Elateriformia (Coleoptera)

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J. F. Lawrence, A. M. Hastings, M. J. Dallwitz, T. A. Paine and E. J. Zurcher

SCIRTIDAE (major part)

(= Cyphonidae, Helodidae).

Classification. Polyphaga: Elateriformia.

Distribution. Scirtidae are cosmopolitan in distribution but are far more diverse in the cool temperate parts of the Northern and Southern Hemispheres, and relatively uncommon in tropical climates.

Biogeographic regions: Nearctic, Palearctic, Neotropical, Afrotropical, Oriental, Australian.

Biology. Adult Scirtidae are usually encountered on plant surfaces, but they are relatively short-lived. Larvae are usually aquatic, occurring in still water, such as ponds, lakes or tree holes; a few Southern Hemisphere forms, however, have been copllected in moist, rotten wood well away from water.

References

Armstrong, J. W. T. 1953. On Australian Helodidae (Coleoptera). I. Description of new genera and species. Proceedings of the Linnean Society of New south Wales 78: 19–32.

Beier, M. 1949. Korperbau und Lebensweise der Larve von Helodes hausmanni Gredler (Col. Helodidae). Eos 25: 49–100.

Beier, M. 1952. Structure and function of the mouthparts in helodid larvae (Col.). Transactions of the International Congress of Entomology 9(1): 135–138.

Broun, T. 1880. Manual of the New Zealand Coleoptera. Colonial Museum and Geological Survey Department, Wellington, xix + 651 pp.

Broun, T. 1893. Manual of the New Zealand Coleoptera. Parts V., VI., VII. New Zealand Institute, Wellington, pp. i-xvii, 975–1504.

Hannappel, U. and H. F. Paulus 1987. Arbeiten zu einem phylogenetishcen System der Helodidae (Coleoptera) - Feinstrukturuntersuchungen an europäischen Larven. Zoologische Beiträge (N.F.) 31: 77–150.

Hannappel, U. and H. F. Paulus 1992(1991). Some undetermined Helodidae larvae from Australia and New Zealand: fine structure of mouthparts and phylogenetic position, pp. 89–128. IN: M. Zunino, X. Bellés and M. Blas (eds.), Advances in Coleopterology. Associación Europea de Coleopterología, Barcelona.

Klausnitzer, B. 1974. Anwendung der phylogenetischen Systematik innerhalb von Gattungen dargestellt am Beispiel der Gattung Helodes Latreille, 1796 (Coleoptera, Helodidae). Zoologische Jahrbücher, Abteilung für Systematik, Ökologie und Geographie der Tiere 101: 479–559.

Klausnitzer, B. 1976. Zur Kenntnis der nordamerikanischen Arten der Gattung Cyphon Paykull (Col., Helodidae) (40. Beitrag zur Kenntnis der Helodidae). Polskie Pismo Entomologiczne 46: 439–453.

Klausnitzer, B. 1977. Zur Kenntnis der Helodidae Madagaskars (Coleoptera). Reichenbachia 16: 177–193.

Klausnitzer, B. 1995. Scirtidae, pp. 287–288. IN: M. A. Jäch and L. Ji (eds.), Water Beetles of China. Vol. I. Zoologisch-Botanische Gesellschaft in Österreich und Wiener Coleopterologenverein, Vienna.

Lawrence, J. F., N. B. Nikitsky and A. G. Kirejtshuk 1995. Phylogenetic position of Decliniidae (Coleoptera: Scirtoidea) and comments on the classification of Elateriformia (sensu lato), pp. 375–410. IN: J. Pakaluk and S. A. Slipinski (eds.), Biology, Phylogeny, and Classification of Coleoptera: Papers Celebrating the 80th Birthday of Roy A. Crowson. Muzeum i Instytut Zoologii Polska Akademia Nauk, Warsaw.

Lohse, G. A. 1979. 40. Familie: Helodidae, pp. 250–263. IN: H. Freude, K. W. Harde and G. A. Lohse (eds.), Die Käfer Mitteleuropas. Band 6. Diversicornia. Goecke & Evers, Krefeld.

Nyholm, T. 1969. Über Bau und Funktion der Kopulationsorgane bei den Cyphones (Col. Helodidae). Studien über die Familie Helodidae. X. Entomologisk Tidskrift 90: 233–270, 8 pls.

