Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz

Cerylonidae

~Cerylidae; = Cerylidae; including Bothrideridae-Anommatinae, Aculagnathidae, Dolosidae, Euxestidae, Murmidiidae. Excluding Bothrideridae-Teredinae.

Minute Bark Beetles.

General appearance. 1.3–2.5 mm long. Body length/maximum body width 1.25–2.8. Elytral length/pronotal length 1.5–4. 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; not necked; somewhat waisted; dark reddish- or yellowish-brown. Upper surfaces of body glabrous or subglabrous, or non-glabrous; 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; coarsely facetted. The labrum at least partly visible in antero-dorsal view, or concealed beneath the clypeus; labrum where recorded, mostly moderately to heavily sclerotized. Mandibles with a well developed mola, or with a reduced mola, or without a mola. The mandibular apices simple, or bidentate or bilobed, or multidentate or multilobed. 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, or with a single apical structure additional to the palp (Bothrideridae-Anommatinae); with stylet-like lobes, or without stylet-like lobes. The apical segment of the maxillary palps cylindrical to fusiform (Murmidiinae, Euxestinae), or aciculate (Ceryloninae). The apical segment of the labial palps not expanded apically. Antennae short; 6–11 segmented. Antennal scape swollen. Antennae clubbed. Antennal clubs not lamellate; 1 segmented, or 3 segmented (spherical, with two small basal segments and a large terminal one); spherical, comprising two small basal segments and a large terminal one. Antennal insertions visible from above.

Cervical sclerites variously present, or absent (consistently absent in Murmidiinae). Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.35–1.1. 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, or highly reduced, or absent; when applicable, elevated above the mesoscutum in lateral view; anteriorly when present, simple; posteriorly narrowly rounded or acute, or broadly rounded or obtusely angulate. The prosternal process complete; falling short of the mesoventrite to slightly overlapping the mesoventrite, or moderately or strongly 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; broadly open, or narrowly open, or narrowly closed, or broadly closed; narrowly separated, or quite widely separated; circular to longer than wide; without lateral extensions; internally open, or internally closed by a slender bar (some Murmidiinae). 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 widely separated; widely separated, not markedly extended laterally; not shaped posteriorly to receive the femur. Tarsal segmentation formula 4, 4, 4, or 3, 3, 3. 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 0.9–1.92. Elytra exposing no more than part of the terminal tergite; glossy; smooth; punctate- striate. Elytra with six or more longitudinal lines of punctures, or with six or more impressed striae, 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 to 10. Scutellary striole absent. Wings well developed, or absent or much reduced; fringed with long hairs on the hind margin, or not fringed. 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. Abdominal segment 8 apparently without functional spiracles. The male external genitalia cucujiform.

Adult habitat, ecology. Land-dwellers; in decaying plant material, in rotting wood, and under bark; usually saprophagous, consuming decaying plant material, or consuming rotting wood, or mycetophagous.

Larvae. Mature larvae minute (less than 3 mm long). The larvae strongly flattened and disc-like (Murmidiinae), or neither strongly flattened nor disc-like; elongate and more or less parallel-sided (mostly), or oblong to ovate. Body somewhat flattened (mostly), or strongly flattened (Murmidiinae). Vestiture restricted to fine hairs or setae (Cerylon, some Euxestinae), or not restricted to fine hairs or setae. The larvae dorsally heavily pigmented or sclerotized (many Ceryloninae), or dorsally only very lightly pigmented or sclerotized; ventrally only very lightly pigmented. The antennae 3 segmented. Stemmata present, or absent (mostly); on either side of the larval head when present, 1–2 (some Euxestinae). The frontoclypeal suture between frons and clypeus indistinct or absent. The labrum and head capsule separated by a complete suture (mostly), or completely fused, with no suture apparent (Cerylon). Apices of the mandibles with a single lobe or tooth, or bilobed or bidentate (Euxestinae), or trilobed or tridentate (Murmidiinae). The maxillary palps 3 segmented. The labium without ligula between the palps, or with a short ligula between the palps. Labial palps present and segmented; 1 segmented (Cerylon), or 2 segmented (usually). 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 (mostly annular, sometimes annular biforous); without spiracular tubes, or with anterior and 8th-segmental spiracles borne at the ends of a series of spiracular tubes (some Euxestinae only). The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The last abdominal segment without cerci.

Larvae probably not predacious (in view of the small hypognathous head); in decaying plant material, in rotting wood, under bark, and in the soil, or in stored plant products (e.g., Murmidius ovalis, in granaries and warehouses); consuming decaying plant material and mycetophagous, or eating dried plant material or stored plant products.

Classification. Suborder Polyphaga; Superfamily Cucujoidea.

Representation in Britain and Ireland, and worldwide. About 450 species worldwide; genera about 50 (mostly tropical/subtropical). 6 species in Britain; genera in Britain 3; Anommatus (Bothrideridae), Cerylon, Murmidius.

General comments. Tiny, smooth, shiny, hairless beetles, only lightly punctured..

Illustrations. • Cerylon fagi, C. ferrugineum, C. histeroides and Murmidius ovalis (with Langelandia and Histeridae): Fowler 3, 85 (1889). • Fowler 3, 85 (1889): original legend.. • Anommatus duodecimstriatus (with Rhizophagidae, Trogossitidae, etc.): Fowler 3, 91 (1889). • Fowler 3, 91 (1889): original legend.. • Cerylon fagi.


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. delta-intkey.com’.

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