Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz


Alleculidae, Cistelidae, Colydiidae part, Cossyphodidae, Lagriidae, Nilionidae, Rhysopaussidae, Tentyriidae.

Churchyard Beetles, Darkling Beetles, Darkness Dwellers, Nocturnal Ground-beetles, Mealworm-beetles.

General appearance. 1.5–25 mm long. Body length/maximum body width 0.9–4.6. Elytral length/pronotal length 1.25–7.4. 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 round to elongate; conspicuously necked to not necked; not waisted to conspicuously waisted; dark, usually dull 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. Beetles without a rostrum; somewhat prognathous, or not prognathous (mostly). Inclination of the head slight to very strong. Eyes strongly protuberant, or not strongly protuberant; bristly, or without bristles. The labrum at least partly visible in antero-dorsal view (mostly), or concealed beneath the clypeus; labrum mostly mostly moderately to heavily sclerotized. Mandibles with a well developed mola (mostly), or with a reduced mola; with well developed prosthecae to without 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 (mostly?), or with a single apical structure additional to the palp. The apical segment of the maxillary palps variously cylindrical to fusiform, or somewhat expanded and truncate to subtriangular, or securiform to cultriform. 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; 3 segmented, or 6–11 segmented. Antennal scape not swollen. Antennae filiform to gradually expanding towards the apex (usually stout, often moniliform), or clubbed. Antennal insertions hidden from above; hidden by lateral extensions of the frons; not in fossae.

Cervical sclerites consistently absent. Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.2–1.5. The pronotum with lateral keels (pronotal carinae), or without lateral keels; keels when present, complete, or incomplete. Prothorax at its widest markedly narrower than the adjoining part of the abdomen to not markedly narrower than the adjoining part of the abdomen; having the front corners produced, or with serrated sides, or with neither produced front corners nor serrated sides. Prothorax without notopleural sutures. Scutellum conspicuous, or conspicuous to highly reduced, or absent; when applicable, 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 present; interrupted, or entire (in some Alleculinae); when not interrupted, 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 (some Alleculinae), or closed behind externally; variously broadly open, or narrowly open, or narrowly closed, or broadly closed; medianly confluent (some Alleculinae), or narrowly separated to quite widely separated; slightly transverse, or circular to longer than wide; with narrow lateral extensions, or without lateral extensions; variously internally open, 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, or markedly oblique; open laterally, or closed laterally. Hind-leg coxae contiguous or narrowly separated, or widely separated; extending laterally to meet the elytra, or not markedly extended laterally; not shaped posteriorly to receive the femur. Tarsal segmentation formula 5, 5, 4. The tarsi usually without bilobed segments; without ‘hidden’ segments. Front tarsi with as many segments as the mid-tarsi; 5-segmented (sometimes with bilobed segments). 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; with an empodium between them (this sometimes with three or more setae), or without an associated empodium. Hind tarsi with one segment fewer than the mid-tarsi; 4-segmented.

Elytral length/maximum width across the elytra 0.73–3.5. Elytra covering most to all of the abdomen; exposing no more than part of the terminal tergite to at least one but fewer than three complete abdominal tergites; not truncate; usually dull; rough, or tuberculate, or ribbed, or smooth; striate, or without striae. 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 12 or more. Scutellary striole present, or absent. Wings well developed, or absent or much reduced (often, with the elytra joined together); when present, 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 5–7; comprising both fused and moveable components. Basal abdominal sternites immovably joined usually 3. Abdominal segment 8 apparently without functional spiracles. The male external genitalia tenebrionoid.

Adult habitat, ecology. Land-dwellers; in decaying plant material and associated with flowers, or in rotting wood, or in dried plant material, or under bark, or associated with fungi, or on shed fur or feathers, or in stored plant products (the latter including a few pests); necrophagous, feeding on dried animal remains, consuming decaying plant material, eating dried plant material or stored plant products, consuming rotting wood, and mycetophagous.

Larvae. Mature larvae minute (less than 3 mm long) to relatively large. 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. The larvae dorsally heavily pigmented or sclerotized, or dorsally only very lightly pigmented or sclerotized; ventrally more or less heavily pigmented, or ventrally only very lightly pigmented. The antennae 2 segmented (Lagriinae), or 3 segmented. Stemmata present, or absent; on either side of the larval head when present, 1–5. The frontoclypeal suture between frons and clypeus 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. 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, or 2 segmented. Mesothoracic legs present and segmented; 5 segmented; with 1 moveable claw. Visible abdominal segments 9, or 10. Tergum 9 of the abdomen entirely dorsal, or extending to the underside. The abdomen having functional spiracles on anterior segments (these annular or annular-multiforous); 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, or predacious and not predacious (including some facultative predators); in divers hanitats, in living vegetation, in decaying plant material, in rotting wood, in dried plant material, under bark, associated with fungi, in shed fur or feathers, and in the soil, or in stored plant products (including ‘mealworms’); variously necrophagous, feeding on dried animal remains, phytophagous, consuming decaying plant material, eating dried plant material or stored plant products, consuming rotting wood, and mycetophagous.

