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| Insects of Britain and Ireland: water beetles |
Including Cassididae, Crioceridae, Hispidae, etc.
Leaf-beetles; including the Colorado Beetle and the Bloody-nosed Beetle.
Adults. Beetles terrestrial (but many, including some with truly aquatic larvae, are associated with vegetation around the water’s edge); if inundated, walking in water or free-swimming by conventional ambulatory motion of the legs, not diving strongly; if inundated, moving in the water by alternate, walking leg movements; 1–18 mm long; round to elongate; not necked; often brightly coloured, often conspicuously spotted or metallic; without a rostrum.
Eyes bristly, or without bristles. Mandibles with a well developed mola, or with a reduced mola, or without a mola. The mandibular apices simple, or bidentate or bilobed, or multidentate or multilobed. The incisor edges of the mandibles simple, or with a single tooth, or with two or more teeth. The maxillae with distinct galea and lacinia apically to the palp; without stylet-like lobes. The apical segment of the maxillary palps cylindrical to fusiform, or somewhat expanded and truncate to subtriangular, or securiform to cultriform. The apical segment of the labial palps more or less expanded apically, or not expanded apically. Antennae short to long, but not exceeding the insect’s head to tail length; 3 segmented, or 7–11 segmented; filiform, or gradually expanding towards the apex, or serrate.
Prothorax without notopleural sutures. Metaventrite without a transverse groove. The prosternal process complete; falling short of the mesoventrite to slightly overlapping the mesoventrite, or moderately or strongly overlapping the mesoventrite to concealing most or all of the mesoventrite. The fore-leg coxal cavities broadly open, or narrowly open, or narrowly closed, or broadly closed; medianly confluent to quite widely separated; strongly transverse, or slightly transverse, or circular to longer than wide; with narrow lateral extensions, or without lateral extensions; internally open, or internally closed by a slender bar, or broadly closed internally. Tarsal segmentation formula 4, 4, 4. Some tarsi with a tiny penultimate segment hidden by distal lobing of the fourth and fused to the fifth. Mid-leg tarsi pseudotetramerous.
Wings with an anal lobe, or without an anal lobe; with a medial fleck, or without a medial fleck; the medial fleck when present, not bisected by a vein. The male external genitalia cucujiform, or chrysomeloid.
Adults not predacious; phytophagous (often on leaves or pollen); in living vegetation.
Larvae. The larvae scarabaeiform; elongate and more or less parallel-sided; C-shaped in lateral view; vestiture restricted to fine hairs or setae; only very lightly pigmented or sclerotized; only very lightly pigmented. The antennae 3 segmented; 0.15–0.5 x the head width. Stemmata fewer than 6 (five). Frontoclypeal suture between frons and clypeus distinct. The labrum and head capsule separated by a complete suture. Apices of the mandibles bilobed or bidentate. The maxillary palps 3 segmented. The labium with a ligula at least as long as the palps. The labial palps 3 segmented. The mesothoracic legs 4 segmented; with 1 movable claw. Visible abdominal segments 10. Tergum 9 of the abdomen entirely dorsal.
The larvae aquatic (those of Donaciinae), or non-aquatic. The abdomen in Donaciinae, with functional spiracles confined to the the eighth segment; with the spiracles on the eighth segment borne at the ends of spiracular tubes. The larvae without gills (the aquatic forms obtain air when submerged by piercing the tissues of the helophytic plants on which they feed with modified, spine-like 8th spiracles). Abdominal tergum 8 bearing a pair of processes, each with an apical spiracle (Donaciinae), or without amature. The larvae not predacious; phytophagous (Donaciine Chrysomelidae are associated with a variety of aquatic plants, including Nymphaeaceae, Nelumbonaceae, Menyanthaceae and Potamogetonaceae. Adults often feed on pollen, but larvae feed on plant roots beneath the water.); on living vegetation.
Representation in Britain and Ireland, and worldwide. At least 35000 species worldwide; genera about 2500. 254 species in Britain; genera in Britain 52; Calomicrus, Cassida, Cryptocephalus, Donacia, Entomoscelis, Lema, Labiostomis, Lamprosoma, Leptinotarsa, Macroplea, Mantura, Phyllobrotica, Phyllotreta, Prasocuris, Psillioides, Pyrrhalta, Timarcha, etc.
