Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz

Leptinidae

~ Leiodidae-Platypsillinae p.p.

General appearance. 2–2.5 mm long. Body length/maximum body width 1.7–1.95. Elytral length/pronotal length 1.6–1.9. 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. Body not noticeably widest either behind the thorax, or at the rear. Beetles oval to elongate-oval; dorsally flattened; not necked; not waisted; neither particularly long- nor short-legged to decidedly short-legged; brownish orange. Upper surfaces of body non-glabrous (pubescent); not bristly; with neither scales nor scale-like setae.

Detailed morphology. Beetles not prognathous. Inclination of the head slight. Eyes absent (in British representatives). Ocelli absent. The labrum at least partly visible in antero-dorsal view; labrum mostly moderately to heavily sclerotized. Mandibles without a mola; with well developed prosthecae. The mandibular apices bidentate or bilobed. The incisor edges of the mandibles simple. The maxillae with distinct galea and lacinia apically to the palp. The apical segment of the maxillary palps cylindrical to fusiform. The apical segment of the labial palps not expanded apically. Antennae short to about half the insect's head to tail length; 11 segmented; filiform to gradually expanding towards the apex. Antennal insertions hidden from above.

Cervical sclerites absent. Prothorax shorter than wide (widened posteriorly). Pronotal length/maximum pronotal width 0.55–0.65. The pronotum with lateral keels (pronotal carinae); keels complete. Prothorax at its widest not markedly narrower than the adjoining part of the abdomen. Prothorax without notopleural sutures. Scutellum conspicuous; not elevated; anteriorly simple; posteriorly narrowly rounded or acute, or broadly rounded or obtusely angulate. The prosternal process complete, or incomplete; 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; quite widely separated; circular to longer than wide; with narrow lateral extensions, or 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, or moderately to widely separated; not or scarcely oblique; open laterally. Hind-leg coxae contiguous or narrowly separated; not much enlarged; not markedly extended laterally. 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. Hind tarsi with as many segments as the mid-tarsi; 5-segmented.

Elytral length/maximum width across the elytra 1–1.1. Elytra covering most to all of the abdomen; exposing no more than part of the terminal tergite. The pygidium at least partly exposed beyond the long elytra, or entirely concealed by the ends of the elytra even when viewed from behind. Elytra not truncate; non-glabrous. Elytra apunctate, irregularly punctate, or each with fewer than 6 longitudinal lines of punctures or impressed striae. Scutellary striole absent. Wings absent or much reduced. Wings without an anal lobe. Abdominal sternites 6; comprising both fused and moveable components. Abdominal segment 8 with apparently functional spiracles. The male external genitalia staphylinoid.

Adult habitat, ecology. On shed fur or feathers (scavenging in rodents’ burrows and birds’ nests).

Larvae. Mature larvae minute (less than 3 mm long). 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 only very lightly pigmented or sclerotized; ventrally only very lightly pigmented. The antennae 3 segmented. Stemmata absent. The frontoclypeal suture between frons and clypeus indistinct or absent. The labrum and head capsule separated by a complete suture. Apices of the mandibles with a single lobe or tooth, or bilobed or bidentate. The maxillary palps 3 segmented. The labium with a short ligula between the palps, or with a ligula at least as long as 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 (annular); without spiracular tubes. The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The last abdominal segment with cerci.

Larvae in shed fur or feathers (in nests of birds and mice); feeding on dried animal remains and coprophagous (scavenging).

Classification. Suborder Polyphaga; Infraorder Staphyliniformia; Superfamily Staphilinoidea.

Representation in Britain and Ireland, and worldwide. 3 species worldwide (or more?); genera 1 (Leptinus). 1 species in Britain (L. testaceus); genera in Britain 1; Leptinus.

General comments. Small beetles with long, slender antennae, completely lacking eyes; a northern hemisphere genus of few species, commensals with mammals.

Illustrations. • Leptinus testaceus (from Joy). Leptinus testaceus. • Leptinus testaceus, with Clambidae and Leiodidae: Fowler 3, 71 (1889). • Fowler 3, 71 (1889): 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. delta-intkey.com’.

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