Nyholm, T. 1971. Beiträge zur Kenntnis der paläarktischen Helodiden. 2. Bemerkungen über die Gattung Prionocyphon Redtb. mit Beschreibung zweier neuer Arten aus dem Mittelmeergebiet. Studien über die Familie Helodidae. XII. Entomologisk Tidskrift 92: 28–42.

Nyholm, T. 1972. Zur Morphologie und Funktion des Helodiden-Aedoeagus (Col.). Entomologica Scandinavica 3: 81–119.

Pic, M. 1914. Pars 58. Dascillidae, Helodidae, Eucinetidae. IN: S. Schenkling (ed.), Coleopterorum Catalogus. W. Junk, Berlin, 65 pp.

Pope, R. D. 1976. Nomenclatural notes on the British Scirtidae (= Helodidae) (Col.). Entomologist's Monthly Magazine 111: 186–187.

Sharp, D. 1878. On the Dascillidae of New Zealand. Annals and Magazine of Natural History (5) 2: 40–59.

Treherne, J. E. 1954. Osmotic regulation in the larvae of Helodes (Coleoptera: Helodidae). Transactions of the Royal Entomlogical Society of London 105: 117–130.

Young, D. K. 2000. 41. Scirtidae. IN: R. H. Arnett, Jr. and M. C. Thomas (eds.), American Beetles. CRC Press, Gainesville, Florida (in press).

General appearance. Total length 1.5–12 mm. Ratio of body length to greatest body width 1.52–2.62. Body strongly flattened, or slightly flattened to moderately convex, or strongly convex. Sides of body not evenly curved, or evenly curved. Body not capable of conglobation (rolling into a ball). Upper surfaces of body glabrous or subglabrous, or clothed with distinct hairs, setae or scales. Vestiture of upper surfaces not including stiff, erect, dark bristles; not including scales or scale-like setae. Upper surfaces of body without deep foveae. Prothorax, metathorax and-or abdomen without extrusible glands. Underside of body without hydrofuge surface(s).

Head. Ratio of head length to its greatest width (excluding eyes) greater than 1, or 1 or less. Head width just behind eyes not distinctly greater than prothoracic width. Head moderately to strongly declined; not entirely concealed from above by pronotum, or entirely concealed from above by pronotum; without elongate rostrum; not abruptly constricted posteriorly. Temples absent or not closely adpressed to prothorax; absent. Transverse occipital ridge or carina absent. Occiput without stridulatory file. Longitudinal axis of head (from occipital foramen to mouth cavity) inclined at an angle of less than 45 degrees. Frontal region not to moderately, gradually declined. Occipital region without median longitudinal groove or line (endocarina). Frontal region without median groove or line (endocarina). Head without ocelli.

Compound eyes present. Eyes not or only slightly protuberant, or strongly protuberant. Vertical diameter of eye less than 2 times horizontal diameter. Eyes finely facetted; without interfacetal setae. Ommatidium of the eucone type, or of the acone type. Eye entire. Anterior or mesal edge of eye not or only barely emarginate. Posterior edge of eye not or barely emarginate.

Antennal insertions exposed from above; moderately to widely separated. Antennae not borne on raised tubercles. Antennal insertions flush with head capsule or raised, not in fossae, or countersunk so that they lie within saucer-like fossae. Subantennal groove or cavity on head absent or very weakly developed, or well developed. Frontoclypeal suture absent or incomplete, or indistinctly impressed; straight, slightly curved or angulate. Clypeus not laterally emarginate. Anterior edge of clypeus or clypeolabrum straight to convex. Mouth cavity anteriorly or anteroventrally oriented. Pregular area without laterally opening cavities. Head ventrally with paired subgenal ridges. Head without anteriorly-projecting genal processes. Gular sutures widely separated or absent. Corporotentorium broad, or narrow; without median process. Cervical sclerites present.

Antennae. Number of antennomeres 11. Antennae when posteriorly extended reaching beyond middle of prothorax but not middle of elytra, or reaching beyond middle of elytra but not elytral apices. Antennae filiform, or serrate, or pectinate or bipectinate. Antennomeres 3, 4 or 5 to 10 without or with single rami (uniramose), or with double rami (biramose) (rare). Antennae at least partly pubescent or with obvious modifications. Antennal modifications beginning on antennomere 3 (rarely 2), or antennomere 4. First antennomere (scape) less than 3 times as long as 2nd (pedicel), or more than 3 times as long as 2nd (pedicel). Antenna not geniculate; without apical club.

