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Sciodrepoides Hatch, 1933







POLYPHAGA Emery, 1886

STAPHYLINOIDEA Latreille, 1802

LEIODIDAE Fleming, 1821

CHOLEVINAE Kirby, 1837

CHOLEVINI Kirby, 1837

S. fumatus (Spence, 1813)

S. watsoni (Spence, 1813)

S. fumatus (Spence, 1813)

-Antennae shorter, segments four elongate, segment five quadrate to elongate.

-Elytra across the base as wide as the pronotal base.

S. watsoni (Spence, 1813)

-Fourth antennal segment quadrate or slightly transverse.

-Fifth antennal segment distinctly transverse.

-Pronotum usually slightly narrower than the base of the elytra.

Sciodrepoides fumatus (Spence, 1815)

This species is locally common throughout much of the Palaearctic region; in Europe it occurs from Spain to Greece and north to the UK and reaching the Arctic Circle in Fennoscandia, to the east it extends sporadically through Asia Minor and Russia to Siberia, North Korea and Japan, it occurs on some of the Mediterranean islands but is absent from North Africa and the Atlantic islands. It is also recorded from North America but these probably refer to the closely similar S. terminans (LeConte, 1850) which was formerly considered to be a subspecies of the present species. In the UK it is locally common across England and Wales though generally scarce in the West Country and the north and there are a few scattered records from the Scottish Highlands, Skye and Northern Ireland. Adults occur year round but are only rarely recorded during the winter; they are active from March or April until November and peak in abundance during June and July. The typical habitat is open woodland and wooded scrub and parkland but they fly well and might be found in other habitats when attracted to suitable host material. All stages occur among decaying plant remains and carrion and adults sometimes occur in the nests of mammals and birds, the main overwintering stage is not known but adults may overwinter in subterranean mammal nests which might explain why they are seldom recorded at this time. Adults may suddenly occur in large numbers at carrion or, later in the year, at decaying fungi, but they often occur in pitfall traps and sometimes at light in a wide range of habitats, and on the continent (Latvia) they have been recorded in scolytid pheromone traps.

Sciodrepoides watsoni 1

Sciodrepoides watsoni 1

Sciodrepoides fumatus 1

Sciodrepoides fumatus 1

Sciodrepoides watsoni 2

Sciodrepoides watsoni 2

Sciodrepoides watsoni 3

Sciodrepoides watsoni 3

3.0-3.5 mm. Recognized by the small size and the form of the pronotum which is not narrowed towards the base, the only confusion might be with S. watsoni (Spence, 1815), see below. Elongate-oval, moderately convex and discontinuous in outline; the base of the pronotum being wider than the base of the elytra, body entirely dark to pale brown, legs pale brown and antennae dark with the base and at least part of the apical segment pale, entire upper surface finely punctured and with fine decumbent pubescence, the punctures may form transverse series in places but there are no regular transverse striae. Head transverse with an abrupt occipital ridge that abuts the apical pronotal margin, surface smoothly convex and without a distinct frontoclypeal suture, eyes weakly convex situated directly in front of the occipital ridge. Antennae long and gradually expanded to the apex; segments 1-4 elongate, 5 quadrate or elongate, 6 transverse, 7, 9 and 10 longer and much larger than the tiny transverse eighth segment. Pronotum transverse, broadest near almost perpendicular posterior angles and curved to a narrow apical margin, basal margin gently sinuate and surface without distinct structure. Mesosternum smooth; without a fine median ridge. Elytra elongate and smoothly convex, broadest about the middle and narrowed to a continuously-rounded apical margin, sutural stria distinct but variable, otherwise without or with only a hint of very fine striae among the punctures, lateral margin very narrowly explanate. Legs long and slender, tibiae with stout apical spurs but without an apical fringe of setae. Tarsi 5-segmented, basal segments of front and middle tarsi expanded in both sexes, segments otherwise simple.

Sciodrepoides watsoni (Spence, 1813)

This is among the most common and widespread of the European leiodids, it is generally common from the northern Mediterranean to the UK and the far north of Fennoscandia and extends east into Asia Minor and Russia, it is also widespread in the east, extending from Mongolia and Siberia to China, Japan and Korea although this may not be continuous with the western Palaearctic distribution, and it was formally listed from Canada (and possibly the United States) but has now been removed through lack of source material. It is common throughout England and Wales, though less so in the West Country, and very local and rare further north to the Scottish Highlands and in Northern Ireland. Adults are likely to occur wherever carrion appears but they show a preference for open habitats such as grassland and heathland, they fly well and may travel considerable distances to find carrion but they also feed on decaying plant and fungal material though not in dung, they are often recorded from mammal and bird nests and they usually occur in numbers. They are active over a long season from February or March and peak in abundance during early summer, breeding occurs in spring and early summer and they often breed together in numbers. Eggs are laid singly or into the ground beneath carrion or among compost etc and larvae emerge after a day or two, they feed directly on the host material although they may also be predaceous, and they develop very quickly; the first instar lasts about a day, the second for about two days and the third, and final instar, lasts about a week. The fully-grown final instar larvae dig into the soil to construct round cell from debris and soil particles in which to pupate, and the pupal stage lasts for about six days. Under good conditions the entire cycle from egg to adult takes about twenty days. New generation adults appear from June, they are active through the summer but it is not known whether they breed before the autumn, they probably overwinter in the ground or among leaf-litter etc as adults have been recorded through the winter on the continent. They sometimes occur in flight-interception traps and they may be swept from grassland but sampling is easiest using baited pitfall traps or carrion; they are very likely to turn up at any carrion but they naturally seem to prefer small mammal and bird carcases, they will usually occur in numbers along with many other beetles and they often come to disturbed sites such as domestic gardens.

2.6-3.4 mm. Elongate-oval, moderately convex and discontinuous in outline, entirely pale to dark brown, usually with the forebody a little darker than the elytra, legs usually paler than the body, antennae dark with three basal segments and the apex of the terminal segment pale. Dorsal surface with dense, fine and backwardly-produced punctures that give the impression of forming transverse series throughout, and with fine pale or golden pubescence throughout. Head transverse, with a well-defined occipital crest, hypognathous, smoothly convex, with convex and protruding eyes, frontoclypeal suture absent or only weakly defined. Maxillary palps slender, the terminal segment narrow and pointed. Antennae inserted laterally in front of the eyes, gradually thickened to a long, 5-segmented club, segments 1-3 elongate, 4-6 short and transverse, the eighth shorter and slightly narrower than the adjacent segments. Pronotum transverse, widest towards the base and narrowed to a rounded apical margin (from above), posterior angles slightly acute, basal margin weakly sinuate and surface evenly convex. Elytra very slightly narrower across the base than the base of the pronotum, with rounded shoulders and evenly curved to separately-rounded apical margins, without striae but with a sutural striae, at least in the apical half. Legs long and slender, all tibiae with two apical spurs. Front tarsi expanded in both sexes. Apical margin of the fifth abdominal sternite with a median circular incision in the female.

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