Elateriformia (Coleoptera)

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

CLAMBIDAE

(Including Calyptomeridae).

Classification. Polyphaga: Elateriformia.

Distribution. Clambinae are widely distributed in both temperate and tropical regions. Species of Acalyptomerus have been seen from Central America, eastern and southern Africa, Mauritius, Japan, India, Sri Lanka, southeast Asia and Australia. Calyptomerus species are native to the temperate parts of the Holarctic region, but the Palaearctic C. dubius (Marsham) has been introduced into South Africa and Tasmania.

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

Biology. Acalyptomerus larvae and adults have been collected in leaf litter, hay stacks and other accumulations of organic debris. Adults have also been collected in bracket fungi. Calyptomerus dubius (Marsham) occurs in haystacks and feeds on molds. Clambines are mycetophagus and some have been associated with Myxomycetes.

References

Crowson, R. A. 1979. Observations on Clambidae (Coleoptera), with descriptions of a new genus and species and of several larvae. Revue Suisse de Zoologie 86: 611–623.

Crowson, R. A. and E. A. Crowson 1955. Some observations on beetles of the family Clambidae. The Glasgow Naturalist 17: 205–206.

Endrödy-Younga, S. 1971. 17. Familie: Clamidae, pp. 266–270. IN: H. Freude, K. W. Harde and G. A. Lohse (eds.), Die Käfer Mitteleuropas. Band 3. Adephaga 2, Palpicornia, Histeroidea, Staphylinoidea 1. Goecke & Evers, Krefeld.

Endrödy-Younga, S. 1981. The American species of the familia Clambidae (Coleoptera: Eucinetoidea). Entomologia Generalis 7: 33–67.

Endrödy-Younga, S. 1990. A revision of the Australian Clambidae (Coleoptera: Eucinetoidea). Invertebrate Taxonomy 4: 247–280.

Endrödy-Younga, S. 1995. Description of two new species of Sphaerothorax Endrödy-Younga (Coleoptera: Clambidae) from Chile: relicts in Nothofagus forests reflecting ecological zonation in Gondwanaland. Annals of the Transvaal Museum 36: 177–182.

Endrödy-Younga, S. 1995. Clambidae of Sulawesi with reference to the biogeograpohy of the Sunda Islands (Coleoptera: Eucinetoidea). Systematic Entomology 20: 1–16.

Endrödy-Younga, S. 1998. The genus Clambus in Central and South America. Annals of the Transvaal Museum 36: 373–403.

Endrödy-Younga, S. 1998. Acalyptomerus Crowson: the circumtropical genus of the family Clambidae (Coleoptera: Clambidae). Koleopterologische Rundschau 68: 199–203.

Hatch, M. H. 1929. Pars 105. Leiodidae, Clambidae. IN: S. Schenkling (ed.), Coleopterorum Catalogus. W. Junk, Berlin, 100 pp.

Young, D. K. 2000. 40. Clambidae. IN: R. H. Arnett, Jr., Jr. and M. C. Thomas (eds.), American Beetles. CRC Press, Gainesville, Florida (in press).

General appearance. Total length 0.7–1.75 mm. Ratio of body length to greatest body width 1.1–1.55. Body 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), or 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) 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, or abruptly constricted posteriorly to form neck. Temples absent or not closely adpressed to prothorax, or closely adpressed to and abutting prothorax; absent, or shorter than length of eye, or longer than length of eye. Transverse occipital ridge or carina present. 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, or absent. Eyes not or only slightly protuberant, or strongly protuberant. Vertical diameter of eye less than 2 times horizontal diameter. Eyes coarsely facetted; without interfacetal setae. Ommatidium of the acone type. Eye entire, or divided into upper and lower parts by moderately to very wide strip of cuticle. Anterior or mesal edge of eye not or only barely emarginate, or shallowly emarginate or slightly divided by canthus, or deeply emarginate or strongly divided by canthus. Posterior edge of eye not or barely emarginate.

