British insects: the families of Coleoptera
British insects: the families of Coleoptera |
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Mud-beetles.
General appearance. 2.5–5 mm long. Body length/maximum body width 1.7–3.05. Elytral length/pronotal length 2.2–3.53. Base of prothorax not or scarcely narrower than the combined elytral bases. Greatest prothoracic width not narrower or only slightly narrower than the greatest elytral width. Beetles elongate; without ventral body cavities for reception of the legs; not necked; conspicuously waisted. Upper surfaces of body non-glabrous; not bristly; with neither scales nor scale-like setae.
Detailed morphology. Beetles prognathous. Inclination of the head slight. Eyes not strongly protuberant; without bristles; finely facetted. Antennae very short; strongly asymmetric; (9–)11 segmented. Antennal scape not swollen. Antennae clubbed. Antennal clubs 7 segmented (serrate); preceded by a cupule, or without a cupule. Antennal insertions visible from above; not in fossae. Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.52–0.82. Prothorax at its widest not markedly narrower than the adjoining part of the abdomen. Prothorax without notopleural sutures. Metaventrite with a transverse groove. Hind coxae posteriorly shaped to receive the retracted femur; with a steep transverse declivity against which the femur retracts. Tarsal segmentation formula 4, 4, 4. The tarsi without bilobed segments; without ‘hidden’ segments (but the terminal segment about half as long as the basal three together). Front tarsi with as many segments as the mid-tarsi; 4-segmented. Mid-leg tarsi 4-segmented; tetramerous. 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; 4-segmented. Elytral length/maximum width across the elytra 1.18–2.3. Elytra exposing no more than part of the terminal tergite; not truncate; hard. Scutellary striole absent. Elytra non-glabrous (densely hairy). Wings well developed, or absent or much reduced. Abdominal tergites 10. Exposed abdominal sternites 5; comprising both fused and movable components; immovably joined 3. Abdominal segment 8 with apparently functional spiracles.
Adult habitat, ecology. Land-dwellers; not predacious; phytophagous; in living vegetation, or in decaying plant material (found in stiff mud at the sides of ponds and streams).
Larvae. Larvae seemingly non-aquatic; not predacious; phytophagous; on living vegetation, or in decaying plant material (in mud). The larvae elongate, with rather distended thoracic segments, well developed legs, and 10 visible abdominal segments.
Classification. Suborder Polyphaga; Infraorder Elateriformia; Superfamily Dryopoidea.
Worldwide and British representation. About 250 species worldwide; genera 5–20 (depending on taxonomic opinion). 8 species in Britain; genera in Britain 1; Heterocerus. E.g., Heterocerus obsoletus (Largest Heterocerus).
Illustrations. • Heterocerus obsoletus Curtis (Largest Heterocerus: B. Ent. 224). • Heterocerus obsoletus (details, B. Ent. 224). • Heterocerus obsoletus (B. Ent. 224, legend+text). • Heterocerus obsoletus (B. Ent. 224, text cont.). • Heterocerus fenestratus, H. flexuosus, H. fusculus and H. maritimus: (with Elmidae and Dryopidae): Fowler 3, 98 (1889). • Fowler 3, 98 (1889): 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. British insects: the families of Coleoptera. Version: 2nd January 2012. http://delta-intkey.com’.
