Insects of Britain and Ireland: the families of Coleoptera
Clown Beetles, Hister Beetles.
General appearance. 0.8–10 mm long. Body length/maximum body width 1.1–3.6. Elytral length/pronotal length 0.5–2.5. 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. Body noticeably widest at the rear. Beetles oval; dorsally flattened; not necked; not waisted to somewhat waisted. 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. Beetles prognathous. Inclination of the head slight (the mandibles visible in dorsal view). Eyes strongly protuberant, or 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, or with a reduced mola, or without a mola. The mandibular apices simple. 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. 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; more or less conspicuously elbowed; 8–11 segmented; with the scape much-elongated (and curved); clubbed. Antennal clubs 3 segmented (compact, pilose). Antennal insertions visible from above, or hidden from above.
Cervical sclerites present. Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.45–1.8. The pronotum with lateral keels (pronotal carinae), or without lateral keels; keels if present, 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 applicable, elevated above the mesoscutum in lateral view; anteriorly simple; posteriorly narrowly rounded or acute. The prosternal process complete; slightly overlapping 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; narrowly open; quite widely separated; strongly transverse; internally open. 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; open laterally. Hind-leg coxae 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, or with one segment fewer than the mid-tarsi; 4-segmented, or 5-segmented.
Elytral length/maximum width across the elytra 0.5–1.6. Elytra meeting along the length of the mid-line; covering most to all of the abdomen, or short, exposing several terminal abdominal tergites (fairly, revealing 2 or 2–3 tergites); exposing no more than part of the terminal tergite to at least one but fewer than three complete abdominal tergites. The pygidium at least partly exposed beyond the long elytra. Elytra truncate (leaving the pygidium and the last tergite exposed); glossy; striate (but never fully nine- or ten-striate). Elytra 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. Scutellary striole absent. Wings well developed. Wings with an anal lobe. Wings without a medial fleck. Abdominal tergites 7. Abdominal sternites 5; all articulated and moveable. Abdominal segment 8 apparently without functional spiracles. The male external genitalia histeroid.
Adult habitat, ecology. Predacious, or predacious and not predacious (feeding on assorted small arthropods, and especially on insect larvae); in decaying plant material, or in rotting wood, or under bark, or associated with fungi, or associated with dung, or associated with carrion, or on shed fur or feathers.
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. The larvae 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. The frontoclypeal suture between frons and clypeus indistinct or absent. The labrum and head capsule completely fused, with no suture apparent. Apices of the mandibles with a single lobe or tooth. The maxillary palps 4 segmented, or 5 segmented. The labium without ligula between the palps. Labial palps present and segmented; 2 segmented, or 3 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 biforous or bilabiate); 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 predacious and not predacious (feeding on insect larvae, notably Diptera); in decaying plant material, or in rotting wood, or under bark, or associated with fungi, or in dung, or in carrion, or in shed fur or feathers.
Classification. Suborder Polyphaga; Infraorder Staphyliniformia; Superfamily Histeroidea.
Representation in Britain and Ireland, and worldwide. About 3900 species worldwide. 49 species in Britain; genera in Britain 22; Dendrophilus, Hister, Onthophilus, etc. E.g., Dendrophilus pygmaeus; Hister quadrimaculatus (Lunar-spotted Mimic-beetle); Onthophilus punctatus.
Illustrations. • Abraeus, Acritus, Baeckmanniolus, Dendrophilus, Myrmetes, Onthophilus, Plegaderus, Saprinus, Teretrius: Fowler 3, 86 (1889). • Fowler 3, 86 (1889): original legend.. • Hetaerius, Hister, Kissister, Paralister, Paromalus, Peranus (with Langelandia and Cerylonidae): Fowler 3, 85 (1889). • Fowler 3, 85 (1889): original legend.. • Dendrophilus pygmaeus (Sheppardian Hister: B. Ent. 131). • Dendrophilus pygmaeus (B. Ent. 131, legend+text). • Dendrophilus pygmaeus (B. Ent. 131, text cont.). • Hister quadrimaculatus (Lunar-spotted Mimic-beetle: B. Ent. 470). • Hister quadrimaculatus (details, B. Ent. 470). • Hister quadrimaculatus: B. Ent. 470, legend+text. • Hister quadrimaculatus: B. Ent. 470, text cont.. • Onthophilus punctatus (B. Ent. 220). • Onthophilus punctatus: B. Ent. 220, legend+text. • Onthophilus punctatus: B. Ent. 220, text cont.. • Hypocaccus rugifrons, with unrelated taxa: Fowler Suppl. 13, 1913. • Fowler Suppl. 13, 1913: original legend.. • Onthophilus punctatus (Janson 88).
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’.