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Scydmaenus rufus Müller, P.W.J. & Kunze, 1822 







POLYPHAGA Emery, 1886

STAPHYLINOIDEA Latreille, 1802

STAPHYLINIDAE Latreille, 1802



SCYDMAENUS Latreille, 1802

A very widespread though local and probably under recorded species present throughout Europe from the Mediterranean north to the UK and southern provinces of Fennoscandia, extending east to the west of Russia, Asia Minor, Caucasus, Iran and Syria and also recorded from Algeria. Here it is locally common in southeast England from Dorset to The Wash and very local and rare in the midlands although adults tend to lead a concealed life and are probably under recorded. Adults occur year round and are active from March until September or October in decaying plant material in a range of habitats including woodland and agricultural borders, they also occur under bark and in moss and are sometimes associated with various ants but in general will only be found in numbers among rather dry and undisturbed composted material in gardens or stables etc.  Adults are predatory and display a strong preference for Oribatid (Oppiidae and Scheloribatidae) mites that cannot form defensive body capsules, mites of other families e.g. Urodinychidae, Mycobatidae and trematuridae are also predated but much less frequently, the feeding process mat take up to five hours during which the mite is carefully dismembered and then eaten from the gnathosomal opening. Little is known of the species biology but larvae have been recorded through the summer and are known to be predacious. Adults may be sampled through the summer by sieving the outer dryer layers of compost heaps, especially those formed of grass cuttings and herbaceous material and generating heat, they usually occur in numbers and are active on the sampling tray, through the winter they occasionally occur among extraction samples from a variety of habitats.

Scydmaenus rufus

Scydmaenus rufus

© Lech Borowiec

Among our UK fauna the genus may be recognized by a distinct incision near the tip of the basal antennomere. 1.4mm, body elongate and constricted between the head and pronotum and the pronotum and elytra, entirely pale brown or orange, including all the appendages. Head constricted and produced in front of small eyes that are continuous in outline with long and only weakly convergent temples, posterior angles rounded to a more or less straight basal margin, surface finely and sparsely punctured and with long pale pubescence. Antennae inserted on the anterior margin in front of the eyes and between the outer margin of the mandibles, the insertions separated by less than the length of the basal segment which is broad and long with a subapical notch, segments 2-5 elongate, segments 6-8 quadrate to transverse and 9-11 enlarged, forming a long and gradual club. Maxillary palps long and well-developed, with an enlarged elongate-oval terminal segment. Pronotum quadrate or nearly so, broadest in front of the middle and narrowed to curved apical and basal margins, anterior angles rounded and indistinct, posterior angles weakly obtuse, surface evenly convex, sparsely and very finely punctured and pubescent, the area before the basal margin is indistinctly wrinkled but without depressions or fovea. Elytra oval and evenly convex, each with a distinct humeral tubercle, with sloping shoulders and continuously rounded apical margin which leaves the pygidium exposed, without striae, punctation sparse and a little stronger than that on the pronotum, pubescence long and pale. All femora gradually thickened towards the apex, tibiae slender and only weakly broadened to the apex, tarsi short and narrow, without lobed segments. Sexual dimorphism is very slight but males may (often) be recognized by their slightly broader front tarsi

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