| | Insects of Britain and Ireland: Coleoptera-Scarabaeoidea (dung beetles and chafers) |
General appearance. 7–22(–26) mm long. Body length/maximum body width 1.45–2.56. Elytral length/pronotal length 0.45–5.55. 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; exhibiting bright ‘warning colours’, or without ‘warning colouration’. 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 not prognathous. Inclination of the head slight to very strong (the labrum and mouthparts often visible from above). Eyes two, entire; strongly protuberant, or not strongly protuberant; without bristles; finely facetted. Ocelli absent. The labrum concealed beneath the clypeus. Mandibles absent or vestigial (sometimes), or present; when present, 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, or with a single apical structure additional 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; strongly asymmetric; not elbowed; 10 segmented; with the scape much-elongated, or without a much-elongated scape; clubbed. Antennal clubs tightly lamellate (but with the capacity to open fan-like); 3 segmented. Antennal insertions visible from above, or hidden from above; not in fossae.
Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.45–0.95. The pronotum with lateral keels (pronotal carinae); keels complete, or incomplete. Prothorax at its widest not markedly narrower than the adjoining part of the abdomen. Prothorax without notopleural sutures. Scutellum well developed and conspicuous, or highly reduced; elevated above the mesoscutum in lateral view, or not elevated; anteriorly simple; posteriorly narrowly rounded or acute, or broadly rounded or obtusely angulate. The prosternal process present. The prosternal process entire. The prosternal process slightly overlapping the mesoventrite. Metaventrite without a transverse groove. The fore-leg coxae countersunk in ‘procoxal cavities’. The fore-leg coxal cavities closed behind externally; narrowly closed, or broadly closed; medianly confluent, or narrowly separated; narrowly separated to quite widely separated; strongly transverse, or slightly transverse; without lateral extensions; internally open. The front tibiae with two lateral teeth, or with three lateral teeth (only when the beetle is metallic green). 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. Hind-leg coxae extending laterally to meet the elytra. Tarsal segmentation formula 5, 5, 5 (usually), or 3, 3, 3 (sometimes). The tarsi without bilobed segments; without ‘hidden’ segments. Tarsal claws two; equal (without lateral teeth). The front tarsi present and well developed; front tarsi with as many segments as the mid-tarsi; front tarsi 5-segmented (usually), or 3-segmented. Mid-leg tarsi 5-segmented (usually), or 3-segmented; pentamerous (usually), 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; with an empodium between them, or without an associated empodium. The hind tibiae with two apical spurs. Hind tarsi with as many segments as the mid-tarsi; 5-segmented (usually), or 3-segmented.
Elytral length/maximum width across the elytra 0.87–1.72. 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. The pygidium at least partly exposed beyond the long elytra. Elytra glossy, or dull; 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, or 10 (Trichiini). Scutellary striole absent. Elytra with epipleura, or without epipleura. Elytral epipleura when present, falling short of the elytral tips. Wings well developed. Wings without an anal lobe. Wings veined (the radial cell incomplete or absent). Wings without a medial fleck. Abdominal sternites 6; comprising both fused and moveable components, or all fused and immoveable. Basal abdominal sternites immovably joined 5, or 6. Abdominal segment 8 apparently without functional spiracles. The male external genitalia bilobate.
Adult habitat, ecology. On living vegetation; phytophagous (feeding on leaves and nectar).
Larvae. Mature larvae minute (less than 3 mm long) (rarely), or small to medium-sized to relatively large. The larvae elongate and more or less parallel-sided; not C-shaped (i.e., unlike those of most scarabaeids, and thick, with relatively small head and legs). Body circular in cross-section. Vestiture restricted to fine hairs or setae. The larvae dorsally only very lightly pigmented or sclerotized; ventrally only very lightly pigmented. The antennae 4 segmented, or 5 segmented (rarely more?). Stemmata absent (usually), or present; on either side of the larval head when present, 1. 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 4 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; 2 segmented, or 3 segmented, or 5 segmented; with 1 moveable claw. Visible abdominal segments 9, or 10. Tergum 9 of the abdomen entirely dorsal. The abdomen having functional spiracles on anterior segments (these cribriform); without spiracular tubes. The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The last abdominal segment without cerci.
