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Ennearthron cornutum (Gyllenhal, 1827)







POLYPHAGA Emery, 1886

TENEBRIONOIDEA Latreille, 1802

CIIDAE Leach, 1819

CIINAE Leach, 1819

CIINI Leach, 1819

Ennearthron Mellié, 1847

Widespread though local and generally scarce throughout Europe, extending south into central Italy and the northern Balkan countries and north into the UK and the far north of Fennoscandia, this species is otherwise known from the entire northern Palaearctic region, including Asia Minor and Japan, and it has recently (2020) been found in Iran. In the UK it occurs locally across England as far north as the Humber and there are a few scattered records further north to the Scottish border, Wales and Ireland. The typical habitats are deciduous woodland and wooded parkland with plenty of older trees in various states of decay, but they may also occur on individual trees in hedgerows and gardens. Adults are present year-round, they overwinter among host fungi, under bark or among debris in hollows etc. and are active from March until November, gradually increasing in abundance during the spring and peaking in June and July. The species is associated with a range of fungi, in the UK often on Fomitopsis betulina (Bull.) Cui, Han & Dai (2016) and Ganoderma applanatum (Pers.) Pat. but more generally on Fomitopsis pinicola (Sw. (1810), Daedalea quercina (L.) Pers. (1801), Daedaleopsis confragosa (Bolton) J.Schröt. (1888), Fomes fomentarius (L.) Fr. 1849, Fomitiporia robusta (P. Karst.) Fiasson & Niemelä, Fuscoporia contigua (Pers.) G. Cunn., Ischnoderma benzoinum (Wahlenb.) P. Karst., Trametes betulinus (L.) Pilát (1939), Laetiporus sulphureus (Bull.) Murrill (1920),  Phaeolus schweinitzii (Fr.) Pat. (1900) and Stereum hirsutum (Willd.) Pers. (1800) and occasionally other species of Trametes Fr. (1836), Inonotus P. Karst. (1879), Phellinus (L.) Quél. (1886), Trichaptum Murrill (1904) and Tyromyces P. Karst. (1881). Thus most fairly rigid sporocarps developing on broadleaf trees might be worth investigating for the species although their presence does not mean that the fungi is a larval host e.g. adults have been found in Phellinus pomaceus (Pers.) Maire, (1933), and this is the only species of Ciidae associated with this fungi in the UK (Whitehead, 1999) but there was no evidence of the beetle breeding. Larvae have been recorded from a range of fungi and it is likely they are more generalist feeders in this respect, they occur in spring and summer and pupation occurs within host tissue to produce new-generation adults in the summer. Winter is probably passed mainly in the adult stage but they remain active, at least among host tissue, in all but the coldest periods and so breeding may, to some extent, also occur in the autumn. Adults may be sampled by searching through or tapping host material over a sheet, they occur in extraction samples throughout the year, and during warm spring and summer spells they occur in flight-interception traps, although they will need to be examined carefully as several species often occur in the same sample.

Enearthron cornutum 1

Enearthron cornutum 1

© Lech Borowiec

Enearthron cornutum 2

Enearthron cornutum 2

© Udo Schmidt

1.6-2.3 mm. Readily distinguished among our fauna by the size and the 9-segmented antennae which terminate in a loose 3-segmented club. Entirely shiny reddish-brown or with the elytra a little darker, dorsal surface with dense short scale-like pubescence, those on the elytra arranged, at least in places, in loose longitudinal rows. Legs pale brown, antennae pale with the clubs darkened. Male head with a broad tooth either side on the anterior margin, female head normal. Pronotum broadest about the middle and narrowed to obtuse angles, surface smooth, moderately densely punctured throughout and as shiny as the elytra. Anterior pronotal margin produced into two teeth in males, normal in females. Elytra elongate (at least 1.5X longer than wide), near parallel-sided from angled shoulders to a continuous apical margin, surface smooth and densely punctured throughout, a little more strongly so than the pronotum. Outer apical margin of front tibiae produced into a sharp tooth. Our only other member of the family with 9-segmented antennae, Sulcasis nitidus (Fabricius, 1792) is consistently smaller, 1.2-1.4 mm and has the pronotum finely shagreened and so it appear distinctly less shiny than the elytra.

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