Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz


Including Laemophloeidae.

Flat Bark Beetles.

General appearance. 1.3–11 mm long. Body length/maximum body width 2.45–3. Elytral length/pronotal length 2.9–4.75. 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. Beetles elongate; dorsally flattened; not necked; conspicuously waisted. Upper surfaces of body glabrous or subglabrous; not bristly; with neither scales nor scale-like setae.

Detailed morphology. Beetles without a rostrum; prognathous. Inclination of the head slight. Eyes strongly protuberant, or not 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 (e.g., Pediacus), or with a reduced mola (e.g., Cucujus); with well developed prosthecae to without prosthecae. The mandibular apices bidentate or bilobed, or multidentate or multilobed (some Laemophloeidae). The incisor edges of the mandibles simple, or with a single tooth, or with two or more teeth (some Laemophloeidae). 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. Antennal scape not swollen. Antennae filiform (or sub-moniliform), or clubbed. Antennal insertions visible from above, or hidden from above.

Cervical sclerites present (mostly), or absent (Laemophloidae). Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.46–0.85. The pronotum with lateral keels (pronotal carinae); keels complete. Prothorax at its widest not markedly narrower than the adjoining part of the abdomen. Prothorax without notopleural sutures. Scutellum conspicuous; elevated above the mesoscutum in lateral view (Laemophloeidae), or not elevated; anteriorly simple; posteriorly broadly rounded or obtusely angulate. The prosternal process complete; slightly overlapping the mesoventrite. Metaventrite without a transverse groove. The fore-leg coxae countersunk in ‘procoxal cavities’. The fore-leg coxal cavities open behind externally, or closed behind externally (some Laemophloeidae); broadly open, or narrowly open to narrowly closed (Laemophloeidae); narrowly separated, or quite widely separated; slightly transverse; with narrow lateral extensions, or without lateral extensions (Laemophloeidae); internally open. The mid-leg coxae countersunk in ‘mesocoxal cavities’; separated by less than the shortest diameter of the cavity (some Laemophloeidae), or more 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 (mostly), or widely separated (some Laemophloeidae); not markedly extended laterally; not shaped posteriorly to receive the femur. Tarsal segmentation formula 5, 5, 5, or 5, 5, 4, or 4, 4, 4. The tarsi without bilobed segments; with a tiny basal segment that is hard to detect, or without ‘hidden’ segments. Front tarsi with as many segments as the mid-tarsi; 4-segmented, or 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. Hind tarsi with as many segments as the mid-tarsi, or with one segment fewer than the mid-tarsi; 4-segmented, or 5-segmented.

Elytral length/maximum width across the elytra 1.95–2.4. Elytra covering most to all of the abdomen; exposing no more than part of the terminal tergite; glabrous. Elytra with six or more impressed striae (Laemophloeidae), 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, 6–7, or 8. Scutellary striole absent. Elytra with epipleura. Elytral epipleura reaching to the tips of the elytra. Wings well developed. Wings with an anal lobe (Pediacus), or without an anal lobe (mostly). Wings without a medial fleck. Abdominal sternites 5; all articulated and moveable. Abdominal segment 8 apparently without functional spiracles. The male external genitalia cucujiform.

Adult habitat, ecology. Land-dwellers; variously predacious (or facultatively so), or not predacious; under bark (commonly), or in stored plant products; some consuming decaying plant material, or mycetophagous.

Larvae. Mature larvae minute (less than 3 mm long), or small to medium-sized. The larvae elongate and more or less parallel-sided. Body strongly flattened, or circular in cross-section to somewhat flattened (Laemophloeidae only). Vestiture restricted to fine hairs or setae. The larvae dorsally heavily pigmented or sclerotized, or dorsally only very lightly pigmented or sclerotized; ventrally more or less heavily pigmented, or ventrally only very lightly pigmented. The antennae 3 segmented. Stemmata present, or absent (some Pediacus spp.); on either side of the larval head when present, 1–6. 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 9 (Laemophloeidae), or 10. Tergum 9 of the abdomen extending to the underside. The abdomen having functional spiracles on anterior segments (these annular or annular-biforous); with anterior and 8th-segmental spiracles borne at the ends of a series of spiracular tubes (Pediacus, Platisus, and some Cucujus spp.), or without spiracular tubes (Laemophloeidae and some Cucujus spp.). The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The last abdominal segment with cerci (Laemophloeidae and some Cucujus spp.), or without cerci.

Larvae predacious (mostly, seemingly), or not predacious; in rotting wood, or in dried plant material, or under bark, or in stored plant products (some Laemophloeidae); some eating dried plant material or stored plant products, or mycetophagous.

The larvae diverse in form.

Classification. Suborder Polyphaga; Superfamily Cucujoidea.

Representation in Britain and Ireland, and worldwide. At least 50 species worldwide (?). 14 species in Britain; genera in Britain 7; Cryptolestes (Laemophloeidae), Dendrophagus (or Silvanidae?), Laemophloeus, Leptophloeus, Notolaemus (Laemophloeidae), Pediacus, Uleiota (or Silvanidae?. E.g., Cryptolestes spartii (Broom Cucujus).

Illustrations. • Cryptolestes spartii (Curtis): Broom Cucujus, B. Ent. 510. • Cryptolestes spartii (details, B. Ent. 510). • Cryptolestes spartii (B. Ent. 510, legend+text). • Cryptolestes spartii (B. Ent. 510, legend+text). • Dendrophagus crenatus, Leptophloeus clematidis, Uleiota planata (with Silvanidae etc.): Fowler 3, 93 (1889). • Fowler 3, 93 (1889): original legend.. • Cryptolestes spartii, Notolaemus unifasciatus and Pediacus depressus, with Lathridiidae: Fowler 3, 92 (1889). • Fowler 3, 92 (1889): 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.’.