Classification. Suborder Polyphaga; Infraorder Cucujiformia; Superfamily Chrysomeloidea. E.g., Phyllobrotica quadrimaculata (Orange-and-black Galeruca); Mantura matthewsii (Matthews's Haltica); Cassida salicorniae Curtis, = C. vittata: Samphire Tortoise-beetle); Entomoscelis adonidis (Lincolnshire Chrysomela: not indigenous); Lema cyanella (Spencean Crioceris); Cryptocephalus bipunctatus (Yellow-tipped Cryptocephalus); Donacia claviceps, Pyrrhalta viburni (Striped-legged Galeruca); Labiostomis tridentata; Lamprosoma concolor (Knotted-horned Byrrhus); Calomicrus circumfuscus (Striped Galeruca); Phyllotreta ochripes; Prasocuris junci (Blue Helodes); Psilliodes chalcomera (Thigh-spotted Altica); Macroplea appendiculata (Cambridge Macroplea); Leptinotarsa decemlineata (Colorado Beetle); Timarcha tenebricosa (Bloody-nosed Beetle).
General comments. Beetles very variable in form, usually robust, usually not pubescent; tibiae with fewer than two spurs on one or more legs.; metaventrite (= metasternum) without a transverse groove, by contrast with Buprestidae.
Miscellaneous. • Calomicrus circumfusus (Striped Galeruca: B. Ent. 370). • Calomicrus circumfusus: B. Ent. 370, legend+text. • Calomicrus circumfusus: B. Ent. 370, text cont.. • Cassida salicorniae Curtis = C. vittata (Samphire Tortoise-beetle: B. Ent. 127). • Cassida salicorniae Curtis = C. vittata: B. Ent. 127, legend+text. • Cassida salicorniae Curtis = C. vittata: B. Ent. 127, text cont.. • Donacia vulgaris, with dissections from “D. cincta Germ." = D. clavipes?): B. Ent. 494. • Donacia vulgaris: B. Ent. 494, legend+text. • Donacia vulgaris: B. Ent. 494, text cont.. • Prasocuris junci (Blue Helodes: B. Ent. 506). • Prasocuris junci (details, B. Ent. 506). • Prasocuris junci: B. Ent. 506, legend+text. • Prasocuris junci: B. Ent. 506, text cont.. • Donacia, Lema, Macroplea, Plateumaris, Zeugophora: Fowler 4, 127 (1890). CHRYSOMELIDAE. 1, Donacia claviceps; 2, Donacia cinerea. 3, Plateumaris sericea; 4 and 5, Plateumaris sericea vars. 6, Plateumaris discolor; 7, Plateumaris braccata; 8, Plateumaris affinis. 9, Macroplea mutica. 10, Zeugophora subspinosa; 11, Zeugophora flavicollis; 12, Zeugophora turneri. 13, Lema cyanella. From Fowler's plate, with names from the original legend (q.v.) updated. • Galeruca, Galerucella, Longitarsus (5 spp.), Pyrrhalta, Sermylassa: Fowler 4, 134 (1890). CHRYSOMELIDAE. 1, Galerucella tenella; 2, Galerucella sagittariae; 3, Galerucella nymphae. 4, Pyrrhalta viburni. 5, Galeruca tanaceti. 6, Galeruca interrupta, male; 7, Galeruca interrupta, female. 8, Sermylassa halensis. 9, Longitarsus obliteratus; 10, Longitarsus anchusae; 11, Longitarsus absynthii; 12, Longitarsus holsaticus; 13, Longitarsus quadriguttatus. From Fowler's plate, with the names from the original legend (q.v.) updated. • Cassida, Chaetocnema, Crepidodera, Dibolia, Longitarsus (with Tenebrionidae and Abdera: Fowler Suppl. 18, 1913. CHRYSOMELIDAE. 1, Longitarsus plantagomaritimus; 2, Longitarsus plantagomaritimus var. perplexus. 3, Crepidodera impressa. 4, Chaetocnema confusa; 5, Chaetocnema arida; 6, Chaetocnema conducta. 7, Dibolia cynoglossi. 8, Cassida nobilis var. dollmani. TENEBRIONIDAE. 9, Pentaphyllus testaceus. 10, Corticeus linearis. 11, Cteniopus sulphureus var. bicolor. 12, Prionychus melanarius. MELANDRYIDAE. 13, Abdera affinis. From Fowler's plate, with the names from the original legend (q.v.) updated.
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2012 onwards. Insects of Britain and Ireland: water beetles. Version: 14th April 2022. delta-intkey.com’.
