|Staphylinidae Rove Beetles|
| 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.
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.
| <1-35mm. Generally elongate with short or medium length
elytra leaving at least part of the abdomen visible, in some species of Omaliinae
this may not be obvious. Sutural stria of elytra usually straight but may be modified and overlap e.g.
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,
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 Aids)
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 covering 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.
|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.