Staphylinidae | ||||||||||||||||||
Introduction | ||||||||||||||||||
A large family containing more than an quarter of the
British coleoptera. They seem, perhaps understandably, never to have been particularly popular and neither
have they featured usefully in the various guides to beetles that have appeared over the years.
Apart from the most distinctive forms they are difficult, or impossible in many cases, to figure usefully
because there are so many closely similar species and, without an appreciation of the family as a whole and
some very precise guidance, it probably does more harm than good to use such guides for serious
identification. Having said that, colour pictures from general guides (and there are some with excellent anthologies)
can give an idea of the different forms and might also give confidence to an identification made through keys where only
line drawings have been used. It must also be mentioned that, for somebody interested in Coleoptera but approaching
staphs for the first time, they might seem drab and even tedious e.g. having seived an autumn fungi or dung sample
and obtained a few hundred staphs less than 2mm in length, and a good number of them half this length, one needs a certain resolve
in the aspects of dealing them that follow What follows is our humble effort to help make staphs more accesible. In order to partition the family into maneagable groups, subfamilies and sometimes lower divisions are considered individually.There are many distinctive forms which, when they are learned and (mentally) removed from the list, leave the remainder much easier to appreciate. Notwithstanding this it soon becomes obvious that the problems involved with identification are formidable, and the situation is compounded by there being no comprehensive keys available in English. At this stage, i.e. early in ones study of the staphs, it is worthwhile learning enough German to be able to make sense of the works of Freude et al ¹, these books give only line drawings but they are lucid and somehow easy to use, they do not repeat the mistake of Joy's Handbook ² where line drawings are proportional to a species size so that the smallest figures, which might have been most useful, become almost useless without a great deal of experience. Admittedly one needs to be single minded and very determined with the staphs, they are difficult, but every successful identification provides material that can help guide other specimens through the keys. Studying staphs will soon generate a considerable number of identified specimens but in each case they should be taken as far as possible and then labelled and listed for future reference. This will be frustrating but also worthwhile, the secret is to keep on trying to key things out and remain aware of how far your unidentified specimens go, sooner or later things begin to fall into place. This situation is unfortunate because for those interested in or even (as, sadly, with one of our group ³) excited by dealing with microscopic rove beetles the amount of work needed is very considerable. Almost, it seems, by way of compensation the syaphs are not difficult to collect. They are found in most situations at most times of the year and just about any collecting technique will produce them. Samples of almost anything organic (sometimes even seaweed) will probably contain at least some; sweeping, beating, light trapping, ?? netting, pit fall trapping etc. etc. will produce them. It would be far easier to list situations where they are not found. Some idea of the ecology of the group is given under the subfamily and species descriptions. |
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¹ Die Kafer Mitteleuropas, Freude, Harde, Lohse. Vols 4 and 5 ² Practical handbook of British beetles, Joy ³ The author's son, one of our junior members, continually provides copious amounts of specimens which the father is expected to set, mount and identify - Webmaster. |
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General Description | ||||||||||||||||||
<1-35mm. Generally elongate with short or medium length
elytra leaving at least part of the abdomen visible, in some species of Omaliinae and Scaphidiinae
this may not be obvious. Sutural stria of elytra usually straight but may be modified and overlap e.g. Tachyporinae
or Xantholinus spp.. Abdomen eight segmented and usually flexible, variously covered by elytra, terminal
segments may telescope in so care must be taken to appreciate this. Any serious study will necesitate dissection,
the male and female genitalia are often distinctive. Head from broadly transverse to elongate with temples varying
from dilated to contracted to non-existent, sometimes withdrawn into prothorax. Eyes variable but usually entire,
perhaps best developed in Stenus spp., ocelli present in Omaliinae and Proteininae. Antennae
usually 11 segmented, sometimes 9 or 10, and variable from filiform to broadly thickened or clubbed and variously setose.
