Insects of Britain and Ireland: the families of Coleoptera
General appearance. 1.7–6 mm long. Body length/maximum body width 1.6–2.15. Elytral length/pronotal length 1.4–1.95. Base of prothorax not or scarcely narrower than the combined elytral bases. Greatest prothoracic width not narrower or only slightly narrower than the greatest elytral width. Beetles oval to elongate-oval (pointed-oval); stoutly dorsally strongly convex and cylindric; not necked; not waisted to somewhat waisted. Upper surfaces of body glabrous or subglabrous; not bristly; with neither scales nor scale-like setae.
Detailed morphology. Eyes not strongly protuberant; without bristles; finely facetted. 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. 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; filiform to clubbed (i.e., to weakly clubbed). Antennal clubs 5 segmented. Antennal segment 8 not smaller than 7 and 9. Antennal insertions visible from above, or hidden from above.
Cervical sclerites present. Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.55–0.85. 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 to highly reduced, or absent; if applicable, not elevated; anteriorly simple; posteriorly broadly rounded or obtusely angulate. The prosternal process complete, or incomplete; falling short of the mesoventrite to 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; broadly open; medianly confluent, or narrowly separated; circular to longer than wide; with narrow lateral extensions, or without lateral extensions; internally open, or internally closed by a slender bar. The mid-leg coxae countersunk in mesocoxal cavities; separated by more than the shortest diameter of the cavity. The mid-leg coxal cavities moderately to widely separated; not or scarcely oblique; closed laterally. Hind-leg coxae contiguous or narrowly separated, or widely separated; not markedly extended laterally. Tarsal segmentation formula 5, 5, 5. The tarsi without bilobed segments; without hidden segments. 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. Hind tarsi with as many segments as the mid-tarsi; 5-segmented.
Elytral length/maximum width across the elytra 0.86–1.28. Elytra meeting along the length of the mid-line; covering most to all of the abdomen to short, exposing several terminal abdominal tergites; exposing no more than part of the terminal tergite to at least one but fewer than three complete abdominal tergites (exposing the conical, pointed abdominal tip, but longer than in Staphylinidae); somewhat truncate (leaving the tip of the pygidium exposed); glossy; glabrous. Elytra with six or more longitudinal lines of punctures, 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. Wings well developed. Wings without an anal lobe. Wings without a medial fleck. Abdominal sternites 6 (first as long as 2–4 together); all articulated and moveable. Abdominal segment 8 with apparently functional spiracles, or apparently without functional spiracles. The male external genitalia staphylinoid.
Adult habitat, ecology. Land-dwellers; not predacious (?); in decaying plant material, in rotting wood, under bark, and associated with fungi; mycetophagous.
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. 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. The antennae 3 segmented. Stemmata present; on either side of the larval head 5, or 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. 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; 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); 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 not predacious; in decaying plant material, in rotting wood, under bark, and associated with fungi; mainly mycetophagous (on fungal spores and mycelia, and on fresh spore tissue of bracket fungi).
The larvae fusiform and pigmented, with 3-segmented antennae.
Classification. Suborder Polyphaga; Infraorder Staphyliniformia; Superfamily Staphilinoidea.
Representation in Britain and Ireland, and worldwide. About 1200 species worldwide. 5 species in Britain; genera in Britain 3; Scaphidium, Scaphisoma, Scaphium. E.g., Scaphidium quadrimaculatum (Orange-spotted Scaphidium).
General comments. The fore coxae with the trochanters hidden.
Illustrations. • Scaphidium quadrimaculatum (B. Ent. 379). • Scaphidium quadrimaculatum (details, B. Ent. 379). • Scaphidium quadrimaculatum: B. Ent. 379, legend+text. • Scaphidium quadrimaculatum: B. Ent. 379, text cont.. • Scaphidium quadrimaculatum and Scaphisoma agaricinum, with Cryptophagidae and Mycetophagidae: Fowler 3, 95 (1889). • Fowler 3, 95 (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. delta-intkey.com’.