Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz

Eucinetidae

~Cryptomeridae.

Plate-thigh Beetles.

General appearance. 3.2–4 mm long. Body length/maximum body width 1.3–1.85. Elytral length/pronotal length 4–5.8. Base of prothorax not or scarcely narrower than the combined elytral bases. Greatest prothoracic width not narrower or only slightly narrower than the greatest elytral width. Beetles oval to elongate-oval; dorsally somewhat convex; conspicuously necked, or not necked; not waisted. Upper surfaces of body non-glabrous; not bristly; with neither scales nor scale-like setae.

Detailed morphology. The head covered by the thorax. Inclination of the head slight to strong. Eyes strongly protuberant, or not strongly protuberant; without bristles; coarsely facetted. The labrum at least partly visible in antero-dorsal view; labrum mostly moderately to heavily sclerotized. Mandibles with a well developed mola; with well developed prosthecae, or without prosthecae. The mandibular apices simple. The incisor edges of the mandibles with a single tooth. The maxillae with distinct galea and lacinia apically to the palp. The apical segment of the maxillary palps cylindrical to fusiform. The apical segment of the labial palps not expanded apically. Antennae short; 11 segmented; filiform. Antennal insertions visible from above, or hidden from above; not in fossae.

Cervical sclerites present. Pronotal length/maximum pronotal width 0.25–0.5. The pronotum with lateral keels (pronotal carinae); keels complete. Prothorax without notopleural sutures. Scutellum conspicuous; not elevated; anteriorly simple; posteriorly narrowly rounded or acute. The prosternal process complete; falling short of the mesoventrite. Metaventrite without a transverse groove. The fore-leg coxae countersunk in ‘procoxal cavities’. The fore-leg coxal cavities open behind externally; broadly open; narrowly separated; strongly transverse; without lateral extensions; internally open. The mid-leg coxae countersunk in ‘mesocoxal cavities’; separated by less than the shortest diameter of the cavity. The mid-leg coxal cavities moderately to widely separated; not or scarcely oblique; open laterally. Hind-leg coxae contiguous or narrowly separated; much enlarged; extending laterally to meet the elytra. Tarsal segmentation formula 5, 5, 5. The tarsi exhibiting bilobed segments (on the front tarsi); without ‘hidden’ segments. Front tarsi with as many segments as the mid-tarsi; 5-segmented. Mid-leg tarsi 5-segmented; pentamerous; the penultimate segment not distinctly shorter than the antepenultimate one. The claws of the mid-leg tarsi not appendaged. The claws of the mid-leg tarsi simple; with an empodium between them (this with no more than two setae). Hind tarsi with as many segments as the mid-tarsi; 5-segmented.

Elytral length/maximum width across the elytra 1.2–1.55. Elytra exposing no more than part of the terminal tergite; non-glabrous. Elytra with six or more longitudinal lines of punctures, or apunctate, irregularly punctate, or each with fewer than 6 longitudinal lines of punctures or impressed striae; the lines per elytron when more than five, 10. Scutellary striole absent. Wings well developed, or absent or much reduced. Wings with an anal lobe. Wings without a medial fleck. Abdominal sternites 5–7; comprising both fused and moveable components. Basal abdominal sternites immovably joined 2. Abdominal segment 8 with apparently functional spiracles. The male external genitalia trilobate.

Adult habitat, ecology. Land-dwellers; consuming decaying plant material, or consuming rotting wood, or mycetophagous (i.e., probably mycetophagous).

Larvae. Mature larvae minute (less than 3 mm long), or small to medium-sized. The larvae elongate and more or less parallel-sided to oblong to ovate. Body circular in cross-section, or somewhat flattened, or strongly flattened. The larvae dorsally only very lightly pigmented or sclerotized; ventrally only very lightly pigmented. The antennae 3 segmented. Stemmata present; on either side of the larval head 5. The frontoclypeal suture between frons and clypeus indistinct or absent. The labrum and head capsule separated by a complete suture, or partly fused, with an incomplete suture. Apices of the mandibles bilobed or bidentate, or multilobed or multidentate. The maxillary palps 3 segmented. The labium with a short ligula between the palps. Labial palps present and segmented; 2 segmented. Mesothoracic legs present and segmented; 5 segmented; with 1 moveable claw. Visible abdominal segments 10. Tergum 9 of the abdomen entirely dorsal. The abdomen having functional spiracles on anterior segments (these annular); without spiracular tubes. The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The last abdominal segment without cerci.

Larvae in decaying plant material, in rotting wood, and under bark; mycetophagous (some feeding on spores of slime moulds, some on basidiomycete hyphae).

Classification. Suborder Polyphaga; Infraorder Elateriformia; Superfamily Eucinetoidea.

Representation in Britain and Ireland, and worldwide. About 40 species worldwide; genera 9. 1 species in Britain (E. meridionalis); genera in Britain 1; Eucinetus.


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Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the families of Coleoptera. Version: 16th May 2016. delta-intkey.com’.

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