Their position of insertion provides the basis of a practical guide to subfamilies. Thorax and abdomen are
variable, from cylindrical to arched or flat, variously sculptured and modified e.g. Omalium, Oxytelus
and Bledius. Legs are generally less variable than other characters; mostly long and/or agile, many species
are capable of rapid movement when disturbed e.g. Ontholestes or Creophilus. Despite the lifestyle of many of the
staphs i.e. burrowing in fungi, dung, carrion etc. the fossorial leg structure of, say, Clivina or Aphodius is
rarely developed. Tarsi 3,4 or 5 segmented many combinations, it will be useful or even essential to be able to count these (ID Aida)
but this presents a great obstacle in tiny Aleocharinae species, so much so that both Freude and Joy provide practical
help to this group as well as help based on tarsal formulae. Those without experience will find the ID notes useful. Part of the reason for presenting this site is to show people some of the Coleoptera of our area while providing guidance as to how to make identifications certain. In some groups of staphs this is very difficult and, for this reason, the Aleocharinae are left out of the following discussion ?? subfamilies. Apart from this the sequence follows that of the checklist from the Coleopterists website which represents, we trust, the latest ideas in staph phylogeny. In this list the former families Psephalidae and Scaphidiidae are treated as subfamilies of the Staphylinidae and so are considered here. Aleocharinae, which require a rather more detailed approach, will be considered separately following the subfamily discussions. |
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Omaliinae | ||||||||||||||||||
25 genera, 70 spp. Antennae 11 segmented. Usually thickened
towards apex, inserted OUTSIDE the base of the mandibles and into the sides of the head some distance in
front of the eyes, their insertion often hidden. Head with two ocelli placed between, or very nearly so, the level
of the hind margin of the eyes. These can be difficult to see, especially when the head is sculptured or strongly
rugose in this region, but with a little experience they are soon recognised; they usually appear lighter than the
surrounding cuticle and are dull yellow or pink. By turning the specimen under strong light at X20 they will soon
be appreciated. Of characteristic form with (usually) elytra long compared to thorax or abdomen and often a broad overall appearance so soon recognised in the field. Proteininae can be superficially similar but have either a single ocelli (Metospsia) or lack them completely. Omalines are found in most situations and may be common, sometimes very common or occasionally in swarms (Eusphalerum on umbel flowers) e.g. |
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Late summer dung and autumn fungi samples can provide huge numbers.
They may be found throughout the winter under bark, among moss or leaf litter and occur commonly in extraction samples
from most situations. Beating spring blossom and sweeping generally will produce them, especially in damp situations
where species diversity seems to be wider. They come to light, often in numbers among swarms of Oxytelinae.
Pitfall trapping is productive as can be bagging, especially umbels on hot days. Although some species have a very restricted distribution ¹ many are widespread and common, and with a year round occurence and very wide habitat preference they form a fascinating group to study. Furthermore, with several keys covering the British fauna ² this is a subfamily where the amateur can make many confident identification ³ |
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¹ Phyllodrepa nigra (Gravenhorst) only a few S.English localities. Dropephylla linearis (Zett.) D.heeri (Heer) and Xylostita monilicornis (Gyllenhal) from a few localities in the scottish highlands. ² Tottenham, Staphylinidae section a, RES Handbooks, 1954 Die Kafer Mitteleuropas, Freude, Harde, Lohse. Vols 4 and 5 Practical handbook of British beetles, Joy ³ It must be borne in mind that our fauna is always changing and reference should be made to an up to date checklist i.e. the Coleopterist website, and journal references or continental works obtained. |
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Proteininae | ||||||||||||||||||
3 genera, 11 spp. Reminiscent of small (≤3mm.) Omaliinae; broad
species with long or relatively long elytra. Antennae inserted under front margin of head. Tarsi 5-5-5 in all species. All
members are very distinctive and soon recognised in the field. Metopsia clypeata (Muller) has a single ocellus centrally near the base of the head. Hind angles of pronotum strongly excised and lateral edges straight. Antennae broadened towards apex. Megarthus (5 spp.) unique in pronotal structure; a strong longitudinal central channel combined with deeply excised hind angles will isolate these species. Without ocelli. Proteinus (5 spp.) shining black or dark brown with long elytra. The antennae are clubbed, joint 11 being very large compared with 10. Members of all genera are common in vegetable refuse. Proteinus and Megarthus in fungi, especially in the autumn when Proteinus species may be present in thousands. Large decomposing bracket fungi around the base of trees seem most productive. Both genera are found in bark extractions all year round. Access to a warm compost heap and a seive will provide a good introduction to this subfamily, usually providing members of all three genera. All species can be identified with confidence from Joy, Tottenham, and Freude although an up to date checklist should also be consulted |
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Micropeplinae | ||||||||||||||||||
1.4-2.5mm. A small subfamily of 2 genera and 5 species.