Antennal insertions exposed from above, or concealed from above; moderately to widely separated. Antennae not borne on raised tubercles. Subantennal groove or cavity on head well developed. Frontoclypeal suture absent or incomplete, or distinctly impressed; straight, slightly curved or angulate. Clypeus not laterally emarginate. Anterior edge of clypeus or clypeolabrum straight to convex, or concave to shallowly emarginate. 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 narrow; without median process. Cervical sclerites present.

Antennae. Number of antennomeres 8–9, or 10. Antennae when posteriorly extended reaching beyond middle of prothorax but not middle of elytra. Antennae capitate. Antennomeres 3, 4 or 5 to 10 without or with single rami (uniramose). Antennae at least partly pubescent or with obvious modifications. Antennal modifications beginning on antennomere 5 or beyond. First antennomere (scape) less than 3 times as long as 2nd (pedicel). Antenna not geniculate; with strong apical club. Antennal club 2-segmented; not 5-segmented or with 2nd segment subequal to or larger than 1st; loose, or compact; not lamellate; not or slightly serrate; not or slightly flattened; not preceded by a cupule.

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. 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. Mandibular apex moderately to strongly, gradually curved mesally, or strongly and abruptly curved mesally; unidentate, truncate or rounded, or bidentate or bilobed. Dorsal part of mandible without tubercle; without setose cavity. Incisor edge of mandible with 2 or more teeth. Mandible with well developed mola; with well developed prostheca. Prostheca including articulated, sclerotized process. Maxilla with distinct galea and lacinia. Maxillary lobe(s) not stylet-like. Apex of galea or maxillary lobe without or with few setae or spines; without heavily sclerotized teeth or hooks. Lacinia with apical or subapical 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.

Prothorax. Ratio of pronotal length to greatest pronotal width 0.3–0.5. Prothorax widest posteriorly. Sides of prothorax more or less straight, or moderately to strongly curved. Prothorax not laterally compressed to form cavities for legs. Sides of prothorax not or slightly explanate, or moderately to strongly, horizontally explanate, or moderately to strongly, obliquely or vertically explanate. Base of prothorax not or slightly narrower than elytral bases. Greatest prothoracic width not or slightly narrower than greatest elytral width. Lateral pronotal carinae complete; simple, or coarsely dentate; visible for their entire lengths from above; without a raised margin. 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. 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, or moderately to strongly produced forming mesal lobe, or distinctly sinuate or variously lobed; simple; not or vaguely margined. Discal carinae of pronotum absent. Pronotal disc without paired basal impressions. Pronotum without median longitudinal groove or line. 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 mesal excavation. Anterolateral or ventrolateral portions of prothorax without cavities or grooves. Prothoracic cavities absent. Prothoracic grooves absent. Prosternal process complete, or incomplete, or absent; narrowed apically; flat, concave, or only slightly elevated or curved behind coxae; not extending to 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, or without sutures or with incomplete notosternal suture. Propleuron not extending to anterior edge of prothorax. Propleuron or pleurotrochantin not extending behind coxa. Procoxae projecting well below prosternum. Procoxa without or with short concealed lateral extension. Procoxal cavities present, procoxae countersunk. Procoxal cavity strongly transverse, or slightly transverse. Procoxal cavities at middle contiguous. Procoxal cavities externally open; broadly open. Postcoxal projection absent or very short. Procoxal cavities without narrow lateral extensions. Procoxal cavities internally open, or closed by slender bar, or broadly closed. Prothoracic trochantin or pleurotrochantin at least partly exposed. Promesothoracic clicking mechanism absent.

Elytra. Elytra present. Ratio of elytral length to greatest elytral width 0.85–1.2. Ratio of elytral length to pronotal length 0.85–3.6. Elytra apunctate, irregularly punctate, or with 5 or fewer distinct puncture rows or striae, or with more than 5 distinct puncture rows; without scutellary striole. Number elytral puncture rows or striae 12 or more. 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 absent or incomplete; not or gradually narrowed, or abruptly narrowed or excavated. Lateral edge of elytron straight or weakly sinuate.

