Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz




General appearance. 10–15 mm long (?). Body length/maximum body width 1.7–4.25. Elytral length/pronotal length 2.1–3.6. 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 conspicuously necked, or not necked. 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. Beetles prognathous. Inclination of the head slight. Eyes 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; without prosthecae. The mandibular apices simple. The incisor edges of the mandibles 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, or somewhat expanded and truncate to subtriangular. The apical segment of the labial palps more or less expanded apically, or not expanded apically. Antennae about half the insect's head to tail length; 11 segmented; filiform. Antennal insertions visible from above to hidden from above; not hidden by lateral extensions of the frons (inserted between eyes and mandibles, under a frontal ridge).

Cervical sclerites absent. Pronotal length/maximum pronotal width 0.72–2.25. The pronotum with lateral keels (pronotal carinae), or without lateral keels; keels when present, complete, or incomplete. Prothorax with notopleural sutures. Scutellum conspicuous to absent; when applicable, not elevated; anteriorly simple; posteriorly narrowly rounded or acute, or broadly rounded or obtusely angulate. The prosternal process complete; slightly overlapping the mesoventrite. Metaventrite with a transverse groove, or without a transverse groove. The fore-leg coxae countersunk in ‘procoxal cavities’. The fore-leg coxal cavities closed behind externally; narrowly closed to broadly closed; narrowly separated to quite widely separated; circular to longer than wide; without lateral extensions; internally closed by a slender bar. 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 (mostly), or closed laterally (some Eumolpinae). Hind-leg coxae contiguous or narrowly separated; not markedly extended laterally; immoveably fixed to the metasternum and dividing the first abdominal sternite. 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, 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; 5-segmented.

Elytral length/maximum width across the elytra 1.2–3.1. Elytra covering most to all of the abdomen; exposing no more than part of the terminal tergite; without striae. Elytra apunctate, irregularly punctate, or each with fewer than 6 longitudinal lines of punctures or impressed striae. Scutellary striole absent. Wings well developed, or absent or much reduced. Wings without an anal lobe. Wings without a medial fleck. Abdominal sternites 6, or 7; comprising both fused and moveable components. Basal abdominal sternites immovably joined 3. Abdominal segment 8 with apparently functional spiracles. The male external genitalia adephagan.

Adult habitat, ecology. Land-dwellers; predacious (active, fast flying and running ground predators); hunting in the open.

Larvae. Mature larvae small to medium-sized. The larvae elongate and more or less parallel-sided. 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. Stemmata present; on either side of the larval head 4, or 6. 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. The labium with a short ligula between the palps. Labial palps present and segmented; 2 segmented. Mesothoracic legs present and segmented; 6 segmented; with 2 moveable claws. 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 without cerci.

Larvae predacious; living in vertical burrows in the ground and ambushing prey.

Classification. Suborder Polyphaga.

Representation in Britain and Ireland, and worldwide. About 2600 species worldwide. 6 species in Britain; genera in Britain 1; Cicindela. E.g., Cicindela hybrida (Tiger Beetle).

Illustrations. • Cicindela hybrida (Tiger-beetle: B. Ent. 001). • Cicindela hybrida (details, B. Ent. 001). • Cicindela hybrida: B. Ent. 001, legend+text. • Cicindela hybrida: B. Ent. 001, text cont. (2). • Cicindela hybrida: B. Ent. 001, text cont. (3). • Cicindela hybrida: B. Ent. 001, text cont. (4). • Cicindela campestris (Tiger-beetle: photo). • Cicindela campestris (Tiger-beetle, head detail: Giles Watson).

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.’.