Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz

Merophysiidae

~Endomychidae-Merophysiinae.

General appearance. 1–1.7 mm long. Body length/maximum body width 1.4–2.5. Elytral length/pronotal length 1.9–2.65. 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. Beetles elongate-oval; not necked; conspicuously waisted; brown or yellowish. Upper surfaces of body glabrous or subglabrous, or non-glabrous; not bristly; with neither scales nor scale-like setae.

Detailed morphology. Eyes strongly protuberant, or not strongly protuberant; without bristles; coarsely facetted. Labrum mostly moderately to heavily sclerotized. Mandibles with a well developed mola. 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. Antennae short; 11 segmented. Antennal scape not swollen. Antennae clubbed (the club elongate). Antennal insertions visible from above, or hidden from above.

Cervical sclerites present, or absent. Pronotal length/maximum pronotal width 0.4–1.05. The pronotum with lateral keels (pronotal carinae); keels complete. Prothorax without notopleural sutures. Scutellum conspicuous to highly reduced, or absent; when applicable, not elevated; anteriorly simple; posteriorly broadly rounded or obtusely angulate, or truncate. The prosternal process complete; falling short of the mesoventrite to moderately or strongly 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 to narrowly open; narrowly separated, or quite widely separated; circular to longer than wide; with narrow lateral extensions, or without lateral extensions; broadly closed internally. The mid-leg coxal cavities closed laterally. Hind-leg coxae widely separated; not much enlarged; not markedly extended laterally; not shaped posteriorly to receive the femur. Tarsal segmentation formula 3, 3, 3. The tarsi without bilobed segments; without ‘hidden’ segments. Front tarsi with as many segments as the mid-tarsi; 3-segmented. Mid-leg tarsi 3-segmented; trimerous; 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; 3-segmented.

Elytral length/maximum width across the elytra 1–1.75. Elytra covering most to all of the abdomen; exposing no more than part of the terminal tergite; hard; glossy; smooth; glabrous; without striae (at least, with a well marked sutural stria only). Elytra apunctate, irregularly punctate, or each with fewer than 6 longitudinal lines of punctures or impressed striae. Scutellary striole absent. Wings well developed, or absent or much reduced; fringed with long hairs on the hind margin, or not fringed. Wings without an anal lobe. Wings with a medial fleck; the medial fleck not bisected by a vein. Abdominal sternites 5–6; all articulated and moveable. Abdominal segment 8 apparently without functional spiracles. The male external genitalia cucujiform.

Adult habitat, ecology. Land-dwellers; in decaying plant material and associated with fungi; mycetophagous (on moulds).

Larvae. Mature larvae minute (less than 3 mm long). 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 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 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 without cerci.

Larvae in decaying plant material and associated with fungi; mycetophagous (on moulds).

Classification. Suborder Polyphaga; Superfamily Cucujoidea.

Representation in Britain and Ireland, and worldwide. Genera 12. 3 species in Britain; genera in Britain 1; Holoparamecus Curtis.

Illustrations. • Holoparamecus depressus Curtis: B. Ent. 614. • Holoparamecus depressus Curtis: B. Ent. 614, legend+text. • Holoparamecus depressus Curtis: B. Ent. 614, text cont.. • Holoparamecus caularum, with unrelated taxa: Fowler Suppl. 13, 1913. • Fowler Suppl. 13, 1913: original legend.. • Holoparamecus singularis (Janson 132). • Biphyllus (from Joy).


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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