The larvae usually pigmented, subcylindrical and strongly sclerotized, the legs usually short with the first pair someimes longer; somewhat resembling those of Elateridae, but with distinct clypeus and labrum and abdominal segment 9 not conical.

Classification. Suborder Polyphaga; Infraorder Cucujiformia; Superfamily Tenebrionoidea.

Representation in Britain and Ireland, and worldwide. At least 20000 species worldwide (in 9 subfamilies). 44 species in Britain; genera in Britain 30; Alphitobius, Alphitophagus, Blaps, Bolitophagus, Corticeus, Crypticus, Cteniopus, Cylindronotus, Diaperis, Elodona, Gonodera, Gnatocerus, Helops, Isomira, Lagria, Latheticus, Melanimon, Mycetochara, Omophilus, Opatrum, Palorus, Pentaphyllus, Phaleria, Phelan, Platydema, Prionychus, Pseudocistela, Scaphidema, Tenebrio, Tribolium. E.g., Blaps lethifera (Blunt-tailed Blaps); Cylindronotus pallidus (Welch Helops); Corticeus bicolor (Black-and-red Hypophlaeus); Lagria hirta; Melanimon tibialis (Little Opatrum); Tenebrio obscurus (Flour-beetle); Alphitobius laevigatus (Bake-house beetle); Elodona Agricola; Pseudocistela ceramboides; Omophilus rufitarsis.

General comments. Beetles of very diverse form, variously dull brown or black, or (Lagriidae) yellowish brown, dark blue or green and sometimes metallic; the eyes deeply indented, the thorax and/or elytra often sculptured, and the sides of thorax often with distinct lateral margins.

Illustrations. • Alphitobius laevigatus (Bake-house beetle: B. Ent. 363). • Alphitobius laevigatus: B. Ent. 363, legend+text. • Alphitobius laevigatus: B. Ent. 363, text cont.. • Blaps lethifera (Blunt-tailed Blaps: B. Ent. 148). • Blaps lethifera (B. Ent. 148, legend+text). • Blaps lethifera (B. Ent. 148, text cont.). • Corticeus bicolor (Black-and-red Hypophlaeus: B. Ent. 430). • Corticeus bicolor (details, B. Ent. 430). • Corticeus bicolor: B. Ent. 430, legend+text. • Corticeus bicolor: B. Ent. 430, text cont.. • Cylindrinotus pallidus Curtis (Welch Helops: B. Ent. 298). • Cylindrinotus pallidus: B. Ent. 298, legend+text. • Cylindrinotus pallidus: B. Ent. 298, text cont.. • Diaperis boleti (Orange-spotted Diaperis: B. Ent. 358). • Diaperis boleti: B. Ent. 358, legend+text. • Diaperis boleti: B. Ent. 358, text cont.. • Eledona agricola: B. Ent. 586. • Eledona agricola: B. Ent. 586, legend+text. • Eledona agricola: B. Ent. 586, text cont.. • Lagria hirta: B. Ent. 598. • Lagria hirta: B. Ent. 598, legend+text. • Lagria hirta: B. Ent. 598, text cont.. • Melanimon tibialis (Little Opatrum: B. Ent. 319). • Melanimon tibialis (details, B. Ent. 319). • Melanimon tibialis: B. Ent. 319, legend+text. • Melanimon tibialis: B. Ent. 319, text cont.. • Omophlus rufitarsis: B. Ent. 622. • Omophlus rufitarsis: B. Ent. 622, legend+text. • Omophlus rufitarsis: B. Ent. 622, text cont.. • Pseudocistela ceramboides: B. Ent. 594. • Pseudocistela ceramboides: B. Ent. 594, legend+text. • Pseudocistela ceramboides: B. Ent. 594, text cont.. • Tenebrio obscurus (Flour-beetle, Mealworm beetle: B. Ent. 331). • Tenebrio obscurus: B. Ent. 331, legend+text. • Tenebrio obscurus: B. Ent. 331, text cont.. • Alphitophagus, Blaps, Bolitophagus, Crypticus, Diaperis, Melanimon, Phaleria, Platydema, Phylan, Scaphidema: Fowler 5, 143 (1891). • Fowler 5, 143 (1891): original legend.. • Alphitobius, Corticeus, Cylindronotus, Gnatocerus, Helops, Latheticus, Palorus, Tenebrio, Tribolium: Fowler 5, 144 (1891). • Fowler 5, 144 (1891): original legend.. • Cteniopus, Gonodera, Isomira, Lagria, Latheticus Mycetochara, Omophlus, Prionidus, Pseudocistela (with Tetratomidae): Fowler 5, 145 (1891). • Fowler 5, 145 (1891): original legend.. • Corticeus, Cteniopus, Pentaphylus and Prionychus, with Chrysomelidae and Abdera: Fowler Suppl. 18, 1913. • Fowler Suppl. 18, 1913: original legend.. • Elodona agricola, Pseudocistela ceramboides, Omophlus rufitarsis (Janson 141, 145, 146).

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.’.