Phalacrus fimetarius (Fabricius, 1787) (=brisouti) Rye, 1872
Appears to be a somewhat local species of southern England (although this is probably not a 'popular' group and so may be under recorded); Thompson includes records from Devon to Kent and north to Northampton and Suffolk while the NBN map (March 2009) includes modern (post 1990) records north to Worcester, Leicester and Lincoln. We have recorded adults from several Watford locations; from Ox-eye daisy (Chrysanthemum leucanthenum) flowers in bright sunshine during June 2006 at Radlett road and swept from flowering sedges beside drainage ditches below Cassiobury park during June and July 2008. Typical habitat is on flowering grasses; Thomson quotes Brachypodium pinnatum (Chalk False-brome), a locally common species on chalk and limestone which flowers between June and August. The larvae develop among flower spikes attacked by smut fungi (Ustileginales) (Hurka).

These small, shiny black and very convex species are soon recognised to generic level in the field but will need to be carefully examined under the microscope for specific determination.

2-3.5 mm (Thompson) Entirely shiny black, oval, convex above and flat below, continuous in outline. head finely punctured, parallel behind eyes and converging anteriorly to smoothly rounded clypeal margin. Eyes at lateral angle and continuous with outline. Mandibles trifid. Last segment of maxillary palps cylindrical. Antennae mounted under side margin of head in front of weakly sinuate anterior margin of eyes, appearing 10 segmented; the basal segment within a pit (view laterally from in front); segments 1 and 2 large, 3-5 elongate, 6-8 quadrate or nearly so and apical segments characteristic; elongate and weakly angled on inner side. Lateral margins of pronotum evenly curved and strongly bordered, basal margin weakly sinuate and very finely bordered (view at X60 in front of scutellum). Surface punctured a little finer than that on head. Microsculpture not obvious at X60 scutellum broadly triangular, punctured as pronotum and with very fine but distinct (X60) microsculpture. Elytral puncturation random as well as tending to form longitudinal lines on disc, these lines become more regular laterally. Surface finely microsculptured, in our specimens best seen at base at X90. Legs black, short and robust. Tibiae broadened towards apex, especially middle pair. This species is most easily recognised by examining the fine spurs on the outside edge of the front tibiae; these are present from the basal third and become denser and a little larger towards the apex so that around the apical curve there is a 'comb' of a dozen or more, these must be viewed obliquely as they curve downward and so may not be immediately obvious from above. Third tarsal segment bilobed, fourth tiny and fifth elongate claws smooth, appendiculate and strongly curved at base.

Identifying P.fimetarius
Five species of Phalacrus are included on our British list (Duff, 2008) and are all keyed by Thompson (1958) who gives splendid line drawings of the antennae (P.fimetarius being very distinctive) and ovipositors (which need to be carefully slide mounted) of each. In this work use is made of the number and arrangement of spines on the outer edge of the protibiae; in the case of fimetarius (and more especially so in combination with the form of the antennae) this character renders identification straightforward at X60.
All species are keyed by Vogt (1967) (who uses the name brisouti Rye - from the form of the antennae this is our fimetarius (Fab.)) who also includes line drawings of the aedeagi.

Joy's key includes four species which are keyed (among other things) on subtle differences in outline. It is difficult to use with any confidence and introduces nomenclature difficulties eg his fimetarius is now accepted as P.coriscus Panz. This key is best ignored.

Description from 3 Watford specimens at X40

Vogt, H. 1967 In Freude, H et al. Die Kafer Das Mitteleuropas 7 158-166