Formerly a single genus, Micropeplus, as Arrhenopepta? tesserula Curtis (the only British member of this genus)
was formerly included. Unmistakeable by virtue of the strongly ridged pronotum, elytra and abdomen. Pseudopsis also has ridged pronotum and alytra
but here the antennae are 11 segmented and gradually thickened while in Micropeplids they are 9 segmented and distinctly clubbed.
Prosternum with furrows for antennal reception. Tarsi 3 segmented. Head structure is dimorphic, being produced anteriorly to a point in the male. They are found among decaying vegetation, especially where ther is heat; compost heaps and piles of rotting grass cuttings, also in damp soil. These sombre coloured insects, black or brown, yellow when immature, can be difficult to spot among sieved samples but under light they move sluggishly and are easily pootered. Two of our species, M. fulvus ? and M. staphylinoides (Marsham) are quoted as common by Tottenham. Again, well served by keys in Tottenham, Joy and Freude so confident identification should be expected. |
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Pselaphinae | ||||||||||||||||||
19 genera, 53 spp. These are very distinctive species of two
general forms; broad e.g. Bryaxis, and the more typically staphylinid linear form e.g. Euplectus. The two species of Claviger are unusual and, for convenience, not included in the subfamily description that follows. They are small, 2-3mm., with tiny eyes and six segmented (four visible) antennae. A large depression (trichome, a licking spot, an adaptation for living with ants) occupies the (apparent) first abdominal tergite. They are found exclusively in ants nests. Antennae 11 segmented, apically thickened and with a distinctive terminal club. Inserted above mandibles, basal segments obvious. Terminal segment of maxillary palpi longer than others, often highly modified. Tarsi 3 segmented. the first often tiny, and with a single claw (in all British species) but in some (Batrisodes, Tychus there is also a stout seta which can be mistaken for a second claw. Upper surface with deep wide fovea, often between eyes, on pronotum, elytra or on sides of metasternum. Many species are pubescent. So far as identification is concerned these can offer formidable problems, e.g. Euplechus spp. and Biblioplechus spp. where careful dissection is necessary and females can only be determined by comparison or association. Among the staphylinidae as a whole, however they are not likely to be confused with any other subfamily and will soon be recognised instantly when sorting through samples. Collecting these is not easy, we have specimens from grass tussocks, moss and bark from a wide variety of habitats but it must be said that they turn up at random, taking samples specifically to find them can be very frustrating. Berlese extraction is probably best, if time consuming, as one needs to be very diligent and patient if working samples under spotlights; the few we have found by this method have remained stationary for a long time. They are associated with bark and rotten wood, moss, leaf litter, plant tussocks (often from riparian areas), manure heaps and hot beds, in general shaded and moist habitats. Euplectus falsus Bed. has been found in bird's nests. Brachygluta spp. are found only in salt marshes. Many species are associated with ants nests and their surroundings, some are strictly myrmecophilous: Claviger spp., Amauronyx, Bythinopsis and Batrisodes spp. Unfortunately many of our species are rare or very local but by searching carefully and patiently one can confidentally expect to find half a dozen or so fairly quickly. They should be looked for year round. Joy's keys must be considered out of date, and while Pearce's (1957) treatment omits 5 species now on the British list, it is a very good introduction to the subfamily. Besuchet's treatment in Vol 5 (updated 1989) of Die Kafer Mitteleuropas is elegant and well worth the effort involved in its use, the line drawings of insects and adaegi are very good (see page 339!). |
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Phloeocharinae | ||||||||||||||||||
In Britain (and Europe) represented by a single species, Phloeocharis
subtilissima Mannerheim. A small but highly distinctive insect found under bark or among moss on trees. It is not a common
species but its widespread occurence means that one must be aware of its appearance when identifying staphs. More of this
