Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz

Melandryidae

= Serropalpidae; including Tetratomidae part.

False Darkling Beetles.

General appearance. 3–15 mm long. Body length/maximum body width 1.75–4.45. Elytral length/pronotal length 2.47–5.6. 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. Beetles oval to elongate; not necked; not waisted to somewhat waisted. Upper surfaces of body glabrous or subglabrous, or non-glabrous; not bristly; with neither scales nor scale-like setae.

Detailed morphology. Beetles not prognathous. Eyes not strongly protuberant (not prominent); bristly, or 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 (Hallomeninae); with well developed prosthecae. The mandibular apices bidentate or bilobed. The incisor edges of the mandibles simple, or with a single tooth (some Melandryinae). 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 (being especially variable in Melandryinae). The apical segment of the labial palps more or less expanded apically (Osphyinae), or not expanded apically. Antennae short to long, but not exceeding the insect’s head to tail length; (10–)11 segmented. Antennal scape not swollen. Antennae filiform to gradually expanding towards the apex. Antennal insertions visible from above, or hidden from above; not hidden by lateral extensions of the frons.

Cervical sclerites present (mostly), or absent (some Melandryinae). Pronotal length/maximum pronotal width 0.4–0.95. The pronotum with lateral keels (pronotal carinae); keels complete, or incomplete (in some Melandryinae). Prothorax with neither produced front corners nor serrated sides. Prothorax without notopleural sutures. Scutellum conspicuous, or absent (some Melandryinae); when applicable, not elevated; anteriorly simple; posteriorly narrowly rounded or acute (some Osphyinae), or broadly rounded or obtusely angulate, or truncate. The prosternal process complete; falling short of the mesoventrite, or 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; variously medianly confluent, or narrowly separated, or quite widely separated; strongly transverse (Osphyinae), or slightly transverse (some Melandryinae), or circular to longer than wide; without lateral extensions; internally closed by a slender bar (some Melandryinae), or broadly closed internally. The mid-leg coxae countersunk in ‘mesocoxal cavities’; separated by less than the shortest diameter of the cavity. The mid-leg coxal cavities contiguous (some Melandryinae), or narrowly separated, or moderately to widely separated; not or scarcely oblique (some Melandryinae), or markedly oblique; open laterally. Hind-leg coxae contiguous or narrowly separated; extending laterally to meet the elytra (Melandryinae), or not markedly extended laterally; not shaped posteriorly to receive the femur. Tarsal segmentation formula 5, 5, 4, or 4, 4, 4. The tarsi exhibiting bilobed segments, or without 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, or distinctly shorter than the antepenultimate one (some Melandryinae). 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 one segment fewer than the mid-tarsi; 4-segmented.

Elytral length/maximum width across the elytra 1.35–3.53. Elytra individually distinctly tapered to their apices; covering most to all of the abdomen; exposing no more than part of the terminal tergite; hard; non-glabrous (finely hairy). Elytra 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, 10, or 11. Scutellary striole present (Hallomeninae), or absent (mostly). Elytra with epipleura. Elytral epipleura reaching to the tips of the elytra, or falling short of the elytral tips (?). Wings well developed. 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. Not predacious (?); on living vegetation, in rotting wood, under bark, and associated with fungi (and in old wood).

Larvae. Mature larvae minute (less than 3 mm long) to relatively large. The larvae elongate and more or less parallel-sided. Body circular in cross-section, or somewhat flattened. Vestiture restricted to fine hairs or setae. The larvae dorsally heavily pigmented or sclerotized (Eustrophinae), or dorsally only very lightly pigmented or sclerotized; ventrally only very lightly pigmented. The antennae 3 segmented. Stemmata present, or absent; on either side of the larval head when present 2 (Osphyinae), or 5. The frontoclypeal suture between frons and clypeus indistinct or absent (Eustrophinae), or distinct. The labrum and head capsule separated by a complete suture. Apices of the mandibles with a single lobe or tooth, or 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, 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 9, or 10. Tergum 9 of the abdomen entirely dorsal, or entirely dorsal to extending to the underside. The abdomen having functional spiracles on anterior segments (these annular, annular-uniforous or annular-biforous); without spiracular tubes. The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The last abdominal segment with cerci, or without cerci.

Larvae not predacious (?); in living vegetation, in rotting wood, under bark, and associated with fungi; seemingy mainly mycetophagous (commonly in fungus-infected wood polypore fruit bodies).

Classification. Suborder Polyphaga; Infraorder Cucujiformia; Superfamily Tenebrionoidea.

Representation in Britain and Ireland, and worldwide. About 1200 species worldwide; genera about 100. 18 species in Britain; genera in Britain 11; Abdera, Anisoxya, Conopalpus, Hallomenus, Hypulus, Melandrya, Orchesia, Osphya, Phloiotrya, Xylita, Zilora. E.g., Abdera flexuosa (Banded Hallomenus); Abdera biflexuosa (Double-banded Hyplexus); Conopalpus testaceus; Orchesia undulata (Banded Orchesia Jumping Beetle); Osphya bipunctata (Twin-spotted Nothus, and var.).

General comments. Small to moderately sized, elongate-ovate beetles, bodies finely pubescent.

Illustrations. • Abdera flexuosa Curtis (Banded Hallomenus: B. Ent. 474). • Abdera flexuosa (details, B. Ent. 474). • Abdera flexuosa: B. Ent. 474, legend+text. • Abdera flexuosa: B. Ent. 474, text cont.. • Abdera biflexuosa (Curtis): Double-banded Hyplexus; B. Ent. 255. • Abdera biflexuosa: B. Ent. 255, legend+text. • Abdera biflexuosa: B. Ent. 255, text cont.. • Melandrya dubia (Scarce Melandrya, probably alien): B. Ent. 155). • Melandrya dubia: B. Ent. 155, legend+text. • Melandrya dubia: B. Ent. 155, text cont.. • Orchesia undulata (Banded Jumping-beetle: B. Ent. 197). • Orchesia undulata: B. Ent. 197, legend+text. • Orchesia undulata: B. Ent. 197, text cont.. • Osphya bipunctata (Twin-spotted Nothus, and var.): B. Ent. 538. • Osphya bipunctata: B. Ent. 538, legend+text. • Osphya bipunctata: B. Ent. 538, text cont.. • Abdera (4 spp.), Anisoxya, Conopalpus, Hallomenus, Melandrya (2 spp.), Orchesia (3 spp.): Fowler 5, 146 (1891). • Fowler 5, 146 (1891): original legend. • Hypulus, Osphya, Phloiotrya, Xylita, Zilora (with Salpingidae and Pytho): Fowler 5, 147 (1891). • Fowler 5, 147 (1891): original legend.. • Abdera affinis, with Chrysomelidae and Tenebrionidae: Fowler Suppl. 18, 1913. • Fowler Suppl. 18, 1913: original legend.. • Conopalpus testaceus (Janson157).


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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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