Insects of Britain and Ireland: the families of Coleoptera

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L. Watson and M. J. Dallwitz


= Brentidae-Apioninae; including Antliarhinidae, Cyladidae, Eurhynchidae, Nanophyidae.

General appearance. 1.5–3.5 mm long. Body length/maximum body width 1.55–2.45. Elytral length/pronotal length 2.4–3.47. 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. Body noticeably widest immediately behind the thorax. Beetles asymmetric elongate-oval; dorsally strongly convex (abdomen very high-domed); not necked; somewhat waisted. Upper surfaces of body glabrous or subglabrous, or non-glabrous; not bristly; exhibiting scales or scale-like setae, or with neither scales nor scale-like setae.

Detailed morphology. Beetles equipped with a rostrum (this long and curved). Inclination of the head slight to strong. Eyes strongly protuberant, or not strongly protuberant; without bristles. The labrum concealed beneath the clypeus; labrum if recognized as such, mostly moderately to heavily sclerotized. Mandibles without a mola; without prosthecae. The mandibular apices simple, or bidentate or bilobed, or multidentate or multilobed. The incisor edges of the mandibles simple, or with a single tooth. The maxillae with a single apical structure additional to the palp. The maxillary palps if visible, short and rigid; 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; not elbowed; 11 segmented; without a much-elongated scape (despite the long rostrum). Antennal scape not swollen. Antennae clubbed. Antennal clubs 1–3 segmented. Antennal insertions hidden from above; not in fossae.

Cervical sclerites absent. Pronotal length/maximum pronotal width 0.7–1.3. The pronotum without lateral keels. Prothorax without notopleural sutures. Scutellum conspicuous to absent; when applicable, elevated above the mesoscutum in lateral view, or not elevated; anteriorly when present, simple; posteriorly narrowly rounded or acute, or broadly rounded or obtusely angulate. The prosternal process present, or absent; interrupted, or entire; when present and not interrupted, complete, or incomplete; when present and not interrupted, falling short of the mesoventrite. Metaventrite without a transverse groove. The fore-leg coxae countersunk in ‘procoxal cavities’. The fore-leg coxal cavities closed behind externally; broadly closed; medianly confluent; circular to longer than wide; without lateral extensions; broadly closed internally. The mid-leg coxae countersunk in ‘mesocoxal cavities’; separated by less than the shortest diameter of the cavity, or more than the shortest diameter of the cavity (Nanophyinae). The mid-leg coxal cavities contiguous, or narrowly separated, or moderately to widely separated (Nanophyinae); not or scarcely oblique; closed laterally. Hind-leg coxae contiguous or narrowly separated, or widely separated; extending laterally to meet the elytra, or not markedly extended laterally. Tarsal segmentation formula 4, 4, 4. The tarsi exhibiting bilobed segments; with a tiny penultimate segment hidden by distal lobing of the fourth and fused to the fifth. Front tarsi with as many segments as the mid-tarsi; 4-segmented, or 5-segmented (depending on interpretation). Mid-leg tarsi 4-segmented, or 5-segmented; pseudotetramerous; 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, or one-toothed or bifid; without an associated empodium. Hind tarsi with as many segments as the mid-tarsi; 4-segmented, or 5-segmented.

Elytral length/maximum width across the elytra 1.1–1.83. Elytra exposing no more than part of the terminal tergite. Elytra with six or more longitudinal lines of punctures, or 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, 9, or 10. Scutellary striole absent. Wings well developed. Wings with an anal lobe, or without an anal lobe. Wings without a medial fleck. Abdominal sternites 4–5, or 5; comprising both fused and moveable components. Basal abdominal sternites immovably joined 2 (the two basal sternites enlarged and fused). Abdominal segment 8 apparently without functional spiracles. The male external genitalia cucujiform.

Adult habitat, ecology. On living vegetation; phytophagous.

Larvae. Mature larvae minute (less than 3 mm long), or small to medium-sized. The larvae elongate and more or less parallel-sided to oblong to ovate; C-shaped in lateral view. Body circular in cross-section, or 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 1 segmented. Stemmata present; on either side of the larval head 1, or 2. The frontoclypeal suture between frons and clypeus distinct. The labrum and head capsule separated by a complete suture. Apices of the mandibles bilobed or bidentate. The maxillary palps 2 segmented. The labium without ligula between the palps. Labial palps present and segmented; 1 segmented. Mesothoracic legs much reduced or absent; 0 segmented, or 1 segmented. Visible abdominal segments 10. Tergum 9 of the abdomen entirely dorsal. The abdomen having functional spiracles on anterior segments (these annular-uniforous); without spiracular tubes. The abdominal apex without a respiratory chamber. Abdominal tergum 8 without amature. The posterior segments without swimming hairs. The last abdominal segment without cerci.

Larvae phytophagous.

Larvae with legs reduced or absent, antennae 1- or 2-segmented.

Classification. Suborder Polyphaga; Superfamily Curculionoidea.

Representation in Britain and Ireland, and worldwide. About 2100 species worldwide. 73 species in Britain; genera in Britain 2; Apion (with numerous subgenera raised to generic rank in recent treatments), Nanophyes (Nanophyidae). E.g., Apion difforme (Eccentric Apion Weevil).

Illustrations. • Apion difforme (Eccentric Apion Weevil: B. Ent. 211). • Apion difforme (details, B. Ent. 211). • Apion difforme: B. Ent. 211, legend+text. • Apion difforme: B. Ent. 211, text cont.. • 13 species of Apion: Fowler 5, 154 (1891). • Fowler 5, 154 (1891): original legend. • 13 species of Apion: Fowler 5, 155 (1891). • Fowler 5, 155 (1891): original legend.. • 13 species of Apion: Fowler 5, 156 (1891). • Fowler 5, 156 (1891): orginal legend.. • Nanopyes gracilis and N. marmoratus (as N. lythri), with Curculionidae: Fowler 5, 171 (1891). • Fowler 5, 171 (1891): original legend.. • Apion difficile, with asorted unrelated taxa: Fowler Suppl. 19, 1913. • Fowler Suppl. 19, 1913: 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.’.