in the discussion on staphylinid identification after the subfamily descriptions. 1.5-2mm. Clothed with long shining whitish grey pubescence, cylindrical and somewhat tapering which suggests Tachyporinae but size and pubescence rule these out. Black or brownish with elytra and appendages lighter. Elytra without striae. Tarsi 5-5-5. Pronotum broader than head and abdomen, without depressions. Antennae thickening apically, inserted under sides of head, outside outer margin of mandibles, the base of joint one being hidden. Small size, shining pubescence and general form will isolate this species. |
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Tachyporinae | ||||||||||||||||||
12 genera, 64 spp.. 2-8mm. All species of characteristic appearance;
fusiform, with abdomen narrowed from base to apex although in some species there is a tendency for segments to telescope
together when set. Head without ocelli, sunk into the thorax so that the (small) temples are not visible. Pronotum
covering front femora, mid and hind tibiae usually with setae. Some species are pubescent (Sepedophilus) and at
first glance may be taken for Phloeocharis but they are much larger ≥ 2.4mm. Similarly Cypha spp. (Aleocharinae)
are superficially similar but much smaller (maximum 1.5mm). Tarsi 4 or 5 segmented. Antennae thickened towards apex, never
clubbed (Trichophyinae, Habrocerinae), inserted outside outer margin of mandibles. Careful attention must be paid to the antennal
insertions as there are Aleocharine genera (e.g.Oxypoda) that might be mistaken for Tachyporinae. Many of our common species
are distinctly coloured or patterned which offers the opportunity to become familiar with the subfamily without too much
effort. Collecting staphs with aview to forming a collection and recording local fauna will quickly produce Tachyporus spp. which can usually be identified with confidence from our pictures and descriptions, other distinctive genera (e.g. Conosoma, Tachinus,Lordithon) will soon follow. Members of this subfamily are common year round in a wide variety of habitats and should be available forstudy at will. Sweeping vegetation or beating shrubs and trees will produce Tachyporus spp. (among others), as will bagging flowers. They are found in dung and rotting vegetation, especially the outer warm layers of compost heaps, often in large numbers and usually a wide species diversity. Searching under bark can be productive year round especially where it is covered in moss or invaded by fungi. Looking under debris anywhere is likely to produce them. Winter Berlese extractions from tussocks, moss and bark etc. almost always produce tachyporines, usually Tachyporus, Conosoma or Tachinus. In our experience the most productive souce is large rotting bracket fungi from around the base of trees at ground level; investigating samples from these during autumn 2006 in Cassiobury park produced almost unbelievable numbers of tachyporinae, among many other groups. Joy's keys still remain veru useful and Hodge and Jones) updates these nicely. Hammond's paper (Sepedophilus) clears up many problems. The group is dealt with in Lohse (1964) Vol.4 (updated 1989, Vol 12). |
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Trichophyinae | ||||||||||||||||||
With a single British (and European) species, Trichophya pilicornis
(Gyllenhal). A local insect throughout England and south Scotland, found in moss and decaying vegetation. In
samples under light they move fast and fly readily so care must be taken. 2.5-3mm. Reminiscent of Tachyporinae and some Aleochararies but distinctive owing to their antennal structure; the two basal segments are dilated, beyond this they are very thin, filiform without a hint of distal thickening and each segment is setae apically, the basal segment also setose medially. Inserted in cavities under sides of head in front of eyes, outside base of mandibles. Eyes prominent, head without temples (Habrocerinae) and pronotum widest at or just behind middle (Habrocerinae). These characteristics will isolate Trichophya. Abdomen bordered, with last two segments setose. Black to light brown with pronotum often darker. Thorax and eltra closely punctate and pubescent, appearing dull in life. Legs yellow, tarsi 5-5-5. Antennae yellow or darkened. Head, including eyes, more or less triangular. Distance between palpi a little longer than the length of the first visible segment (Habrocerus). |
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Habrocerinae | ||||||||||||||||||
With a single British and European species, Habrocerus capillaricornis (Gravenhorst).
