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Mycetaea subterranea (Fabricius, 1801)

Hairy Cellar Beetle






POLYPHAGA Emery, 1886

CUCUJOIDEA Latreille, 1802


MYCETAEINAE Jacquelin du Val, 1857

Mycetaea Stephens, 1829

Native to the Western Palaearctic region, this species has now become widely established in many regions worldwide including e.g. Africa and North America, and it is even established on the Hawaiian Islands and New Zealand, it is locally common throughout Europe except for the far north and extends into Western Russia, it is also present on most of the Mediterranean islands as well as Madeira, the Canaries and Azores. In the UK it is widespread though local across Central and South East England and Wales and very local and sporadic further north to Southern Scotland although given the lifestyle it is very likely to be under-recorded. Both adults and larvae are mycophagous, the species occurs in the wild but is also synanthropic and more likely to be recorded indoors, adults occur year-round and under natural conditions are active through the spring and summer, peaking in abundance during Spring and early summer, but under artificial conditions they are active throughout the year. Adults may be found among decaying vegetation or in tree hollows, especially where they are infested with fungi, and on the continent they occur in hymenopteran nests and rabbit burrows, but indoors they are very eurytopic. In North America they are frequently associated with mouldy grain in granaries and warehouses but also occur among a range of infested stored products, this is also true in the UK but here a more typical habitat is damp and poorly ventilated cellars and basements where they are associated with mouldy plaster and wood as well as stored food products, seeds and fertilizer etc. There is a strong association with the house fungus Serpula lacrymans (Wulfen) P.Karst (1884) and adults are thought to carry spores to initiate infestations and therefore provide host material for the larvae, but it is very likely that they also use other species that thrive under such conditions (there are at least 12 species of fungi and mould that are widespread and common in older houses in the UK.) Although they may occasionally occur in large numbers in commercial premises they are not considered a pest because they do not infest products directly, rather as an indicator that mould is present and that products need to be examined.  Adults are photophobic and will soon vanish when illuminated but they generally occur in large numbers and so are easily spotted, in such cases any obvious fungus should be investigated as under artificial conditions they are continuously-brooded and the larvae are obvious; 2.0-2.5 when fully developed, pale creamy with scale-like setae on the thoracic and abdominal segments which tend to be longer laterally. Larvae develop in the wild among mycelia under bark and have sometimes been found among various Polyporus species fruiting on trees and fence posts etc. Sampling is a matter of luck, searching bark or sweeping nearby vegetation at night is sometimes productive but the best method is to take samples from rot holes or bark etc. for extraction.

Mycetaea subterranea 1

Mycetaea subterranea 1

© U.Schmidt

Mycetaea subterranea 2

Mycetaea subterranea 2

© Lech Borowiec

1.5-1.8 mm.  Body elongate-oval and discontinuous in outline, entirely reddish-brown or with the forebody entirely or in part darker, dorsal surface with long semi-erect pubescence throughout. Head smoothly convex and sparsely punctured between weakly convex but prominent eyes, frontoclypeal suture deeply impressed between the antennal insertions and clypeus smoothly curved anteriorly. Antennae 11-segmented with a gradual but well-defined 3-segmented club. Pronotum transverse, broadest about the middle and smoothly curved to obsolete anterior angles and near-perpendicular posterior angles, apical margin rounded, basal margin widely bisinuate, surface evenly convex between complete longitudinal keels close to the lateral margin, finely and sparsely punctured throughout. Elytra curved and rather strongly narrowed from obtusely angled shoulders to a continuous apical margin, surface finely punctured throughout, about as strongly as the pronotum, these are mostly random but tend to form partial striae, especially near the suture. Legs long and slender, femora unarmed and tibiae with an apical comb of very fine setae but without spurs. Tarsi 4-segmented but appearing 3-segmented as the small third segment is usually obscured by the deeply lobed second segment.

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