two-segmented club (three-segmented in some non-U.K. species); they are inserted on the dorsal surface well in front of the eyes and within the base of the mandibles. This antennal placement along with the small size and antennal club will identify the group within the U.K. fauna. The abdomen is strongly bordered and generally tapering from the basal third to the apex. The tarsi are 4-4-4 or 5-5-5 although in some tropical genera it is 5-5-4. They occur among decaying vegetation in a wide range of damp situations, often marginal, including salt marshes, but also among leaf-litter and tussocks in woodland situations, and they often turn up in samples of flood refuse.

28.

SOLIERIINAE

Includes the single monotypic genus Solierius Bernhauer, 1921, S. obscurus (Solier, 1849) occurs in forested areas of Chile. Nothing is known of its lifestyle. A further four species of the extinct genus Prosoleirius Thayer et.al., 2012 are known from mid Cretaceous amber deposits from various old world locations and this wider diversity and distribution suggests the modern species is a relict.

29.

LEPTOTYPHLINAE

This is a large group of about 850 species in 45 genera and 6 tribes. They are tiny insects; <1.8mm, eyeless and wingless. Most are very elongate and appear testaceous due to their lacking pigment, with a large, elongate head and 11-segmented antennae which broaden gradually towards the apex, the pronotum is often broadest at the anterior angles and narrowed to the base, the elytra are small and narrow and the abdomen 7-segmented, long and strongly bordered, the entire body is pubescent and has many erect sensory setae. The tarsi are 3-segmented. They occur in deep leaf-litter or among subterranean organic matter, possibly feeding upon springtails and mites. They never leave the soil. The group is almost cosmopolitan and is most diverse in temperate regions e.g. Mediterranean Western Palaearctic, California and Chile; more than 150 species in 11 genera occur in Italy, 19 species in 11 genera occur in the Nearctic including Cuba, and a single species has been recorded from Alaska. They tend to be very rare in collections due no doubt to the difficulty in finding them; the most effective methods seem to be soil flotation and Berlese extractions. Needless to say it is very likely that many more species remain to be discovered.

30.

PSEUDOPSINAE

This is a small Holarctic subfamily of four genera and about fifty-five species; the majority, about fifty species, are in the genus Pseudopsis Newman, 1834. The remaining genera are Nearctic; Nanobius Herman, 1977 is monotypic while both Zalobius Leconte, 1874 and Asemobius Horn, 1895 contain two species; they are widespread in western mountain areas of the United States. These small species occur in fungi, leaf-litter, decaying vegetation and mammal nests. A single species of Pseudopsis occurs in the U.K. The subfamily is characterized by prominent longitudinal carinae on the pronotum and elytra, and sometimes also the head, and in having a fine stridulatory file on either side of the terminal abdominal sternite. The tarsi are generally five-segmented although in a single species three segmented. In general appearance they resemble some Micropeplinae but are distinguished by the lack of an antennal club.

31.

PAEDERINAE

This very large and cosmopolitan subfamily includes more than 6100 species in about 225 genera and 2 tribes. The Pinophilini Nordman, 1837 includes 26 genera, is mostly tropical and includes some atypical species e.g. some Palaminus Erichson, 1839, which includes about 300 mostly Afrotropical and Neotropical species, are distinctly pubescent, have very large eyes and lack temples, Pinophilus Gravenhorst, 1802, with more than 200 species worldwide except for Europe and Australasia, is more typical of the subfamily but still has the unusual head structure. The New World genus Lathropinus Sharp, 1886, on the other hand, is typical of the subfamily. The huge tribe Paederini Fleming, 1821 includes the majority of the species in about 200 genera and several subtribes. They are mostly medium sized, 2-12mm, elongate, parallel and often flattened (many live under bark); most are drab, from testaceous to brown or black, or with various yellow or red markings, but there are many brightly coloured species and some are metallic. The head is generally proportionally large with rather flat eyes, long temples which curve rather abruptly to a distinct neck, and parallel cheeks. The antennae are filiform and inserted outside the base of the mandibles, often on a raised lateral corner of the frons, the insertions being invisible from above. The pronotum is usually elongate and parallel, often with the anterior and posterior angles oblique, sometimes narrower than the head and usually narrower than the elytra; the prosternum has a large and opaque coxal process and the pro-coxae project above the cavities. Both the meso- and meta-coxae are closely approximated and the meso-coxae are narrow and triangular with the apex projecting posteriorly. The tarsi are five segmented. Although the group is very large it includes some speciose genera which are represented in the U.K. and so our fauna is fairly representative of the tribe, conversely some groups are very unusual e.g. the seven species of the mostly Neotropical genus Myrmecosaurus Wasmann, 1909 have a very unusual head-structure and pronounced raised ridges to the head, pronotum and elytra, quite unlike any European species. The U.K. fauna includes more than 60 species in 16 genera of the Paederini, and the following short list will help to put this into perspective.

 -Tetartopeus Czwalina, 1888 includes 36, mostly Holarctic, species. It is sometimes included as a subgenus of Lathrobium.

 -Lathrobium Gravenhorst, 1802 is a worldwide group of more than 300 species.

 -Lobrathium Mulsant & Rey, 1878 is almost worldwide and includes more than 100 species, many of which are Nearctic.

