British Insects: the Families of Coleoptera
British Insects: the Families of Coleoptera |
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= Pelobiidae.
Screech-beetles.
General appearance. 8.5–10 mm long. Body length/maximum body width 1.55–1.58. Elytral length/pronotal length 3.65–4.19. 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 oval to elongate-oval; dorsally strongly convex (convex above and below); not necked. Upper surfaces of body glabrous or subglabrous; not bristly; with neither scales nor scale-like setae.
Detailed morphology. Inclination of the head slight. Eyes strongly protuberant (by contrast with those of other water beetles); without bristles; finely facetted. Antennae very short; 11 segmented; filiform. Antennal insertions visible from above, or hidden from above. Mandibular prosthecae absent.
Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.4–0.5. Prothorax at its widest not markedly narrower than the adjoining part of the abdomen. Prothorax with notopleural sutures. Metaventrite with a transverse groove. Hind coxae immoveable. The tarsi without bilobed segments; without ‘hidden’ segments. Mid-leg tarsi 5-segmented; pentamerous. Claws of the mid-leg tarsi not appendaged. Front tarsi with as many segments as the mid-tarsi; 5-segmented. Hind tarsi with as many segments as the mid-tarsi; 5-segmented; longer than the tibiae, modified for swimming. Tarsal claws simple. Elytral length/maximum width across the elytra 1.22–1.26. Elytra exposing no more than part of the terminal tergite. Scutellary striole absent. Elytra glabrous. Wings well developed.
Visible abdominal sternites 6; immovably joined 3. Abdominal segment 8 with apparently functional spiracles.
Habitat, ecology. Water-beetles; moving in the water by alternate, walking leg movements; predacious.
General comments. Beetles stridulating loudly, by rubbing the apex of the abdomen on a file inside the elytra.
Larvae. Larvae aquatic; predacious.
Classification. Suborder Adephaga; Superfamily Caraboidea.
British representation. Genera 1; 1 species. E.g., Hygrobia hermanni.
Illustrations. • Hygrobia hermanni (Rye & Fowler III5).
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: 9th June 2008. http://delta-intkey.com’.
