Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz

Melyridae

Including Attalomimidae, Carphuridae, Dasytidae, Gietellidae, Malachiidae, Rhadalidae.

Soft-winged Flower Beetles.

General appearance. 1.4–8 mm long. Body length/maximum body width 1.5–5.55. Elytral length/pronotal length 0.55–5.45. 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 to slender; dorsally flattened; conspicuously necked to not necked; somewhat waisted to conspicuously waisted; not luminescent. Upper surfaces of body glabrous or subglabrous, or non-glabrous; exhibiting stiff, erect, dark bristles, or not bristly; with neither scales nor scale-like setae.

Detailed morphology. The head not covered by the thorax. Eyes strongly protuberant, or not strongly protuberant; bristly, or without bristles. The labrum at least partly visible in antero-dorsal view; labrum mostly moderately to heavily sclerotized. Mandibles without a mola; with well developed prosthecae to without prosthecae. The mandibular apices simple, or bidentate or bilobed. The incisor edges of the mandibles simple, or with a single tooth. The maxillae with distinct galea and lacinia apically to the palp. The apical segment of the maxillary palps cylindrical to fusiform, or somewhat expanded and truncate to subtriangular, or securiform to cultriform (some Rhadalinae only). The apical segment of the labial palps more or less expanded apically, or not expanded apically. Antennae short to about half the insect's head to tail length; 9–11 segmented. Antennal scape swollen, or not swollen. Antennae filiform, or serrate. Antennal insertions visible from above.

Cervical sclerites present. Prothorax shorter than wide, or about as long as wide. Pronotal length/maximum pronotal width 0.55–1.52. The pronotum with lateral keels (pronotal carinae), or without lateral keels (some Malachiinae); keels when present, complete, or incomplete. Prothorax at its widest markedly narrower than the adjoining part of the abdomen, or not markedly narrower than the adjoining part of the abdomen. Prothorax without notopleural sutures. Scutellum conspicuous; not elevated; anteriorly simple; posteriorly broadly rounded or obtusely angulate, or truncate. The prosternal process present, or absent (in some Malachiinae); when present, complete, or incomplete; when applicable, falling short of the mesoventrite to slightly overlapping the mesoventrite. Metaventrite without a transverse groove. The fore-leg coxae countersunk in ‘procoxal cavities’, or attached externally, in the absence of procoxal cavities (some Malachiinae). The fore-leg coxal cavities when applicable, open behind externally; broadly open; when present, medianly confluent, or narrowly separated; strongly transverse, or slightly transverse (some Rhadalinae); 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 contiguous, or narrowly separated; not or scarcely oblique, or markedly oblique; open laterally. Hind-leg coxae contiguous or narrowly separated; extending laterally to meet the elytra, or not markedly extended laterally. Tarsal segmentation formula 5, 5, 5. The tarsi exhibiting bilobed segments, or without bilobed segments; with a tiny penultimate segment hidden by distal lobing of the fourth and fused to the fifth, or without ‘hidden’ segments. Front tarsi with as many segments as the mid-tarsi, or with one segment fewer than the mid-tarsi; 5-segmented. Mid-leg tarsi 5-segmented; pentamerous, or pseudotetramerous, or tetramerous; the penultimate segment not distinctly shorter than the antepenultimate one, or distinctly shorter than the antepenultimate one (some Melachiinae). The claws of the mid-leg tarsi with an appendage, or not appendaged; appendages when present, not or only lightly sclerotized. The claws of the mid-leg tarsi simple, or one-toothed or bifid (toothed or with a fleshy appendage beneath). Hind tarsi with as many segments as the mid-tarsi; 5-segmented.

Elytral length/maximum width across the elytra 0.48–4.4. Elytra meeting along the length of the mid-line; covering most to all of the abdomen, or short, exposing several terminal abdominal tergites; exposing no more than part of the terminal tergite to at least three complete abdominal tergites; rather soft; smooth; without striae. 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. Wings variously with an anal lobe, or without an anal lobe. Wings without a medial fleck. Abdominal sternites 6–7; 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 cucujiform.

Adult habitat, ecology. Land-dwellers; predacious (some, perhaps), or not predacious; on living vegetation and associated with flowers (often around trees or bushes); at least some feeding on pollen.

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; on either side of the larval head 1–5. 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. 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); without spiracular tubes. The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The last abdominal segment with cerci.

Larvae probably predacious, or predacious and not predacious (?); in decaying plant material, in rotting wood, and under bark; all supposedly predatory and/or scavenging.

The larvae are said to resemble those of Cleridae.

Classification. Suborder Polyphaga; Infraorder Cucujiformia; Superfamily Cleroidea.

Representation in Britain and Ireland, and worldwide. At least 550 species worldwide; genera about 60 (?). 22 species in Britain; genera in Britain 10; Anthocomus (Malachiidae), Aplocnemus (Dasytidae), Axinotarsus (Malachiideae), Cerapheles (Malachiidae), Dasytes (Dasytidae), Dolichosoma, Ebaeus, Hypebaeus and Malachius (Malachiidae), Psilothrix. E.g., Malachius marginellus (Spined Soft-beetle).

General comments. Adults small, rather soft-bodied, elongate and flattened, sometimes lacking procoxal cavities. Differing further from Cantharidae in the firmly sclerotized labrum.

Illustrations. • Malachius marginellus (Spined Soft-beetle: B. Ent. 167). • Malachius marginellus: B. Ent. 167, legend+text. • Malachius marginellus: B. Ent. 167, text cont.. • Anthocomus, Axinotarsus, Dasytes, Malachius and Psilothrix: Fowler 4, 114 (1890). • Fowler 4, 114 (1890): original legend. • Dolichosoma lineare, Aplocnemus nigricornis, A. impressus (= nigricornis), with Cleridae and Phloeophilus: Fowler 4, 115 (1890). • Fowler 4, 115 (1890): original legend.. • Malachius barnevelli, with unrelated taxa: Fowler Suppl. 15, 1913. • Fowler Suppl. 15, 1913: original legend.


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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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