Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz


= Atopidae; including Karumiidae.

Soft-bodied Plant Beetles.

General appearance. 9–11 mm long. Body length/maximum body width 1.85–4.21. Elytral length/pronotal length 2–7.98. Base of prothorax not or scarcely narrower than the combined elytral bases to distinctly narrower than the combined elytral bases. Greatest prothoracic width not narrower or only slightly narrower than the greatest elytral width to distinctly narrower than greatest elytral width. Body not noticeably widest either behind the thorax, or at the rear. Beetles elongate; dorsally flattened to dorsally somewhat convex; not necked; somewhat waisted; dull beetles, “brownish black, with light brown pubescence”, or “orange brown, completely covered with dense, flattened light yellow hairs”. 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 somewhat prognathous to not prognathous. Inclination of the head slight. Eyes strongly protuberant; without bristles; finely facetted. Ocelli absent. The labrum at least partly visible in antero-dorsal view; labrum mostly moderately to heavily sclerotized. Mandibles without a mola; without prosthecae. The mandibular apices simple. The incisor edges of the mandibles with a single tooth. The maxillae with distinct galea and lacinia apically to the palp. The maxillary palps normal, flexible; apical segment of the maxillary palps cylindrical to fusiform. The apical segment of the labial palps not expanded apically. Antennae long, but not exceeding the insect’s head to tail length; 11 segmented; filiform. Antennal insertions visible from above to hidden from above; not in fossae.

Cervical sclerites present. Prothorax shorter than wide (widest posteriorly). Pronotal length/maximum pronotal width 0.52–0.75. The pronotum with lateral keels (pronotal carinae); keels complete. Prothorax at its widest markedly narrower than the adjoining part of the abdomen to not markedly narrower than the adjoining part of the abdomen; with neither produced front corners nor serrated sides. Prothorax without notopleural sutures. Scutellum conspicuous; elevated above the mesoscutum in lateral view; anteriorly simple; posteriorly broadly rounded or obtusely angulate. The prosternal process present; complete; slightly overlapping the mesoventrite. Metaventrite with a transverse groove. The fore-leg coxae countersunk in ‘procoxal cavities’. The fore-leg coxal cavities open behind externally; broadly open; narrowly separated; strongly transverse; without lateral extensions; internally open. The mid-leg coxae countersunk in ‘mesocoxal cavities’; separated by less than the shortest diameter of the cavity. The mid-leg coxal cavities narrowly separated; not or scarcely oblique; open laterally. Hind-leg coxae contiguous or narrowly separated; extending laterally to meet the elytra; posteriorly shaped to receive the retracted femur (transversely excavated). Tarsal segmentation formula 5, 5, 5. The tarsi exhibiting bilobed segments (segments 2 to 4); 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; without an associated empodium. Hind tarsi with as many segments as the mid-tarsi; 5-segmented.

Elytral length/maximum width across the elytra 1.21–3.74. Elytra not individually tapered; exposing no more than part of the terminal tergite (usually), or at least three complete abdominal tergites; dull; non-glabrous. Elytra with six or more longitudinal lines of punctures, 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, 12 or more. Scutellary striole absent. Wings well developed. Wings without an anal lobe. Wings without a medial fleck. Abdominal sternites 5–6; all articulated and moveable, or comprising both fused and moveable components. Basal abdominal sternites immovably joined when present, 2. Abdominal segment 8 with apparently functional spiracles. The male external genitalia trilobate.

Adult habitat, ecology. Probably not predacious (?); on living vegetation and associated with flowers.

Larvae. Mature larvae small to medium-sized. The larvae elongate and more or less parallel-sided. Body circular in cross-section to 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 2 segmented, or 3 segmented. Stemmata absent. The frontoclypeal suture between frons and clypeus indistinct or absent. The labrum and head capsule partly fused, with an incomplete suture. Apices of the mandibles bilobed or bidentate. The maxillary palps 3 segmented. The labium with a short 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 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 posterior segments without swimming hairs. The last abdominal segment with cerci, or without cerci.

Larvae commonly found under stones and in the soil; phytophagous and consuming decaying plant material (especially on plant roots and organic matter in soil).

The larvae C-shaped like those of scarabs, with rather long 3-segmented antennae and a reduced abdominal segment 10 lying under the large segment 9.

Classification. Suborder Polyphaga; Infraorder Elateriformia; Superfamily Dascilloidea.

Representation in Britain and Ireland, and worldwide. About 80 species worldwide; genera 15. 1 species in Britain; genera in Britain 1; Dascillus. E.g., Dascillus cervinus.

General comments. Adults more elongate than Scirtidae, the thorax with obvious side-margins.

Illustrations. • Dascillus cervinus (bent216). • Dascillus cervinus (details, B. Ent. 216). • Dascillus cervinus: B. Ent. 216, legend+text. • Dascillus cervinus: B. Ent. 216, text cont.. • Dascillus cervinus (with Elateridae and Scirtidae): Fowler 4, 109 (1890). • Fowler 4, 109 (1890): original legend..

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.’.