Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz


~Zopheridae-Colydiinae; currently including Bothrideridae-Teredinae.

Cylindrical Bark Beetles.

General appearance. 1.3–6 mm long. Body length/maximum body width 1.5–4.5. Elytral length/pronotal length 1.5–3.5. Base of prothorax not or scarcely narrower than the combined elytral bases, or 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-oval to elongate; dorsally flattened, or dorsally strongly convex to cylindric; not necked; conspicuously waisted; unpatterned, yellow, brown, or black. Upper surfaces of body glabrous or subglabrous, or non-glabrous; exhibiting stiff, erect, dark bristles, or not bristly; exhibiting scales or scale-like setae, or with neither scales nor scale-like setae.

Detailed morphology. Eyes strongly protuberant, or not strongly protuberant; bristly, or without bristles. 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. The mandibular apices simple, or bidentate or bilobed. The incisor edges of the mandibles simple, or 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 very short to short; (10–)11 segmented. Antennal scape not swollen. Antennae clubbed. Antennal clubs 2 segmented, or 3 segmented (oval or spherical). Antennal insertions hidden from above; not hidden by lateral extensions of the frons (being under the frontal margin).

Cervical sclerites absent. Prothorax longer than wide. Pronotal length/maximum pronotal width 0.4–1.75. The pronotum with lateral keels (pronotal carinae), or without lateral keels; keels when present, complete. Prothorax at its widest markedly narrower than the adjoining part of the abdomen, or not markedly narrower than the adjoining part of the abdomen; having the front corners produced, or with serrated sides (at least sometimes), or with neither produced front corners nor serrated sides (?). Prothorax without notopleural sutures. Scutellum conspicuous to absent; when applicable, elevated above the mesoscutum in lateral view, or not elevated; anteriorly simple; posteriorly broadly rounded or obtusely angulate, or truncate. 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; variously broadly open, or narrowly open, or narrowly closed, or broadly closed; quite widely separated; circular to longer than wide; without lateral extensions; internally open. The mid-leg coxae countersunk in ‘mesocoxal cavities’; separated by less than the shortest diameter of the cavity, or more than the shortest diameter of the cavity. The mid-leg coxal cavities narrowly separated, or moderately to widely separated; not or scarcely oblique; closed laterally. Hind-leg coxae contiguous or narrowly separated, or widely separated; not markedly extended laterally; not shaped posteriorly to receive the femur. Tarsal segmentation formula 4, 4, 4, or 3, 3, 3, or 5, 4, 4 (rarely). The tarsi without bilobed segments; without ‘hidden’ segments. Front tarsi with as many segments as the mid-tarsi; 3-segmented, or 4-segmented. Mid-leg tarsi 3-segmented, or 4-segmented; tetramerous, or trimerous; 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; 3-segmented, or 4-segmented.

Elytral length/maximum width across the elytra 1–3.2. Elytra covering most to all of the abdomen; exposing no more than part of the terminal tergite; dull; rough, or tuberculate, or ribbed. Elytra with six or more longitudinal lines of punctures, or with six or more impressed striae; the lines per elytron 9, or 10. Scutellary striole present, or absent. Wings well developed, or absent or much reduced. Wings with an anal lobe, or 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; all articulated and moveable, or comprising both fused and moveable components, or all fused and immoveable. Basal abdominal sternites immovably joined when present, 3–5. Abdominal segment 8 apparently without functional spiracles. The male external genitalia tenebrionoid.

Adult habitat, ecology. Land-dwellers; predacious (and some ectoparasitic on larvae or pupae of other beetles), or not predacious (mostly); in decaying plant material, in rotting wood, under bark, and associated with fungi; mostly 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 somewhat flattened. Vestiture restricted to fine hairs or setae, or not restricted to fine hairs or setae (Teredinae). The larvae dorsally heavily pigmented or sclerotized, or dorsally only very lightly pigmented or sclerotized; ventrally only very lightly pigmented. The antennae 3 segmented. Stemmata present, or absent (Anommatinae, Pycnomerus); on either side of the larval head when present, 5 (Colydiinae), or 6 (Teredinae). The frontoclypeal suture between frons and clypeus indistinct or absent, or distinct. The labrum and head capsule separated by a complete suture. Apices of the mandibles bilobed or bidentate. 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 extending to the underside. The abdomen having functional spiracles on anterior segments (these annular-biforous); without spiracular tubes. The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The last abdominal segment with cerci, or without cerci.

Larvae predacious, or not predacious (mostly); in decaying plant material, in rotting wood, under bark, and associated with fungi; mostly consuming decaying plant material and mycetophagous.

The larvae subcylindrical, with a 9-segmented abdomen.

Classification. Suborder Polyphaga; Infraorder Cucujiformia; Superfamily Tenebrionoidea.

Representation in Britain and Ireland, and worldwide. Genera about 120 (?). 17 species in Britain; genera in Britain 13; Bitoma, Cicones, Ortrhocerus, etc.; also Oxylaemus and Teredus, which are referred to Bothrideridae in recent treatments. E.g., Bitoma crenata (Saddle-back Bitoma); Cicones variegatus (Hornbeam Cicones); Ortrhocerus clavicornis (Hairy-horned Beetle).

General comments. Dull, cylindrical or flattened beetles, usually dark brown or black, densely punctured or coarsely sculptured and covered with tiny flattened hairs..

Illustrations. • Aglenus, Bitoma, Cicones, Colydium, Endophloeus, Myrmechixenus, Orthocerus, Oxylaemus, Synchita, Teredus (with Erotylidae): Fowler 3, 84 (1889). • Fowler 3, 84 (1889): original legend.. • Bitoma crenata (Saddle-backed Bitoma: B. Ent. 283). • Bitoma crenata (details, B. Ent. 283). • Bitoma crenata: B. Ent. 283, legend+text. • Bitoma crenata: B. Ent. 283, text cont.. • Cicones variegata Curtis (Hornbeam Cicones: B. Ent. 149). • Cicones variegata: original genus and species descriptions (B. Ent. 149, legend+text). • Cicones variegata: B. Ent. 149, text cont.). • Orthocerus clavicornis (Hairy-horned beetle: B. Ent. 314). • Orthocerus clavicornis (details, B. Ent. 314). • Orthocerus clavicornis: B. Ent. 314, legend+text. • Orthocerus clavicornis: B. Ent. 314, text cont.. • Langelandia anophthalma (with Cerylonidae and Histeridae): Fowler 3, 85 (1889). • Fowler 3, 85 (1889): original legend.. • Aulonium trisulcatum, with unrelated taxa: Fowler Suppl. 13, 1913. • Fowler Suppl. 13, 1913: original legend..

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

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.’.