Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz

Oedemeridae

False Blister-beetles.

General appearance. 5–17 mm long. Body length/maximum body width 2.4–4.9. Elytral length/pronotal length 3.1–7.2. Base of prothorax distinctly narrower than the combined elytral bases. Greatest prothoracic width not narrower or only slightly narrower than the greatest elytral width, or distinctly narrower than greatest elytral width. Body noticeably widest immediately behind the thorax. Beetles elongate; not necked; somewhat waisted to conspicuously waisted; conspicuously long-legged; usually pale yellowish brown, sometimes with darker pattern or spots. Upper surfaces of body non-glabrous; not bristly; with neither scales nor scale-like setae.

Detailed morphology. Beetles prognathous. Inclination of the head slight. Eyes strongly protuberant; without bristles. The labrum at least partly visible in antero-dorsal view; labrum mostly moderately to heavily sclerotized. Mandibles with a well developed mola, or with a reduced mola. The mandibular apices simple, or bidentate or bilobed. The incisor edges of the mandibles simple, or with a single tooth, or with two or more teeth. The maxillae with distinct galea and lacinia apically to the palp. The apical segment of the maxillary palps cylindrical to fusiform, or somewhat expanded and truncate to subtriangular, or securiform to cultriform. The apical segment of the labial palps more or less expanded apically, or not expanded apically. Antennae short to long, but not exceeding the insect’s head to tail length; 11(–12) segmented (long). Antennal scape not swollen. Antennae filiform. Antennal insertions visible from above, or hidden from above.

Cervical sclerites present. Prothorax longer than wide. Pronotal length/maximum pronotal width 0.72–2.2. The pronotum without lateral keels. Prothorax at its widest markedly narrower than the adjoining part of the abdomen. Prothorax without notopleural sutures. Scutellum conspicuous to highly reduced; if applicable, not elevated; anteriorly simple; posteriorly narrowly rounded or acute, or broadly rounded or obtusely angulate, or truncate. The prosternal process present; incomplete; 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; medianly confluent; slightly transverse, or circular to longer than wide; with narrow lateral extensions, or without lateral extensions; internally closed by a slender bar. The mid-leg coxae countersunk in ‘mesocoxal cavities’; separated by less than the shortest diameter of the cavity. The mid-leg coxal cavities contiguous; not or scarcely oblique, or markedly oblique; open laterally. Hind-leg coxae contiguous or narrowly separated; extending laterally to meet the elytra; not shaped posteriorly to receive the femur. Tarsal segmentation formula 5, 5, 4. The tarsi exhibiting bilobed segments (penultimate segments bilobed and spongy beneath); without ‘hidden’ segments (basal segment long). 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, or one-toothed or bifid. Hind tarsi with one segment fewer than the mid-tarsi; 4-segmented.

Elytral length/maximum width across the elytra 1.85–4.3. Elytra individually distinctly tapered to their apices; not meeting along the full length of the mid-line; covering most to all of the abdomen to short, exposing several terminal abdominal tergites, or greatly reduced; exposing at least one but fewer than three complete abdominal tergites (and proximally rounded); not truncate; rather soft; always ribbed; non-glabrous (finely and uniformly pubescent). Elytra apunctate, irregularly punctate, or each with fewer than 6 longitudinal lines of punctures or impressed striae. Scutellary striole absent. Wings well developed, or absent or much reduced. Wings without an anal lobe. Wings with a medial fleck, or without a medial fleck; the medial fleck when present, not bisected by a vein. Abdominal sternites 5–6; comprising both fused and moveable components. Basal abdominal sternites immovably joined 2. Abdominal segment 8 apparently without functional spiracles. The male external genitalia tenebrionoid.

Adult habitat, ecology. Not predacious; on living vegetation, or under bark, or associated with flowers; phytophagous (e.g., pollen feeders).

Larvae. Mature larvae small to medium-sized to relatively large. The larvae elongate and more or less parallel-sided. Body circular in cross-section. Vestiture restricted to fine hairs or setae. The larvae dorsally only very lightly pigmented or sclerotized; ventrally only very lightly pigmented. The antennae 3 segmented. Stemmata present, or absent; on either side of the larval head when present, 2, or 5. The frontoclypeal suture between frons and clypeus indistinct or absent. The labrum and head capsule separated by a complete suture. Apices of the mandibles bilobed or bidentate, or trilobed or tridentate. 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 or annular-multiforous); without spiracular tubes. The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The last abdominal segment without cerci.

Larvae mostly in rotting wood (including driftwood and marine timbers), or in living vegetation; consuming rotting wood, or phytophagous (with some feeding on roots or stems of herbaceous plants).

Classification. Suborder Polyphaga; Infraorder Cucujiformia; Superfamily Tenebrionoidea.

Representation in Britain and Ireland, and worldwide. About 1500 species worldwide; genera about 100. 8 species in Britain; genera in Britain 5; Chrysanthia, Ischnomera, Nacerdes, Oedemera, Oncomera. E.g., Ischnomera sanguinicollis (Red-and-Green Oedemera).

General comments. Slender, parallel-sided beetles, with rather soft integument and fine uniform pubescence; often coastal. The cosmopolitan Nacerdes melanura breeds in warves and old ships’ timbers.

Illustrations. • Ischnomera sanguinicollis (Red-and-green Oedemera: B. Ent. 390). • Ischnomera sanguinicollis (details, B. Ent. 390). • Ischnomera sanguinicollis (B. Ent. 390: legend+text). • Ischnomera sanguinicollis (B. Ent. 390: text, cont.). • Oedemera femorata: photo, Giles Watson. • Ischnomera (2 spp.), Nacerdes melaneura, Oedemera (2 spp.), Oncomera femorata (with Pyrochroidae, Scraptiidae, Mordellidae): Fowler 5, 148 (1891). • Fowler 5, 148 (1891): original legend.. • Oedemera virescens, with unrelated taxa: Fowler Suppl. 19, 1913. • Fowler Suppl. 19, 1913: original legend..


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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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