Rabocerus foveolatus (Ljungh, 1823)

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POLYPHAGA Emery, 1886

TENEBRIONOIDEA Latreille, 1802

SALPINGIDAE Leach, 1815

SALPINGINAE Leach, 1815

Rabocerus Mulsant, 1859

This species is generally very local and rare, it is widespread in central and northern Europe but the distribution is very disjunct, from the Pyrenees to Northern Italy and Hungary but beyond this only from Germany, UK, Poland and the Baltic countries where it reaches into northern provinces of Fennoscandia. The eastern extent of the range is probably parts of northern European Russia. In the UK it seems to have declined during the 20th century; it remains very local and rare in Southern England and Wales and was formerly known from Northern England and Ireland. The species is associated with dead and decaying wood of a wide range of deciduous trees, mostly in old-established and extensive woodland but also in ancient woodland relicts in parkland and pasture. Adults have been recorded throughout the year, mostly in early spring and autumn and only very occasionally at other times. Little is known of the biology but larvae have been found during the summer in Northern Europe and so it is likely that reproduction occurs in early spring. Both adults and larvae are predatory on subcortical insects and their early stages, and larvae have been recorded from the galleries of Dryocoetes alni (George, 1856) and Scolytus ratzeburgii Janson, 1856. Although recorded from a wide range of trees the species may have a preference for older specimens of alder (Alnus Mill.) in various stages of decay; adults hide under bark and among decaying wood and are active on the surface during the evening and at night.  There seem to be no records from sap but specimens have been recorded from both un-baited and alcohol-baited flight-interception traps in closed-canopy beech woodland in the French Pyrenees (Orlu Reserve, 1600-1750 m).

Rabocerus foveolatus 1

Rabocerus foveolatus 1

© Lech Borowiec

2.8-3.8 mm. Body rather depressed throughout; dark brown to black with a strong metallic bronze or greenish reflection, antennae dark with several pale basal segments, legs brown with dark femora. Head transverse and broadest across convex and prominent eyes, temples converging, clypeus emarginate behind lateral antennal insertions and broadly produced anteriorly, vertex smoothly convex and closely punctured. Antennae 11-segmented with segments 7-11 broader and darker. Pronotum transverse, broadest in front of the middle and narrowed to a rounded apical margin and obtuse posterior angles, basal margin gently curved. Pronotal surface closely punctured throughout, about the same as the head, with two well-defined basal impressions and a much smaller impression towards the lateral margins. Elytra slightly dilated from rounded shoulders to a continuous apical margin, widely but shallowly impressed across the basal quarter or third but otherwise evenly convex, punctures random across the base then forming regular striae which become weaker towards the apex. Legs long and slender; all femora unarmed and equal in size, tibiae only slightly broadened from the base and without external teeth or obvious apical spurs. Tarsi 5-5-4, the basal and terminal segment of each elongate, and the third segment bilobed but narrow. Claws smooth and with a weakly developed basal tooth. There are no obvious differences between the sexes.