Sepedophilus marshami (Stephens, 1832)

This is Conosoma pubescens Gr. in Joy's handbook, only six species are included in Joy's key (as Conosoma) whereas there are now nine on the latest (Duff, 2008) checklist. Joy's keys will place our species into the correct genus but a later key by Hammond (1973), which includes all our species as well as notes on distribution, ecology and synonomy, which is not straightforward eg the name pubescens occurs four times on the checklist, should be used for specific determination.

Although undoubtedly widespread the modern distribution of this species is not easy to appreciate eg as pointed out by Hammond (ibid) most old records for pubescens Gr. and testaceus Fab. refer to Marshami (St.) There are many modern records from the midlands, the southeast and scattered through Wales, beyond these there are single records from the west country, Yorkshire, The Isle of Man and an isolated one from the northeast Scottish highlands (NBN). This gives some idea of the modern distribution but with so few records for such an apparently common species the map is likely to be far from complete; Hammond stated that the 'species is widely distributed and probably the most frequently taken of the genus in the British Isles' while Joy gives simply 'common' without any regional qualification.

This very distinctive rove beetle occurs throughout our Watford area in a wide range of situations and at all times of the year. Adults generally occur in pairs although they may sometimes be gregarious eg we found them in numbers among thousands of other staphs in large, rotten and very ammoniacal fruiting bodies of terrestrial bracket fungi on the borders of Whippendell wood during the autumn of 2006 and 2007. Through the winter the most frequent (or obvious) habitat is under shaded logs that have been in contact with the ground for some time so that there is no vegetation, in most cases the beetles are among or near fungal hyphae or fruiting bodies. They also occur, although not very often, among samples extracted from grass tussocks and leaf litter. Between 2005 and 2007 we recorded them from under fallen Oak, Beech and, most frequently, Birch in Cassiobury park; from Horse Chestnut and Bird Cherry in Oxhey park and from under the bark of Willow logs in Radlett road. During the spring and summer they occur in a wider range of habitats; we have sieved them from compost heaps in town centre gardens and from leaf litter throughout Whippendell woods, they are common in piles of decaying grass cuttings on West Herts golf course and among fungi or under loose bark and among debris on logs and stumps in parkland and gardens generally.

This species will soon become familiar in the field, the very elongate 'fusiform' shape (which usually contracts in set specimens), contrasting head, pronotum and elytral colouration and overall silky appearance produced by the pubescence is distinctive.

4-5.5mm (Joy) but this varies widely depending on the degree of contraction of the abdomen; we have a specimen just over 6.5mm in length. Head shiny black, paler anteriorly; labrum and mouthparts testaceous. Finely punctate and pubescent; pubescence mostly directed outward from vertex. Eyes weakly convex, continuous with outline of head and reniform in side view. Antennae testaceous with middle segments darker, long and slender, inserted on side margin of head in front of eyes. Segments 1-4 elongate, 5 and 6 less so, 7 and 8 only slightly so and 9 and 10 more or less quadrate, terminal segment asymetric. Pronotum convex and distinctly wider than elytra, widest behind middle and evenly rounded to obtuse hind angles. Shiny black with margins and hind angles lighter, finely punctate with short and dense, backwardly directed recumbent pubescence. Surface with very fine transverse microsculpture which is just visible at X40. Hind margin evenly curved, not sinuate before hind angles. Elytra quadrate or slightly transverse, sides almost straight and contracted to hind angles, sides without outstanding bristles. Surface finely and densely punctate and pubescent, as pronotum. Ground colour distinctive chestnut brown with dark triangular marks (sometimes vague) at base by suture and shoulders. Abdomen long and strongly tapering although this usually contracts after death, side borders weakly developed and only present on basal segments. Black with apical area of segments lighter. Finely and densely punctate and pubescent, terminal segments with long, dark setae. Legs long and slender, entirely testaceous. Tarsi 5-5-5. Segments 1-3 of protarsi dilated, much more so in the male, fourth segment small, fifth long and slender. Claws smooth and only weakly curved.

The above description will identify typically coloured ie mature specimens, teneral specimens are pale and the elytra do not contrast with the forebody, here the genitalia will need to be compared with the figures of S.constans, S.lusitanicus and S.marshami given in Hammonds paper

Description from 4 Watford specimens at X20

Reference
Hammond, P.M. 1973. Notes on British Staphylinidae 3. The British species of Sepedophilus Gistel Ent.Mon.Mag. 108:130-165.




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