Larvae in living vegetation, or in decaying plant material, or in dung, or in the soil; consuming decaying plant material.
Mostly curved, C-shaped ‘curl-grubs’, with brownish head, three pairs of well-developed legs and mostly 4-segmented antennae; the anus transverse.
Classification. Suborder Polyphaga; Infraorder Scarabaeiformia; Superfamily Scarabaeoidea.
Worldwide and British representation. About 2600 species worldwide. About 8 species in Britain; genera in Britain 3, or 4; Cetonia, Gnorimus, Oxythyrea, Trichius.
General comments. A mainly tropical subfamily, including such spectacular insects as the African Goliath beetle, which reaches 11 cm in length (see the illustrations of this and other exotic forms).
Cetoniid larvae can move horizontally, and instead of using their small legs, those of some species progress on their backs with worm-like movements aided by their dense abdominal bristles.
Illustrations. • Cetonia stictica (Spotted Chafer: B. Ent. 374. Adventive). • Cetonia stictica: B. Ent. 374, legend+text. • Cetonia stictica: B. Ent. 374, text cont.. • Cetonia aurata (Rose Chafer, May-bug: Giles Watson). Cetonia aurata (Rose Chafer, May Bug). St. Mary’s, Isles of Scilly, June 2006. Giles Watson. • Cetonia and Gnorimus, with Hopliinae, Melolonthinae and Rutelinae: Fowler 4, 103 (1890). HOPLIINAE. 1, Hoplia philanthus. MELOLONTHINAE. 2, Omaloplia ruricola. 3, Serica brunnea. 4, Melolontha melolontha, male; 5, Melolontha hippocastani, female. 6, Amphimallon solstitialis. RUTELINAE. 7, Phyllopertha horticola. 8, Anomala dubia (as Euchlora); 9, A. dubia, var. CETONIINAE. 10, Cetonia aurata; 11, Cetonia cuprea. 12, Gnorimus variabilis; 13, Gnorimus nobilis. From Fowler's plate, with the names from the original legend (q.v.) updated. • Fowler 4, 103 (1890): original legend.. • Trichius fasciatus, with Buprestidae, Throscidae, etc.): Fowler 4, 104 (1890). SCARABAEIDAE-CETONIINAE. 1, Trichius fasciatus. BUPRESTIDAE. 2, Anthaxia nitidula. 3, Agrilus biguttatus; 4, Agrilus sinuatus. 5, Agrilus laticornis; 5a, A. laticornis, male antenna. 6, Aphanisticus pusillus. 7, Trachys minuta. 8, Trachys troglodytes. 9, Trachys pumila. THROSCIDAE. 10, Trixagus dermestoides. 11, Trixagus obtusus. EUCNEMIDAE. 12, Eucnemis capucina; 12a, E. capucina, labium. 13, Eucnemis buprestoides. From Fowler's plate, with the names from the original legend (q.v.) updated. • Exotic Cetoniinae: cf. Goliathus cacicus or G. goliatus (as Scarabaeus, Goliath beetle). Nat. Misc. (1789–1813) vol. 18, 781.. • Exotic Cetoniinae: Dicronorrhina micans (as Scarabaeus, Shining beetle). Nat. Misc. (1789–1813) vol. 23, 974.. • Exotic Cetoniinae: Mecynorrhinella torquata (as Scarabaeus, Collared beetle). Nat. Misc. vol. 24, 1030 (1813)..
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2012 onwards. Insects of Britain and Ireland: Coleoptera-Scarabaeoidea (dung beetles and chafers). Version: 27th July 2019. delta-intkey.com’.
