British insects: the families of Coleoptera
British insects: the families of Coleoptera |
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~Monotomidae-Rhizophaginae.
Root-eating beetles.
General appearance. 1.5–6 mm long. Body length/maximum body width 3–3.4. Elytral length/pronotal length 2.1–2.35. Base of prothorax distinctly narrower than the combined elytral bases. Greatest prothoracic width not narrower or only slightly narrower than the greatest elytral width. Beetles elongate; conspicuously necked to not necked; conspicuously waisted; decidedly short-legged. Upper surfaces of body glabrous or subglabrous; not bristly; with neither scales nor scale-like setae.
Detailed morphology. Beetles prognathous (and the heads of males sharply constricted behind the eyes). Inclination of the head slight. Eyes strongly protuberant; finely facetted. Antennae very short to short; 10 segmented. Antennal scape not swollen. Antennae clubbed. Antennal clubs 2 segmented (tight, spherical). Antennal insertions hidden from above; not in fossae. Mandibular prosthecae well developed. Prothorax shorter than wide to about as long as wide. Pronotal length/maximum pronotal width 1–1.07. Prothorax at its widest not markedly narrower than the adjoining part of the abdomen. Prothorax without notopleural sutures. Metaventrite without a transverse groove. Hind coxae not shaped posteriorly to receive the femur. Tarsal segmentation formula 5, 5, 5, or 5, 5, 4. The tarsi without bilobed segments; without ‘hidden’ segments (the penultimate segment small, the basal two broad with long setae). Front tarsi with as many segments as the mid-tarsi; 4-segmented (males), or 5-segmented (females). Mid-leg tarsi 4-segmented (males), or 5-segmented (females); pentamerous, or pseudotetramerous, or tetramerous. The claws of the mid-leg tarsi not appendaged. The claws of the mid-leg tarsi simple; with an empodium between them (this with no more than two setae). Hind tarsi with as many segments as the mid-tarsi, or with one segment fewer than the mid-tarsi; 4-segmented (males), or 5-segmented (females). Elytral length/maximum width across the elytra 2–2.25. Elytra meeting along the length of the mid-line; covering most to all of the abdomen; exposing no more than part of the terminal tergite to at least one but fewer than three complete abdominal tergites; truncate; punctate- striate. Scutellary striole absent. Elytra glabrous; with epipleura. Elytral epipleura falling short of the elytral tips. Wings well developed. Exposed abdominal sternites 5; all articulated and movable. Abdominal segment 8 apparently without functional spiracles.
Adult habitat, ecology. Land-dwellers; predacious, or not predacious (?); in rotting wood and under bark.
Larvae. Larvae predacious (e.g., on larvae of Scolytinae); in rotting wood and in or under bark.
Classification. Suborder Polyphaga; Superfamily Cucujoidea.
Worldwide and British representation. About 220 species worldwide; genera about 20 (?). 21 species in Britain; genera in Britain 3; Cyanostolus, Monotoma, Rhizophagus. E.g., Rhizophagus bipustulatus.
Illustrations. • Rhizophagus bipustulatus: B. Ent. 579. • Rhizophagus bipustulatus: B. Ent. 579, legend+text. • Rhizophagus bipustulatus: B. Ent. 579, text cont.. • Rhizophagus (4 spp.) and Monotoma (3 spp.), with Trogossitidae, Merophysiidae, etc.: Fowler 3, 91 (1889). • Fowler 3, 91 (1889): original legend.. • Cyanostolus aeneus and Rhizophagus oblongocollis, with unrelated taxa: Fowler Suppl. 13, 1913. • Fowler Suppl. 13, 1913: original legend.. • Rhizophagus bipustulatus (Janson 136).
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’.
