British Insects: the Families of Coleoptera
British Insects: the Families of Coleoptera |
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General appearance. 2–4.5 mm long. Body length/maximum body width 1.45–2.5. Elytral length/pronotal length 3.24–4.05. 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; conspicuously necked to not necked; not waisted to somewhat waisted; yellowish. Upper surfaces of body glabrous or subglabrous, or non-glabrous; not bristly; with neither scales nor scale-like setae.
Detailed morphology. Inclination of the head slight. Eyes not strongly protuberant; without bristles; coarsely facetted. Antennae very short to short; 11 segmented; filiform. Antennal insertions visible from above; not in fossae. Mandibular prosthecae well developed, or absent.
Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.43–0.66. Prothorax at its widest not markedly narrower than the adjoining part of the abdomen. Prothorax with notopleural sutures. Metaventrite with a transverse groove, or without a transverse groove. Hind coxae immoveable; expanded and plate-like (when legs retracted, covering the basal abdominal sternites, as well as the hind femora). The tarsi without ‘hidden’ segments. Mid-leg tarsi 5-segmented (and modified for swimming, cf. the hind pair); 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; modified for swimming (via long hairs). Tarsal claws simple. Elytral length/maximum width across the elytra 1.15–1.52. Elytra exposing no more than part of the terminal tergite; darkly, conspicuously striate. Scutellary striole present, or absent. Wings well developed, or absent or much reduced.
Visible abdominal sternites 4–6; immovably joined 0, or 2, or 3. Abdominal segment 8 with apparently functional spiracles.
Habitat, ecology. Water-beetles; partly predacious; phytophagous (mainly on algae?), or consuming decaying plant material.
General comments. Boat-shaped beetles, the scutellum not visible; crawling under water, and swimming, via alternate leg movements.
Larvae. Larvae aquatic; predacious (with suctorial mandibles).
Classification. Suborder Adephaga; Superfamily Caraboidea.
British representation. Genera 3; 18 species. E.g., Haliplus obliquus.
Illustrations. • Haliplus obliquus (Rye & Fowler III4).
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’.
