Reichenbachia juncorum Leach, 1817

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POLYPHAGA Emery, 1886

STAPHYLINOIDEA Latreille, 1802

STAPHYLINIDAE Latreille, 1802

PSELAPHINAE Latreille, 1802

BRACHYGLUTINI Raffray, 1904

Reichenbachia Leach, 1826

Widespread and locally common, this species occurs throughout western and central Europe from Portugal to the Balkan Peninsula and north to the UK and some southern provinces of Fennoscandia, it is absent from the eastern Baltic countries but is recorded from parts of north western Russia, it is also known from north west Africa and this probably represents the southern extent of the distribution. In the UK it is generally common in Wales, including Anglesey, less so and more sporadic in England north to the Wash and generally scarce further north to the far north of Scotland and across Northern Ireland. The species occurs from lowland to low mountain altitudes and the usual habitats are well-vegetated wetland margins, bogs, swamps and permanently damp grassland, usually beside still water and often on reed bed margins where they sometimes occur in numbers. Adults occur year-round; they overwinter among moss and leaf litter or in tussocks, sometimes at some distance from water, and become active early in the spring, they peak in abundance during early summer and remain active until the autumn. Little is known of the biology but, typical of the subfamily, both adults and larvae are probably predaceous on mites and small insects. Sampling adults usually requires sieving or extracting likely samples but they sometimes occur among flood refuse at any time of the year and on hot summer days they climb stems and foliage and so may be swept, although despite the specific name there seems to be no association with rushes (Juncus L.).

1.3-1.6 mm. Elongate and broadly-oval with the head distinctly narrower than the pronotum, upper surface finely and densely punctured and pubescent, teneral specimens are pale brown throughout but developed adults vary from entirely pale to dark brown to dark brown with the elytral disc variably but often substantially reddish-brown to rich chestnut brown, appendages usually a little paler. Head broadest behind prominent, coarsely-faceted eyes, temples widely rounded to a truncate basal margin and cheeks long and converging to a rounded anterior margin, surface smoothly convex but for an arcuate impression beside each eye and a smaller, round impression between the antennal insertions. Maxillary palps a little longer than one-third the antennal length and very distinctive; basal segment long and asymmetrically expanded towards the apex, second segment short and globular, last visible segment elongate and oval. Antennae inserted laterally towards the anterior margin of the frons and separated by about the length of the basal segment which is longer and broader than the second segment, segments 3-7 elongate, 8 quadrate or nearly so, and 9-11 form a gradual and loose club. Pronotum transverse, broadest behind the middle and narrowed to a rounded apical margin and obtuse posterior angles, surface with a large fovea towards each lateral margin and a much smaller one in front of the basal margin. Elytra broadest behind the middle and smoothly broadened from sloping shoulders to obtuse posterior angles, apical margin truncate and bisinuate, each with broadly-impressed sutural stria and a weaker curved stria on the disc, these almost meeting before the basal margin. Elytral base with two, sometimes indistinct, impressions, one near the sutural striae and one near the base of the discal striae but never impressed between. First visible abdominal tergite strongly bordered and with a short, slightly oblique, impressed line either side of the middle at the base. Legs long and slender, with weakly clavate femora and curved middle and hind tibiae, tarsi 3-segmented, the basal segment diminutive, each with a single small claw. Males may be distinguished by the middle tibiae which have a sharp incurved spur at the inner apical angle, in females this is simple.

Reichenbachia juncorum 1

Reichenbachia juncorum 1

Reichenbachia juncorum 2

Reichenbachia juncorum 2

© U.Schmidt www.kaefer-der-welt.de

Reichenbachia juncorum 3

Reichenbachia juncorum 3

© Lech Borowiec http://www.cassidae.uni.wroc.pl/Colpolon/index.htm