Pterothorax. Scutellum well developed, or highly reduced, or absent or not visible; abruptly elevated; anteriorly simple; posteriorly narrowly rounded or acute. Mesoscutum without stridulatory file. Mesoventrite without paired procoxal rests, or with paired procoxal rests. Paired mesoventral procoxal rests absent, horizontal or slightly oblique, or moderately to strongly oblique. Anterior edge of mesoventrite without prosternal rest. Mesoventrite not divided by longitudinal groove or discrimen. Anterior edge of mesoventrite at midline on different plane than metaventrite. Mesoventral cavity absent. Mesocoxa not conical and projecting, or conical and projecting. Mesocoxal cavities present, mesocoxae countersunk. Mesocoxal cavities at middle contiguous, or narrowly separated. Mesocoxae separated by less than shortest diameter of coxal cavity. Mesocoxal cavities circular to slightly transverse, or strongly transverse; not or slightly oblique, or moderately to strongly oblique. Mesoventrite separated by complete sutures from mesepisterna, or partly or completely fused to 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. Mesoventral process absent or not extending to middle of mesocoxal cavity, or extending at least to middle of mesocoxal cavity. Mesometaventral junction absent or a point, or a straight line, or a complex fitting. Mesoventral and metaventral processes at midline separated by gap, groove, or suture.

Metaventral discrimen or median line absent. Paired postcoxal lines of metaventrite absent, or present. Postcoxal lines of metaventrite absent. Metaventrite longer than first abdominal ventrite. Postcoxal pits of metaventrite absent. Metaventrite flat to slightly convex, or moderately to strongly convex. Transverse groove of metaventrite absent. Anterior edge of metaventrite without transverse carina between mesocoxal cavities, or with transverse ridge or carina joining posterior edges of mesocoxal cavities. Exposed portion of metepisternum short and broad, or very long and narrow or absent. Metacoxae contiguous or narrowly separated, or widely separated; extending laterally to meet elytra or sides of body; completely separated from metaventrite by suture. Metacoxal plates well developed, more or less uniform; concealing most of first abdominal ventrite. Metacoxae not greatly enlarged, or greatly enlarged; horizontally oriented. Lateral arms of metendosternite moderately to very long. Metendosternal laminae absent. Ventrolateral processes of metendosternite absent or weakly developed, or strongly developed. Anterior process of metendosternite short or absent. Anterior tendons of metendosternite on lateral arms or not apparent. 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, or highly reduced or absent; shorter and broader, or incomplete or absent. 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 greater than 0.5. 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 absent, or present. Posterior edge of hind wing without fringe of long hairs, or with 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. 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. Mesotibial spurs glabrous or absent. Mesotarsus with 4 distinct tarsomeres (tetramerous), or with 3 distinct tarsomeres (trimerous). 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 absent. 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 with 2 or fewer setae. Inner subapical edge of protibia without antenna cleaner. Hind legs without swimming hairs. Preapical surfaces of metatibia without ridges or combs.

Abdomen. Number of abdominal ventrites 5–6. Number of basal ventrites connate none. 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, or 1 pair, strongly curved or recurved. Ventrite 1 not much longer than 2. Abdominal process acute or narrowly rounded, or truncate or slightly emarginate. 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. Subapical abdominal luminous organ absent. Ventrites without setose patches or foveae. Functional spiracles on abdominal segment 8 present, or absent. Anterior edge of sternite 8 in male without median strut. Anterior edge of sternite 9 in male without median strut, or with median strut (spiculum gastrale). Tergite 9 in male slightly to moderately emarginate, or deeply emarginate, or almost completely divided into two parts. Tergite 10 in male well developed and free.

Aedeagus trilobate; symmetrical, or asymmetrical. Anterior edge of tegmen or phallobase without struts. Parameres individually articulated to phallobase or base of penis, or fused to phallobase or base of penis but free from one another, or partly or entirely fused together but articulated to phallobase; not outwardly hooked. Penis without dorsal and ventral lobes. Anterior edge of penis without struts.

Illustrations. • Acalyptomerus. Acalyptomerus sp. Locality: Panama. Artist: S. P. Kim. Copyright CSIRO. • Calyptomerus. Calyptomerus dubius (Marsham). Locality: Europe. Reference: Reitter 1909. • Clambus. Clambus domesticus Broun. Locality: New Zealand. Artist: D. Helmore. Courtesy of Landcare Research New Zealand Ltd. Reference: Kuschel 1990.


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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