A local insect throughout England, found among dead leaves and decaying vegetation. A very agile species, sampling
from where its presence is suspected is best done with liquid filled pitfalls or Berlese extraction. 3-3.5mm. With distinctive antennal structure (as TR//); two basal segments dilated, the rest very thin and without a hint of apical thickening, each segment ringed with long setae apically. Inserted under side of head in front of eyes, outside base of mandibles. Head transverse, with distinct temples. Distance between insertion of palpi about three times the length of the first visible segment (Trichophyinae). Pronotum widest at hind angles, with several setae laterally (Trichophyinae). Abdomen bordered, with long setae to sides of each segment. Pitchy to Pitchy yellow or brown, elytra are sometimes darker, immature specimens lighter. Thorax and elytra not punctured, shining. Apex of abdomen and legs yellow. |
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Aleocharinae | ||||||||||||||||||
At this point in the Coleopterist website the Aleocharinae occur
but we have chosen to review this extensive and diverse subfamily after considering everything else. By doing this
we hope to consider the Aleocharines in the light of what has gone before and thus put the group into context. |
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Scaphidiinae | ||||||||||||||||||
3 genera 5 spp. Formerly Scaphidiidae, now incorporated into
Staphylinidae on grounds of larval morphology ¹. Atypical staphs but very distinctive form. Two species are large
, >4.5mm.; Scaphium immaculatum Olivier, a rare species from Kent, found in moss, and Scaphidium quadrimaculatum Olivier,
common and widespread, under bark or logs. Scaphisoma species are small <2.0 mm. and associated with fungi or
wood/bark around fungi dyring the winter. Joy's key usefully covers four of our species, a fifth, the rare Scaphisoma assimile Erichson is covered in Fowler (3:348) and Freude (3;346). General shape characteristic; very convex above and below, glabrous and very shining. Elytra with well developed sutural striae, truncate at apex exposing 1 or 2 abdominal tergites, the last of which is pointed. Antennae with 5 or 6 terminal segments thickened; symetrical and well developed in Scaphidium, elongate and asymetrical in Scaphisoma, joints 2-6 thin and quadrate or elongate. Basal segment in Scaphisoma long and curved like a small scape. Head narrow, antennae inserted in front of prominent eyes, their insertion visible from above. Pronotum broadened to base with strongly sinuate hind margin which covers the scutellum in Scaphisoma spp. Legs long and thin. Tarsi 5-5-5 with well developed, unmodified claws. |
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¹ Kasule, 1966. Subfamilies of larvae of Staphylinidae. Trans. Roy. Ent. Soc. 118:261-283 |
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Piestinae | ||||||||||||||||||
With a single British species, Siagnium quadricorne Kirby. Very
distinctive due to head structure. Locally distributed throughout southern England and the midlands, found under
damp bark especially during winter. Often common where found. 4-5.5mm. Flat and parallel sided, black or brownish black except as below. At first may be confused with Oxytelinae; the antennae inserted under sides of head in front of eyes, filiform with all joints elongate (much longer in male than female). Without ocelli (Omalliinae). Abdominal tergites 2-5 with curved line basally inside the side border (Oxytelus spp.) but the characteristic appearance of this species will soon be appreciated. Head broad, produced outside mandibles, greatly so in male where it appears horned. Mandibles prominent, with at terminal horn in male. With a transverse ridge each side from some distance behind eyes. Eyes small and prominent. Thorax transverse, without impressions and constricted broadly, about as broad as elytra. Glabrous, diffusely punctate with large and small punctures. Elytra with a complete punctate sutural stria, laterally with incomplete rows of punctures and apex finely punctured throughout, reddish or reddish brown, often lighter basally. Abdomen pitchy red with strong side borders, the oblique baso-lateral lines on tergites 2-5 will distinguish this from most of the British Staphylinidae. Antennae and legs red. Tarsi 5 segmented. |
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Oxytelinae | ||||||||||||||||||
15 genera, 95 species. 1.75-9mm. Although generally with shorter
elytra then the Omaliinae there is often, or perhaps usually, a superficial similarity between the
subfamilies because in each case the antennae are inserted under the sides or front of the head, outside the base of the mandibles,
and this feature is obvious so that, with experience,it is usually a question of to which of these two subfamilies a specimen
belongs, all else being quickly ruled out. Oxytelinae never possess ocelli but it must be stressed that in both groups there