Mouthparts. Labrum at least partly visible; free, membranous or separated by suture. Major portion of labrum strongly transverse, or slightly transverse or subquadrate. Apex of labrum subtruncate to slightly convex, or strongly convex, narrowly rounded or acute, or slightly concave or emarginate, or deeply emarginate or bilobed. Labrum moderately to heavily sclerotized, except at base and-or apex. Mouthparts not forming a piercing or sucking tube. Mandibles present. Mandible short and broad, or moderately elongate. Mandibular apex moderately to strongly, gradually curved mesally, or strongly and abruptly curved mesally; unidentate, truncate or rounded; subacute, bidentate or multidentate. Dorsal part of mandible without tubercle; without setose cavity. Mandible moderately to strongly, more or less evenly sclerotized or pigmented; visible in lateral view. Incisor edge of mandible simple, or with single tooth, or with 2 or more teeth. Mandible with well developed mola, or with reduced mola, or without mola; with well developed prostheca, or with reduced prostheca, or without prostheca. Prostheca absent or without articulated, sclerotized process. Inner basal angle of mandible without pubescent process. Maxilla with distinct galea and lacinia. Maxillary lobe(s) not stylet-like. Apex of galea or maxillary lobe densely setose or spinose; without heavily sclerotized teeth or hooks. Lacinia without hook(s) or spine(s). Apical maxillary palpomere cylindrical to fusiform; at least as wide as or longer than preapical one. Maxillary palp without complex palp organ. Apical labial palpomere cylindrical to fusiform. Ligula undivided or finely cleft, or shallowly to moderately emarginate, or deeply emarginate or bilobed.

Prothorax. Ratio of pronotal length to greatest pronotal width 0.25–0.83. Prothorax widest anteriorly, or at middle, or posteriorly. Sides of prothorax more or less straight, or moderately to strongly curved, or straight posteriorly, curved anteriorly. Prothorax not laterally compressed to form cavities for legs. Sides of prothorax not or slightly explanate, or moderately to strongly, horizontally explanate. Base of prothorax not or slightly narrower than elytral bases, or distinctly narrower than elytral bases. Greatest prothoracic width not or slightly narrower than greatest elytral width, or distinctly narrower than greatest elytral width. Lateral pronotal carinae complete; simple; visible for their entire lengths from above; without a raised margin, or with a raised margin or narrow bead. Lateral portion of prothorax without deep pit. Pronotum without anterolateral callosities. Anterior angles of pronotum absent or not produced forward, or distinctly produced forward; absent, right or rounded, not produced, or produced and broadly rounded or obtusely angulate, or produced and narrowly rounded or acute. Posterior angles of pronotum absent or broadly rounded, or obtuse or right, or moderately to strongly acute; not produced and acute. Posterior edge of pronotum more or less straight or evenly rounded; simple; not or vaguely margined, or with narrow raised margin or bead. Discal carinae of pronotum absent. Pronotal disc without paired basal impressions, or with paired basal impressions. Pronotum without median longitudinal groove or line. Anterior edge of pronotum simple, without margin, or with narrow margin or bead. Hypomeron without pit.

Anterior portion of prosternum at midline shorter than prosternal process. Lateral portion of prosternum in front of coxae shorter than mid length of procoxal cavity. Anterior edge of prosternum not produced anteriorly. Prosternum in front of coxae flat to moderately convex. Prosternum in front of coxae without paired lines or carinae. Anterior edge of prosternum without margin; without mesal excavation. Anterolateral or ventrolateral portions of prothorax without cavities or grooves. Prothoracic cavities absent. Prothoracic grooves absent. Prosternal process complete; parallel-sided, or gradually expanded or narrowed and then expanded; slightly to strongly elevated but not curved behind; slightly overlapping mesoventrite, or moderately to strongly overlapping mesoventrite. Apex of prosternal process acute or narrowly rounded. Prosternal process without transverse groove. Accessory (mesal) procoxal articulation absent. Ventral portion of prothorax on each side with notosternal suture only. Propleuron not extending to anterior edge of prothorax. Propleuron or pleurotrochantin not extending behind coxa. Procoxae not or slightly projecting below prosternum. Procoxa without or with short concealed lateral extension. Procoxal cavity strongly transverse. Procoxal cavities at middle narrowly separated. Procoxal cavities externally open; broadly open. Postcoxal projection absent or very short. Procoxal cavities without narrow lateral extensions. Procoxal cavities internally open. Prothoracic trochantin or pleurotrochantin at least partly exposed. Promesothoracic clicking mechanism absent.

