POLYPHAGA Emery, 1886
SCIRTOIDEA Fleming, 1821
EUCINETUS Germar, 1818
E. meridionalis (Laporte, 1836)
3.3-3.7mm
EUCINETIDAE Lacordaire, 1857
Plate-Thigh Beetles
This recent addition to the British fauna remains scarce and very local in a few southern localities, but may be spreading and so should be looked out for.
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Introduction
A small family of 9 genera and about 40 species of which one, Eucinetus meridionalis (Laporte, 1836), has been recorded in the U.K. They have a worldwide distribution, including most of North America and Canada (4 genera and 11 species) with the greatest diversity being seen in the Eurasian species. 8 species are known from Europe. The common name refers to the hind coxae which are greatly expanded to form plates which cover most of the first abdominal ventrite and, when the beetle is ‘rolled up’, the hind femora and tibia as well. These plates extend forward and laterally to meet the elytral epipleura. Adults are generally elliptical in shape, range in size from 0.8 to 4.0mm, and vary from dull yellow to dark brown or black when mature. The elytra completely cover the abdomen and are finely pubescent and punctured. In Eucinetus these punctures are transversely joined to give the surface a cross-strigose appearance. There is at least one impressed stria on the elytra; this may be weak and only visible near to the suture towards the apex. The antennae are 11-segmented and filiform. The front coxae are conical and obviously protruding. The tibiae have an apical fringe of fine spines, the mid- and hind tibiae also have longer spurs. The front tarsi usually have at least some segments lobed beneath. Claws simple, with a fine, bisetose empodium.
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Description
The transverse elytral microsculpture is reminiscent of some Mordellids, Melandryids and Scraptids, and the beetles display vigorous tumbling movements when caught. They jump readily, if rather weakly, and are quick to fly. Eucinetids all have the 5-5-5 tarsal formula which is easily seen as none of the segments are diminutive and this will readily separate them from the above groups.
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Ecology
They live mostly in fungus covered tree bark or detritus where both the larvae and adults consume moulds and the fruiting bodies of larger fungi. They have been recorded from Pine bark, Eucalyptus leaf litter and in dry debris of Opuntia (all European records.) A few tropical species have developed sucking mouthparts with a fused labral tube and styliform mandibles and maxillae.
Eucinetus meridionalis (Laporte, 1836)
Eucinetus meridionalis is widespread in Europe and may have been expanding its range in recent decades. The present distribution includes most of Europe including the Mediterranean islands, Morroco, Algeria and north to south Scandinavia. It was first reported from Malta in 2001. First discovered in the U.K. in September 1968 (Gardiner, 1968) near Lymington, South Hampshire when a specimen was found among damp litter. Further specimens were found during mid October at the same site. There are now (2015) a few records from the southeast; Hampshire, Dorset, East Anglia and Lincolnshire. Typical of the genus, both adults and larvae are fungivores. They may be found under bark, Black Pine is thought to be favoured, and the adults also visit flowers. They have been attracted to light on the continent. Adults overwinter among bark and litter etc.
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3.3-3.7mm. Eliptical and very convex, especially towards the front. Dark brown, when mature, with elytral apex and clypeal margin pale. Before this colouration develops the entire insect is pale, drab yellow or brown. Legs and first three antennal segments pale-when mature. Head with clypeus produced, anterior margin rounded. Strongly contracted behind large and prominent eyes. Antennae 11-segmented and pubescent. Filiform, segment 3 much smaller than segment 2. Pronotun transverse and narrowed anteriorly, at the base continuous with the elytra. Hind margin produced backwards and curved. Scutellum punctured and pubescent. Elytra widest in front of middle and strongly tapered to the apex. Each elytron with 5 impressed striae which are obliterated towards the base, sometimes these are only obvious towards the apex. Puncturation dense and confluent towards the base giving a less shiny appearance compared to the pronotum. Legs long and slender, pubescent throughout. Front tibiae slightly curved, parallel sided and slender. Mid and hind tibiae widened towards apex. Mid tibiae with a fringe of small, black spines at apex and two large spurs; the outer sharp, the inner rounded at apex. Hind tibial apex similarly fringed and with two sharp spurs, the inner longer. Hind coxal plates dilated obliquely forward, reaching the elytra near the level of the middle coxae. When the beetle is ‘rolled-up’ the hind femora and tibia are concealed under the lateral margins of the coxal plates. Entire underside, including the coxal plates, densely punctured and pubescent.