British insects: the families of Coleoptera
British insects: the families of Coleoptera |
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~ Dascillidaes. lat., including Eubriidae, Psephenoididae.
Water-penny beetles.
General appearance. 1.5–2 mm long. Body length/maximum body width 1.35–1.77. Elytral length/pronotal length 2.8–4.57. 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, or distinctly narrower than greatest elytral width. Beetles oval; dorsally strongly convex; not necked; not waisted; black or dark brown. Upper surfaces of body non-glabrous; not bristly; with neither scales nor scale-like setae.
Detailed morphology. Inclination of the head slight to strong. Eyes strongly protuberant; without bristles; finely facetted. Antennae long, but not exceeding the insect’s head to tail length; 11 segmented. Antennal scape not swollen. Antennae finely serrate. Mandibular prosthecae absent. Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.3–0.55. 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 5, 5, 5. The tarsi 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 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. Hind tarsi with as many segments as the mid-tarsi; 5-segmented. Elytral length/maximum width across the elytra 1.05–1.38. Elytra exposing no more than part of the terminal tergite; hard. Scutellary striole present, or absent. Elytra non-glabrous (shortly, finely and densely hairy). Wings well developed. Exposed abdominal sternites 5–6; comprising both fused and movable components; immovably joined 3. Abdominal segment 8 apparently without functional spiracles.
Adult habitat, ecology. Water-beetles to land-dwellers (or sub-aquatic: found in moist places, sometimes in water); moving in the water by alternate, walking leg movements.
Larvae. Larvae aquatic (found clinging to stones); predacious (e.g., on other larvae), or not predacious; when not predaceous, phytophagous (e.g., on algae), or coprophagous.
Classification. Suborder Polyphaga; Infraorder Elateriformia; Superfamily Dryopoidea.
Worldwide and British representation. About 275 species worldwide; genera about 35. 1 species in Britain (E. palustris); genera in Britain 1; Eubria.
General comments. Oval to coin-shaped, often coppery beetles, with deeply furrowed elytra..
Illustrations. • Eubria palustris: Fowler 4 (1890). • Eubria palustris (from Joy). Limnichus pygmaeus (Limnichidae). Eubria palustris (Psephenidae).
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’.