 -Rugilus Leach, 1819 is a worldwide group of more than 200 species.

 -Medon Stephens, 1833 includes more than 350 species and is cosmopolitan.

 -Sunius Stephens, 1829 includes more than 130 species worldwide.

 -Lithocharis Dejean, 1833 includes more than 100 species worldwide.

 -Scopaeus Erichson, 1839 includes more than 400 species worldwide.

 -Paederus Fabricius, 1775 includes more than 600 species worldwide.

 -Astenus Dejean, 1833 includes more than 450 species worldwide.

Most habitats are quite diverse in species, more especially wetland areas, and sampling in most situations is likely to produce at least some species e.g. damp habitats generally, among logs and wood debris, marginal areas, caves, ant nests, compost and decaying vegetation generally, grassland and agricultural borders.

32.

STAPHYLININAE

Among the largest of the subfamilies with more than 7000 species in 6 or 7 tribes, the group as a whole are ‘typical’ staphs ranging from tiny species to the largest in the family; although the U.K. fauna lack the vivid colouration of some tropical forms e.g. the brilliant metallic Neotropical genus Phanolinus (Sharp) or the cryptic Neotropical Leistotrophus versicolor (Gravenhorst, 1806), they are nonetheless representative of the subfamily as a whole. In general the group is distinguished by the antennae being placed on the upper surface of the head, in front of the eyes and inside the base of the mandibles so that the insertions are clearly visible. The antennae are filiform or thickened towards the apex, sometimes with very transverse segments, but never clubbed, members of the Euaesthetinae have the antennae similarly placed but they terminate in a 2-segmented club. The proportions of the various body parts vary enormously and so any description will be tediously long but more detail will be given in the various accounts of species and groups. The U.K. check list includes about 180 species in 30 genera and 3 tribes; Othiini with 6 species, Xantholinini with about 20, and Staphylinini with 158. The classification is still being developed, especially in tropical areas where genera are regularly re-assigned, but it is thought that the U.K. fauna, at least at the generic level, is stable.

The tribes not represented in the U.K. are much smaller; Arrowinini Sotodounikov & Newton, 2005, Morothiini Assing, 2000 and Platyprosopini Lynch, 1884 are monogeneric while the Diochini Casey, 1906 includes 4 genera. Othiini Thomson, C.G., 1859 includes 3 genera, 2 of which occur in the U.K. and one of which, Othius Stephens, 1829, is large with about 130 species worldwide. The vast majority of the species are therefore in the Staphylinini Latreille, 1802 although sometimes the subtribe Xantholinina, as in the U.K. checklist, is considered as a distinct tribe. Some idea of how the U.K. fauna represents the wider world fauna can be gained from the following numbers.   

-Amblyopinina

  -Heterothops Stephens, 1829 includes more than 140 species.

-Quediina

  -Acylophorus Nordmann, 1837 includes more than 100, mostly old-world tropical, species.

  -Quedius Stephens, 1832 includes more than 800 species in 12 subgenera.

-Staphylinina

  -Ocypus Leach, 1819 includes more than 120 species in 4 subgenera and is native to Eurasia          and Africa.

  -Dinothenarus Thomson, C.G., 1858 includes about 30, mostly Palaearctic, species.

  -Ontholestes Ganglebauer, 1895 includes about 30, mostly Eurasian, species.

  -Platydracus Thomson, C.G., 1858 includes more than 400 species in 6 subgenera and occurs      throughout the Palaearctic, Africa and the New World.

  -Tasgius Stephens, 1829 includes about 45 Palaearctic species, some of which are Nearctic         adventives.

-Philonthina

  -Philonthus Stephens, 1829 is cosmopolitan with about 1250 species.

  -Gabrius Stephens, 1829 includes more than 300 mostly Eurasian and African species.

  -Bisnius Stephens, 1829 includes about 70 Holarctic and African species.

  -Cafius Stephens, 1829 includes about 50 species found on seashores worldwide.

  -Neobisnius Ganglbauer, 1895 includes more than 100 species.

  -Erichsonius Fauvel, 1874 includes more than 140 Holarctic, Oriental and Afrotropical species.

-Xantholinina-genera of this group are generally much less speciose.

  -Leptacinus Erichson, 1839 is cosmopolitan with about 80 species.

  -Nudobius Thomson, C.G., 1860 includes about 45 Eurasian, African and Neotropical species.

  -Gauropterus Thomson, C.G., 1860 includes about 30 species throughout the world with the          exception of Australasia.

  -Gyrohypnus Leach, 1819 includes about 20 Holarctic and Oriental species.

  -Hypnogyra Casey, 1906 includes 12 species and is Holarctic.

All members of the group are thought to be predators or scavengers and they occur in a wide range of habitats, often opportunistically, e.g. dung, carrion, decaying vegetation, mammal nests and marginal environments, some are confined to the seashore and a few live in the nests of social insects. Many will be seen to occur rapidly and in large numbers in carrion or dung traps. They will turn up regularly when sweeping vegetation and turning stones and logs etc. and many are active at night on pathways and tree-trunks, and some will occur in huge numbers at decaying terrestrial fungi and dung.

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