Insects of Britain and Ireland: the families of Coleoptera
General appearance. 1.3–2.5 mm long. Base of prothorax not or scarcely narrower than the combined elytral bases. Greatest prothoracic width distinctly narrower than greatest elytral width. Body not noticeably widest either behind the thorax, or at the rear. Beetles oval to elongate-oval; dorsally somewhat convex; not necked; conspicuously waisted; decidedly short-legged; brown. Upper surfaces of body non-glabrous; not bristly; with neither scales nor scale-like setae.
Detailed morphology. Beetles not prognathous. Inclination of the head slight. Eyes strongly protuberant; bristly, or without bristles; coarsely facetted. Ocelli absent. The labrum at least partly visible in antero-dorsal view; labrum mostly moderately to heavily sclerotized. Mandibles with a well developed mola; with well developed prosthecae. The mandibular apices bidentate or bilobed. 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 more or less expanded apically. Antennae short; 11 segmented; hairy. Antennal scape somewhat swollen. Antennae clubbed. Antennal clubs 3 segmented; without a cupule. Antennal insertions hidden from above.
Cervical sclerites present. Prothorax shorter than wide. Pronotal length/maximum pronotal width about 0.5–0.7. The pronotum with lateral keels (pronotal carinae); keels complete. Prothorax at its widest not markedly narrower than the adjoining part of the abdomen. Hind corners of the thorax not extended rearwards into sharp points. Scutellum conspicuous; elevated above the mesoscutum in lateral view; anteriorly simple; posteriorly broadly rounded or obtusely angulate. The prosternal process complete; slightly overlapping the mesoventrite. The fore-leg coxae countersunk in procoxal cavities. The fore-leg coxal cavities closed behind externally; broadly closed; quite widely separated; slightly 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 moderately to widely separated; not or scarcely oblique; closed laterally. Hind-leg coxae widely separated; not markedly extended laterally. Tarsal segmentation formula 5, 5, 5. Mid-leg tarsi pentamerous; the penultimate segment 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 about 1.3–1.7. Elytra exposing no more than part of the terminal tergite. The pygidium entirely concealed by the ends of the elytra even when viewed from behind. Elytra not truncate; glossy; non-glabrous; striate (with 10 complete rows of fine punctures). 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, 10. Scutellary striole absent. Elytra with epipleura to without epipleura. Wings well developed. Wings with an anal lobe, or without an anal lobe. Wings with a medial fleck; the medial fleck not bisected by a vein. Abdominal sternites 5; in the British representative, all articulated and moveable. Abdominal segment 8 apparently without functional spiracles. The male external genitalia cucujiform.
Adult habitat, ecology. In decaying plant material and associated with fungi; consuming decaying plant material and mycetophagous.
Larvae. Mature larvae minute (less than 3 mm long), or small to medium-sized. The larvae elongate and more or less parallel-sided. Vestiture not restricted to fine hairs or setae. The larvae dorsally heavily pigmented or sclerotized, or dorsally only very lightly pigmented or sclerotized; ventrally only very lightly pigmented. The antennae 3 segmented. Stemmata present; on either side of the larval head 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 trilobed or tridentate. 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 extending to the underside. The abdomen having functional spiracles on anterior segments (these annular-biforous); 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 with cerci.
Larvae in or associated with fungi (?), or in decaying plant material; consuming decaying plant material and mycetophagous (e.g., on molds).
Classification. Suborder Polyphaga; Infraorder Cucujiformia; Superfamily Cucujoidea.
Representation in Britain and Ireland, and worldwide. About 400 species worldwide. 1 species in Britain; genera in Britain 1; Cryptophilus (C. integer).
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’.