are many small species where high magnification, good lighting and lots of experience are needed to appreciate this;
searching for non-existant ocelli or wondering whether they exist among sculpturation is frustrating. Things become
much easier with experience. With the exception of 4 species the Oxytelinae possess 3 segmented tarsi, again in small
specimens these can be incredibly difficult to count, but likewise things get easier with experience. They are rather parallel sided beetles, usually shining black and/or variously dark brown or red, glabrous and often with the head or pronotum sculptured or modified. Pronotum quadrate or transverse. Abdomen with a double lateral edge of upturned sides. Larger species are distinctive and recognisable in the field, smaller ones need to be looked at very carefully. Siagonium has the appearance of this group, especially when one is familiar with the curved lateral lines at the base of the abdominal segments e.g. Anotylus spp., but once familiar this species is obviously distinctive. Following these subfamily discussionswe present an overview of the Staphylinidae as a whole before embarking upon the Aleocharinae and, to facilitate this, it is useful at this stage to consider the four species of Oxytelinae possessing 5-segmented tarsi. 1. Syntomium aeneum Muller. Widespread but local, among moss in damp woodland. 2.5-3mm. Characteristically shaped, strongly punctate and metallic. 2. Deleaster dichrous (Gravenhorst). Widespread but rare, mostly riparian. 7-9mm. Largest member of the Oxytelinae, larger than any Omaliinae and easily distinguished by size, shape and colour. 3. Coprophilus striatulum (Fab.) Easily distinguished by size, colour and the striate elytra. 6-9mm. 4. Manda mandibularis (Gyll.). Southeast England only, rare. 6-8mm. Colour and narrow parallel form with prominent mandibles will make this distinctive. The species with 3 tarsal segments are a large and diverse group with many common species although some e.g. Carpelinus spp. and Bledius spp. present difficulties with identification. Some of the most impressive species are both common and straightforward to identify and so present the beginner with a good introduction to Oxytelinae and to the staphs as a whole e.g.Anotylus spp., Oxytelus spp. and Platystethus spp. Members of these genera, along with a few Carpelinus, will be found commonly throughout the year but dung (anytime) and autumn fungi will produce them in numbers. Riparian pitfall trapping or sweeping is usually productive, and at least some (usually anotylus rugosus Fab. or Oxytelus laquatus (Marsham.) among others) will come to light, sometimes in swarms. Many are rare and some are of very specialised habitats e.g. Teropalpus unicolor (Sharp) a very rare coastal species from s. Devon or Carpelimus schneideri (Gang.) from the burrows of Bledius spp. Members of the genus Bledius (27 spp.) are interseting; of fossorial habitats and frequenting river banks and salt marshes, they are detected by the small mounds of soil they discard. They have spinose pro and meso tibiae and the body is pedunculate, as in fossorial carabids e.g. Clivina, in some the pronotum and/or head is produced into a horn or horns. Many are local in salt marshes and others are local throughout their inland range but a few are quoted as common (Tottenham), B. pallipes (Gr.) or B.subterraneus Er. Most species though, however local, are common where found. The keys in Joy and Tottenham, especially if used together, are useful for the larger species but beyond these Vol. 4 of Freude will be an excellent aid with clear representative line drawings of each genus, many genetalia figures and much information that can be understood with only a basic grasp of german. |
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Oxyporinae | ||||||||||||||||||
Steninae | ||||||||||||||||||
Euaesthetinae | ||||||||||||||||||
Pseudopsinae | ||||||||||||||||||
With a single very distinctive species; Pseudopsis sulcata Newman.
A widespread but very local insect found in vegetable refuse. The pronotum and elytra have strong longitudinal ridges and
so are reminiscent of Micropeplinae but these are easily separated. 2.5-4mm. Antennae 11 segmented and
gradually thickened, inserted on side of head outside the mandibles. Maxillary palpi with last segment elongate and much
narrower than penultimate. Head quadrate with small eyes and prominent mandibles. Pronotum quadrate with sides smoothly
rounded, broadest before base. Abdomen with broadly upturned sides, each segment with an oblique impression from base
towards hind angle. All segments with a short, stout bristle at hind angle. Head black, body dark brown to black, often
lighter laterally. Appendages light brown. Keys out easily in Joy, Tottenham and Freude. |
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Paederinae | ||||||||||||||||||
Staphylininae | ||||||||||||||||||
Discussion |