Elytra. Elytra present. Ratio of elytral length to greatest elytral width 1.22–2.1. Ratio of elytral length to pronotal length 3.14–7.42. Elytra apunctate, irregularly punctate, or with 5 or fewer distinct puncture rows or striae; without scutellary striole. Sutural stria absent or not deeply impressed near apex. Abdominal tergites exposed by elytra none or apex of 1. Elytral apices meeting or almost meeting at the suture. Elytral suture not deflected near apex. Elytral apex without internal interlocking tongue. Epipleuron complete; not or gradually narrowed. Lateral edge of elytron straight or weakly sinuate.

Pterothorax. Scutellum well developed; not abruptly elevated, or abruptly elevated; anteriorly simple; posteriorly narrowly rounded or acute. Mesoscutum without stridulatory file. Mesoventrite with paired procoxal rests. Paired mesoventral procoxal rests absent, horizontal or slightly oblique, or moderately to strongly oblique, or vertical. Anterior edge of mesoventrite without prosternal rest. Mesoventrite not divided by longitudinal groove or discrimen. Anterior edge of mesoventrite at midline on same plane as metaventrite, or on different plane than metaventrite. Mesoventral cavity small and shallow, or moderately large and shallow. Mesocoxa not conical and projecting. Mesocoxal cavities at middle narrowly separated. Mesocoxae separated by less than shortest diameter of coxal cavity. Mesocoxal cavities circular to slightly transverse; not or slightly oblique. Mesoventrite separated by complete sutures from mesepisterna. Mesepisterna distinctly separated at midline; without deep pockets. Mesepimeron not visible from above. Mesocoxal cavities open laterally; not partly closed by metepisterna, or partly closed by metepisterna (barely). Mesoventral process extending at least to middle of mesocoxal cavity. Mesometaventral junction a complex fitting. Mesoventral and metaventral processes at midline separated by gap, groove, or suture. Accessory (mesal) mesocoxal articulation absent.

Metaventral discrimen or median line moderately to very long. Paired postcoxal lines of metaventrite absent, or present. Postcoxal lines of metaventrite absent, or arched but not or slightly recurved. Metaventrite longer than first abdominal ventrite. Postcoxal pits of metaventrite absent. Metaventrite flat to slightly convex. Transverse groove of metaventrite absent, or present. Anterior edge of metaventrite without transverse carina between mesocoxal cavities. Exposed portion of metepisternum short and broad, or moderately elongate. Metacoxae contiguous or narrowly separated; separated by less than longest coxal diameter; extending laterally to meet elytra or sides of body; completely separated from metaventrite by suture. Metacoxal plates well developed mesally, weak laterally, or weakly developed; not concealing most of basal abdominal ventrite. Metacoxae not greatly enlarged; horizontally oriented. Lateral arms of metendosternite short or absent, or moderately to very long. Metendosternal laminae absent. Ventrolateral processes of metendosternite strongly developed. Anterior process of metendosternite moderately long. Anterior tendons of metendosternite moderately or very close together, or widely separated but not on lateral arms. Apical portion of metendosternite not or only slightly emarginate.

Hind wing. Hind wing well developed; with normal transverse folds. Radial cell of hind wing well developed; shorter and broader. Inner posterior angle formed at base of radial cell right or obtuse. Radial cell forming equilateral triangle. Ratio of length of apical area to total wing length 0.20–0.35. Apical area of hind wing without veins or sclerotizations, or with one or more vague sclerotizations or pigment patches. Medial bar of hind wing not crossed by fold. Free veins in medial area of hind wing 3 or fewer. Oblongum cell of hind wing absent. Medial fleck of hind wing absent; absent or not partly bisected by a vein. Wedge cell of hind wing absent. Anal lobe of hind wing present. Posterior edge of hind wing without fringe of long hairs.

