Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz


Including Drilidae part, Lycidae part.

Glow-worms, Fireflies.

General appearance. 5–16 mm long. Body length/maximum body width 1.7–5.65. Elytral length/pronotal length 0.68–6.9. 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 elongate to slender; not necked; not waisted to somewhat waisted; luminescent from distal abdominal sternites (female Lampyris and both sexes of Phosphaenus), or not luminescent (male Lampyris). Upper surfaces of body non-glabrous; not bristly; with neither scales nor scale-like setae.

Detailed morphology. Beetles not prognathous. The head covered by the thorax. Inclination of the head strong to very strong. Eyes strongly protuberant, or not strongly protuberant; without bristles; finely facetted. The labrum at least partly visible in antero-dorsal view, or concealed beneath the clypeus; labrum if recordable, mostly moderately to heavily sclerotized. Mandibles present, or absent or vestigial; when present, without a mola. The mandibular apices simple. 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, or somewhat expanded and truncate to subtriangular, or securiform to cultriform. Antennae very short to about half the insect's head to tail length; 6 segmented, or 8–15 segmented, or 20–40 segmented. Antennal scape not swollen. Antennae filiform. Antennal insertions visible from above; not in fossae.

Cervical sclerites present. Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.42–0.97. The pronotum with lateral keels (pronotal carinae); keels complete. Prothorax without notopleural sutures. Scutellum conspicuous (in the males), or conspicuous to absent (in females); when applicable, not elevated; anteriorly simple; posteriorly narrowly rounded or acute, or broadly rounded or obtusely angulate, or truncate, or emarginate. The prosternal process absent. Metaventrite without a transverse groove. The fore-leg coxae countersunk in ‘procoxal cavities’ (in Lampyris males), or attached externally, in the absence of procoxal cavities (in both sexes of Phosphaenus, and the females of Lampyris). The fore-leg coxal cavities in Lampyris males, open behind externally; broadly open; when present, medianly confluent; strongly transverse; without lateral extensions; internally open. The mid-leg coxae countersunk in ‘mesocoxal cavities’, or attached externally, in the absence of mesocoxal cavities; separated by when countersunk, less than the shortest diameter of the cavity. The mid-leg coxal cavities contiguous, or narrowly separated; markedly oblique; when present open laterally. Hind-leg coxae contiguous or narrowly separated, or widely separated (anelytrous females); extending laterally to meet the elytra. Tarsal segmentation formula 5, 5, 5. The tarsi exhibiting 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, or one-toothed or bifid; without an associated empodium. Hind tarsi with as many segments as the mid-tarsi; 5-segmented.

Elytra present (males), or absent (females). Elytral length/maximum width across the elytra 0.38–2.9. Elytra individually distinctly tapered to their apices (or rounded?); not meeting along the full length of the mid-line; (of males) covering most to all of the abdomen (Lampyris), or short, exposing several terminal abdominal tergites (Phosphaenus); exposing when long, no more than part of the terminal tergite to at least three complete abdominal tergites; not truncate; rather soft; non-glabrous. Elytra when present, apunctate, irregularly punctate, or each with fewer than 6 longitudinal lines of punctures or impressed striae. Scutellary striole absent. Elytra with epipleura (broad at the base). Wings well developed, or absent or much reduced (in female Lampyris). Wings without an anal lobe. Wings without a medial fleck. Abdominal sternites 6–9; all articulated and moveable. Abdominal segment 8 with apparently functional spiracles, or apparently without functional spiracles. The male external genitalia trilobate.

Adult habitat, ecology. Not predacious (the adults not feeding at all?).

Larvae. Mature larvae small to medium-sized to relatively large. The larvae elongate and more or less parallel-sided. Body somewhat flattened to strongly flattened. Vestiture restricted to fine hairs or setae. The larvae dorsally heavily pigmented or sclerotized; ventrally only very lightly pigmented. The antennae 3 segmented. Stemmata present; on either side of the larval head 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 3 segmented, or 4 segmented. The labium without 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 extending to the underside. The abdomen having functional spiracles on anterior segments (these biforous or bilabiate); with anterior and 8th-segmental spiracles borne at the ends of a series of spiracular tubes. The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The last abdominal segment without cerci.

Larvae free-living and predacious (on snails and worms).

The larvae brown and elongate, tapered fore and aft, with six short legs; with a small head borne beneath the prothorax, with 3-segmented antennae, one ocellus on either side and equipped with channelled mandibles associated with paralyzing and extra-oral digestion of prey.

Classification. Suborder Polyphaga; Infraorder Elateriformia; Superfamily Cantharoidea.

Representation in Britain and Ireland, and worldwide. About 2000 species worldwide (temperate and tropical). 2 species in Britain; genera in Britain 2; Lampyris, Phosphaenus. E.g., Lampyris noctiluca.

General comments. The adult females of Lampyris and both sexes of Phosphaenus are famously luminescent from their distal abdominal sternites. An unusual feature of adult lampyrids is the frequent absence of prococal cavities, so that the procoxae are attached externally.

Illustrations. • Lampyris noctiluca (Glow Worm): B. Ent. 698. • Lampyris noctiluca: B. Ent. 698, legend+text. • Lampyris noctiluca: B. Ent. 698, text cont.. • Lampyris noctiluca and Phosphaenus hemipterus (with Cantharidae): Fowler 4, 111 (1890). • Fowler 4, 111 (1890): original legend. • Lampyris noctiluca, male and female (Janson 190, 191).

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.’.