Rhizophagus ferrugineus (Paykull, 1800)

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POLYPHAGA Emery, 1886

CUCUJOIDEA Latreille, 1802

MONOTOMIDAE Laporte, 1840

RHIZOPHAGINAE Redtenbacher, 1845

Rhizophagus Herbst,1793

This species has a very wide range in Europe, from mountainous regions of Spain to Greece and Ukraine in the south and extending north to the UK and beyond the Arctic Circle in Scandinavia, it is present on most of the Mediterranean and Atlantic islands and in North Africa, and is reported sporadically across much of the northern Palaearctic region. Over much of this area it is locally common in suitable habitats while in the north it occasionally swarms in very large numbers in extensive conifer woodland. In the UK it is locally common across southern England and Wales, and less so further north to the Scottish Highlands and in the north of Ireland. Typical habitats are all types of woodland, wooded parkland and pasture, and the species sometimes occurs on individual broadleaf trees in hedgerows or on roadsides etc. Adults occur year-round; they overwinter under bark or among debris in hollows etc and are active over a long season from March until November, peaking in abundance between May and July. Specimens occasionally occur among litter near old decaying trees but they spend most of their time under bark or among old sporocarps, on which they are thought to feed, emerging at night to roam on the surface, mate and occasionally feed at sap. On the continent the species is usually associated with conifers, and especially spruces (Picea Mill.), usually where they are infested with scolytid larvae, and adults regularly occur at alcohol-baited traps used to attract wood-boring beetles. Little is known of the biology but mating has been observed from late spring until the autumn, and while the species seems to be closely associated with conifer-scolytids on the continent, it seems to occur more widely in the UK, often appearing under dead bark or among debris with no obvious scolytid association, and adults have been recorded from Cossus burrows and in wasps nests. Beyond swarming, which may occur on warm evenings, adults usually occur in small numbers or as single specimens, often alongside larger numbers of more common members of the genus such as R. dispar, they sometimes appear while working bark or among samples of debris taken from hollows during the winter, and may appear in suitably-placed flight-interception traps during the spring and summer.

Rhizophagus ferrugineus 1

Rhizophagus ferrugineus 1

Rhizophagus ferrugineus 2

Rhizophagus ferrugineus 2

© Lech Borowiec

Rhizophagus ferrugineus 3

Rhizophagus ferrugineus 3

© U.Schmidt

3.0-4.6mm. Rather flattened, elongate and parallel-sided, glabrous and entirely brown to reddish-brown. Head transverse and distinctly narrower than the pronotum, with converging cheeks and temples and small and only slightly protruding eyes, surface smoothly convex and moderately strongly punctured throughout. Third antennomere elongate, about as long as 4-6 combined, last two antennomeres distinctly (though narrowly) visible beyond the enlarged ninth segment. Pronotum elongate, broadest in front of the middle and smoothly narrowed to rounded posterior angles and projecting anterior angles, surface weakly convex and evenly punctured throughout; a little more strongly and less densely than on the head, and those towards the lateral margins distinctly elongate. Prosternal process convex. Pygidium strongly punctured, especially towards the apex. Elytra elongate and gently narrowed from angled or weakly-toothed shoulders to separately-rounded apical margins, all striae distinct and strongly punctured to the apex; the outer striae only a little weaker than the inner ones, interstices of more-or-less equal width throughout, the second with only a few scattered small punctures in the basal half. All tibiae expanded from the base to a truncate apex; the front tibiae with three or four short but easily visible external spines, middle tibiae with at least three much stronger spines and the hind tibiae with one or two short spines towards the apex. In males the metasternum bears two rows of long setae and the first visible abdominal sternite is broad and slightly depressed towards the apex.