Legs. Femoral attachment of mid trochanter strongly oblique with base of femur separate from coxa. Mesotrochanter not reduced or concealed from below. Metafemur not much wider than mesofemur. Mesotibia not strongly widened. Outer edge of mesotibia simple, crenulate or denticulate, or with distinct teeth or long spines. Outer subapical edge of mesotibia without antenna cleaner. Preapical surfaces of mesotibia without ridges or combs. Outer apical angle of mesotibia simple or slightly produced, without lobe, teeth or spines. Inner apical angle of mesotibia not or slightly produced, without tooth. Mesotibial spurs glabrous or absent; double. Mesotarsus with 5 distinct tarsomeres (pentamerous). Tarsomeres on hind leg at least as many as on mid leg. Tarsomeres on fore leg at least as many as on mid leg. Mesotarsomere 1 well developed and visible. Preapical mesotarsomeres together longer than apical one. Penultimate mesotarsomere not distinctly shorter than antepenultimate. Ventral mesotarsal lobes on penultimate tarsomere only. Mesotarsal claws paired; subequal in length and similar in form and angle of inclination; simple. Appendage on each tarsal claw absent. Mesotarsal claws without setae near base. Mesotarsal empodium absent or concealed; absent or with 2 or fewer setae. Outer edge of protibia simple and rounded to carinate but without lobes or teeth, except at apex. Outer apical angle of protibia simple or slightly produced, without lobe, teeth or spines. Inner subapical edge of protibia without antenna cleaner. Protibial spurs double. Articulations of protibial spurs located in same plane. Hind legs without swimming hairs. Preapical surfaces of metatibia without ridges or combs. Metatibial articular area not to only moderately expanded, narrowly oval or oblique. Metatibial spurs double; subequal in length and form, or differing distinctly in length.

Abdomen. Number of abdominal ventrites 5. Number of basal ventrites connate two. Abdominal sternite 2 apparently absent. First ventrite not completely divided by metacoxae. Suture between ventrites 1 and 2 distinct. Suture between ventrites 2 and 3 distinct. Ventrite 4 articulated with or connate with both 3 and 5. Postcoxal lines on ventrite 1 absent. Ventrite 1 not much longer than 2. Abdominal process acute or narrowly rounded. Ventrite 5 in female without circular depression. Posterior edge of ventrite 5 not crenulate. Last visible tergite and-or sternite (7 or 8) not forming terminal spine. Tergite and sternite 7 separated by membrane or distinct suture. Subapical abdominal luminous organ absent. Ventrites without setose patches or foveae. Functional spiracles on abdominal segment 8 absent. Functional spiracles on abdominal segment 7 present. Functional spiracles on abdominal segment 6 present. Functional spiracles on abdominal segment 5 present. 7th abdominal spiracles located in pleural membrane. 6th abdominal spiracles located in pleural membrane. 5th abdominal spiracles located in pleural membrane. Anterior edge of sternite 8 in male without median strut. Pygidium (sclerotized tergite 7 or 8) more or less horizontal. Anterior edge of sternite 9 in male without median strut. Tergite 9 in male completely fused to tergite 10. Tergite 10 in male completely membranous or fused to tergite 9.

Aedeagus unclassified; symmetrical, or asymmetrical. Anterior edge of tegmen or phallobase without struts. Parameres fused to phallobase or base of penis but free from one another, or partly or entirely fused together and to phallobase, or absent (?); not outwardly hooked. Penis without dorsal and ventral lobes, or with dorsal and ventral lobes. Anterior edge of penis without struts.

Illustrations. • Cyphon. Cyphon pubescens (Fabricius). Locality: Denmark. Artist: Victor Hansen. Courtesy of Danmarks Fauna and Zoological Museum, University of Copenhagen. Reference: Hansen 1973.


The interactive key provides access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting specified attributes, and summaries of attributes within groups of taxa.

Cite this publication as: ‘Lawrence, J.F., Hastings, A.M., Dallwitz, M.J., Paine, T.A., and Zurcher, E.J. 2000 onwards. Elateriformia (Coleoptera): descriptions, illustrations, identification, and information retrieval for families and subfamilies. Version: 9th October 2005. http://delta-intkey.com’.

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