Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz


~Pythidae; including Aegialitidae, Colydiidae part, Dacoderidae, Elacatidae, Eurystethidae, Inopeplidae, Othniidae, Tenebrionidae part, Tretothoracidae.

Narrow-waisted Bark-beetles.

General appearance. 2.5–4 mm long. Body length/maximum body width 1.8–6.85. Elytral length/pronotal length 1.5–3.6. 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. Body noticeably widest immediately behind the thorax. Beetles elongate-oval to elongate; not necked; conspicuously waisted. Upper surfaces of body glabrous or subglabrous, or non-glabrous; not bristly, or exhibiting stiff, erect, dark bristles; exhibiting scales or scale-like setae, or with neither scales nor scale-like setae.

Detailed morphology. Beetles equipped with a rostrum, or without a rostrum; prognathous. Eyes strongly protuberant, or not strongly protuberant; without bristles. 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 to without a mola (some Salpinginae); with well developed prosthecae to without prosthecae. The mandibular apices bidentate or bilobed. The incisor edges of the mandibles simple, or 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 (mostly), or somewhat expanded and truncate to subtriangular. The apical segment of the labial palps not expanded apically. Antennae short to about half the insect's head to tail length; 10–11 segmented. Antennal scape not swollen. Antennae filiform, or gradually expanding towards the apex. Antennal insertions visible from above, or hidden from above.

Cervical sclerites absent. Pronotal length/maximum pronotal width 0.56–1.6. The pronotum with lateral keels (pronotal carinae) (Agleninae), or without lateral keels; keels when present, complete. Prothorax without notopleural sutures. Scutellum conspicuous, or highly reduced to absent (Agleninae); when applicable, not elevated; anteriorly simple; posteriorly narrowly rounded or acute, or broadly rounded or obtusely angulate. The prosternal process complete, or incomplete (in some Salpinginae); falling short of the mesoventrite to slightly overlapping the mesoventrite. Metaventrite without a transverse groove. The fore-leg coxae countersunk in ‘procoxal cavities’. The fore-leg coxal cavities open behind externally; broadly open, or narrowly open; variously medianly confluent, or narrowly separated, or quite widely separated; circular to longer than wide; without lateral extensions; 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; closed laterally. Hind-leg coxae contiguous or narrowly separated, or widely separated; not markedly extended laterally; not shaped posteriorly to receive the femur. Tarsal segmentation formula 5, 5, 4. 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, or tetramerous; 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, or one-toothed or bifid. Hind tarsi with as many segments as the mid-tarsi, or with one segment fewer than the mid-tarsi; 4-segmented.

Elytral length/maximum width across the elytra 0.95–2.68. Elytra covering most to all of the abdomen; exposing no more than part of the terminal tergite, or at least three complete abdominal tergites; glossy. 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 10. Scutellary striole present, or absent (some Aegia1itinae). Wings well developed, or absent or much reduced. 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; all articulated and moveable, or comprising both fused and moveable components. Basal abdominal sternites immovably joined when present, 2. Abdominal segment 8 apparently without functional spiracles. The male external genitalia tenebrionoid.

Adult habitat, ecology. On living vegetation (in hedges, or in moss), or under bark; consuming decaying plant material.

Larvae. Mature larvae minute (less than 3 mm long), or small to medium-sized. The larvae elongate and more or less parallel-sided. Body 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 3 segmented. Stemmata present, or absent (Aglenini); on either side of the larval head when present, 5. The frontoclypeal suture between frons and clypeus indistinct or absent. The labrum and head capsule separated by a complete suture. Apices of the mandibles 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; 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 annular or annular-uniforous); without spiracular tubes. The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The last abdominal segment with cerci.

Larvae not predacious, or predacious and not predacious; in divers habitats, in living vegetation (in moss), or in decaying plant material (e.g., in leaf litter and dead and dying twigs), or in rotting wood, or under bark, or associated with fungi (Sphaeriestes), or in dung; Spaeriestes consuming adelgid bugs, and some Aegialatinae feeding at least in part on other small invertebrates.

Classification. Suborder Polyphaga; Infraorder Cucujiformia; Superfamily Tenebrionoidea.

Representation in Britain and Ireland, and worldwide. About 300 species worldwide; genera 45. 10 species in Britain; genera in Britain 5; Lissodema, Rabocerus, Rhinosimus, Salpingus,Sphaeriestes, Vincenzellus, etc. E.g., Rabocerus foveolatus, Vincenzellus viridipennis.

General comments. Small to minute beetles, prognathous and sometimes rostrate.

Illustrations. • Rabocerus gabrieli: B. Ent. 662. • Rabocerus gabrieli: B. Ent. 662, legend+text. • Rabocerus gabrieli: B. Ent. 662, text cont.. • Lissodema, Rhinosimus, Salpingus and Vincenzellus, with Melandryidae and Pytho,: Fowler 5, 147 (1891). • Fowler 5, 147 (1891): original legend.. • Lissodema cursor and Rabocerus foveolatus, with unrelated taxa: Fowler Suppl. 19, 1913. • Fowler Suppl. 19, 1913: original legend.. • Rabocerus gabrieli (Janson 225). • Vincenzellus ruficollis (Rye & Fowler XI3).

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.’.