Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz


Including Alexiidae, Cerasommatidiidae, Cerylonidae part, Latridiidae part, Mycetaeidae; excluding Merophysiidae.

Cellar-beetles, Handsome Fungus Beetles.

General appearance. 2.5–6 mm long. Body length/maximum body width 1.1–2.53. Elytral length/pronotal length 1.9–6.2. 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 oval to elongate-oval; dorsally somewhat convex to dorsally strongly convex; not necked; somewhat waisted to conspicuously waisted. Upper surfaces of body glabrous or subglabrous, or non-glabrous; exhibiting stiff, erect, dark bristles, or not bristly; 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; labrum mostly moderately to heavily sclerotized. Mandibles with a well developed 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. The apical segment of the maxillary palps somewhat expanded and truncate to subtriangular. 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; 4 segmented, or (8–)11 segmented. Antennal scape not swollen. Antennae gradually expanding towards the apex to clubbed. Antennal clubs 3 segmented. Antennal insertions visible from above, or hidden from above.

Cervical sclerites present. Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.3–1.1. 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 to highly reduced, or absent; when present, elevated above the mesoscutum in lateral view, or not elevated; anteriorly simple; posteriorly narrowly rounded or acute, or broadly rounded or obtusely angulate, or truncate. The prosternal process complete, or incomplete; falling short of the mesoventrite to 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 (Alexiidae); when applicable broadly open; narrowly separated, or quite widely separated; slightly transverse, or circular to longer than wide; without lateral extensions; internally open (Alexiidae), or internally closed by a slender bar, or broadly closed internally. 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; open laterally, or closed laterally. Hind-leg coxae widely separated; extending laterally to meet the elytra (Alexiidae), or not markedly extended laterally; not shaped posteriorly to receive the femur. Tarsal segmentation formula 4, 4, 4, or 3, 3, 3 (usually 4 4 4 with a minute third segment, cf. Coccinellidae). The tarsi exhibiting bilobed segments; with a tiny penultimate segment hidden by distal lobing of the fourth and fused to the fifth. Front tarsi with as many segments as the mid-tarsi; 4-segmented. Mid-leg tarsi 4-segmented; pseudotrimeous; the penultimate segment not distinctly shorter than the antepenultimate one, or 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; 4-segmented (but the third segment minute, those of cf. the other legs).

Elytral length/maximum width across the elytra 0.9–1.75. Elytra covering most to all of the abdomen; exposing no more than part of the terminal tergite; non-glabrous (sometimes with scattered hairs), or glabrous. Elytra apunctate, irregularly punctate, or each with fewer than 6 longitudinal lines of punctures or impressed striae. Scutellary striole absent. Elytra with epipleura. Elytral epipleura reaching to the tips of the elytra (or almost). Wings well developed, or absent or much reduced; fringed with long hairs on the hind margin, or not fringed. Wings without an anal lobe. Wings with a medial fleck; the medial fleck not bisected by a vein. Abdominal sternites 5–6; all articulated and moveable. Abdominal segment 8 apparently without functional spiracles. The male external genitalia cucujiform.

Adult habitat, ecology. In decaying plant material, in rotting wood, and associated with fungi; mycetophagous (e.g., in toadstools, fungi on trees, and on moulds).

Larvae. Mature larvae minute (less than 3 mm long), or small to medium-sized. The larvae elongate and more or less parallel-sided, or oblong to ovate. Body circular in cross-section, or somewhat flattened, or strongly flattened. Vestiture restricted to fine hairs or setae, or not restricted to fine hairs or setae. 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; on either side of the larval head when present, 1–4. 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 with a single lobe or tooth, or bilobed or bidentate, or trilobed or tridentate, or multilobed or multidentate. The maxillary palps 3 segmented. The labium with a short ligula between the palps, or with a ligula at least as long as the palps. Labial palps present and segmented; 1 segmented (sometimes in Lycoperdina), 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 (usually annular); with anterior and 8th-segmental spiracles borne at the ends of a series of spiracular tubes (Anamorphinae), or without spiracular tubes. The abdominal apex without a respiratory chamber. The last abdominal segment with cerci (e.g., Lycoperdina, Mycetaea), or without cerci.

Larvae in decaying plant material, in rotting wood, and associated with fungi, or in stored plant products (Mycetaea subterranea being a minor pest in granaries and warehouses); mycetophagous (notably found in fungal fruit bodies on trees, or feeding on moulds).

Classification. Suborder Polyphaga; Superfamily Cucujoidea.

Representation in Britain and Ireland, and worldwide. About 1300 species worldwide; genera about 120. 6 species in Britain; genera in Britain 5; Endomychus, Lycoperdina, Mycetaea, Sphaerosoma, Symbiotes. E.g., Endomychus coccineus (Scarlet Endomychus); Lycoperdina bovistae (Puff-ball Beetle); Mycetaea hirta (Hairy Cellar-beetle), Sphaerosoma (Alexiidae).

General comments. Moderate-sized, convex, often prettily patterned beetles.

Illustrations. • Endomychus coccineus (Scarlet Endomychus: B. Ent. 570). • Endomychus coccineus (details, B. Ent. 570). • Endomychus coccineus: B. Ent. 570, legend+text. • Endomychus coccineus: B. Ent. 570, text cont.. • Lycoperdina bovistae (Puff-ball beetle: B. Ent. 355). • Lycoperdina bovistae: B. Ent. 355, legend+text. • Lycoperdina bovistae: B. Ent. 355, text cont.. • Mycetaea hirta (Hairy Cellar-beetle: B. Ent. 502). • Mycetaea hirta: B. Ent. 502, legend+text. • Mycetaea hirta: B. Ent. 502, text cont.. • Endomychus, Lycoperdina, Mycetaea, Symbiotes, Sphaerosoma (with Coccinellidae and Erotylidae): Fowler 3, 83 (1889). • Fowler 3, 83 (1889): 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.’.