Elateriformia (Coleoptera) Larvae

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

CHELONARIIDAE

Polyphaga: Elateriformia.

Chelonarium is common in the tropical and subtropical parts of the New World and eastern Asia to northern Australia, while Pseudochelonarium is restricted to Southeast Asia and the East Indes.

Larvae of Chelonariidae have been collected in the root systems of orchids and other epiphytes, in leaf litter and forest debris, under bark and in the refuse heaps of leaf-cutting ants; they apparently feed on decaying plant matter.

References

Böving, A. G. and Craighead, F. C. (1931). An illustrated synopsis of the principal larval forms of the order Coleoptera. Entomologica Americana (New Series) 1: 1–351, 125 pls.

Costa, C., Vanin, S. A. and Casari-Chen, S. A. (1988). Larvas de Coleoptera do Brasil, vi + 282 pp. Museu de Zoologia, Universidade de Sao Paulo: Sao Paulo.

Spangler, P. J. (1991). Chelonariidae (Dryopoidea), pp 394–395 in Stehr, F. W. (ed.), Immature Insects. Vol. II. Kendall Hunt: Dubuque, Iowa.

Body. Length less than 3 mm, or 3 to 15 mm. Body not broadly ovate and strongly flattened; relatively straight or only slightly curved ventrally; circular in cross-section, or slightly flattened; body, as viewed from above elongate and more or less parallel-sided, or oblong to ovate, not parallel-sided. Vestiture including bristles, scales, expanded or complex hairs. Dorsal surfaces more or less heavily pigmented or sclerotized; generally granulate or tuberculate. Ventral surfaces more or less heavily pigmented.

Head. Head prognathous or slightly declined; protracted or slightly retracted; not concealed from above by prothorax; narrower than thorax; not forming sclerotized, serrate, wedge-like plate. Head capsule not strongly depressed and wedge-like anteriorly; posterior edge of head capsule not or only slightly emarginate. Median epicranial region without longitudinal furrow. Epicranial stem moderately long; straight, not bent to the left. Frontal arms present; V-shaped or U-shaped; not joined anteriorly by transverse line; bases of frontal arms contiguous. Median endocarina absent or coincident with epicranial stem. Paired endocarinae absent or coincident with frontal arms. Number of stemmata one. Number of antennal segments three. Ratio of antennal length to head width less than 0.15. Sensorium(a) on preapical antennal segment present; shorter than apical segment. Sensorium(a) on preapical (or apical) antennal segment conical or palpiform. Apex of preapical antennal segment truncate, so that sensorium and apical segment arise together. Antennal base without eversible membranous lobe. Frontoclypeal suture distinct. Labrum separated from head capsule by complete suture. Epipharyngeal rods absent. Mouthparts not forming sucking tube. Mandibles symmetrical; opposable, at least slightly curving mesally at apex; not approximate, diverging and longitudinally divided; broad and stout or more or less wedge-like; without groove or perforation. Apex of mandible broad when viewed from in front (perpendicular to plane of movement); trilobed or tridentate. Accessory ventral process of mandible absent. Incisor edge of mandible with 1 or 2 subapical teeth. Mesal surface of mandibular base simple or slightly expanded. Mandibular mola absent. Ventral mouthparts retracted. Cardo distinct and sclerotized; undivided; transverse to slightly oblique. Cardines or maxillary bases completely fused or combined with labium to form single plate. Stipes longer than wide. Maxillary articulating area absent. Maxilla with single, articulated mala. Mala or galea 2-segmented. Apex of mala simple, not cleft; or galea rounded or truncate; or galea bearing simple seta or spine. Inner apical angle of mala simple. Number of segments in maxillary palp four. First segment of maxillary palp without digitiform appendage. Labium consisting of prementum and postmentum. Mentum, postmentum or labial plate partly or completely fused with maxillae (sutures incomplete or absent). Postmentum or labial plate subquadrate or trapezoidal, with blunt posterior edge. Postmentum or labial plate not divided longitudinally. Ligula shorter than labial palp. Ligula simple, not bilobed; without tooth-like sclerome. Number of segments in labial palp two. Labial palps separated by more than width of first palp segment. Hypopharyngeal bracon present. Hypopharyngeal sclerome absent. Hypostomal region present (separating labium from thorax). Hypostomal rods absent. Ventral epicranial ridges present. Gula longer than wide; gular sutures separate. Gula or gular region separated from labium by suture. Occipital foramen not divided by tentorial bridge.

Thorax. Prothorax not or only slightly wider than abdomen; not longer than meso- and metathorax combined. Thoracic terga without patches of asperities; without rows of asperities or carinae. Protergum with 1 or more sclerotized plates. Meso- and metaterga with 1 or more sclerotized plates. Thorax without well-developed lateral tergal processes, or with well-developed lateral tergal processes. Prosternum without armature. Mesocoxae or coxal lobes separated by less than 1 basal coxal diameter, or separated by 1 to 2 basal coxal diameters. Thoracic legs articulated. Number of segments in mesothoracic leg five including pretarsus (claw). Number of segments in mesothoracic leg five or fewer including pretarsus (claw). Legs not highly reduced, more than 0.2 times as long as head width. Metathoracic leg about same size as mesothoracic leg. Meso- and metathoracic legs not forming stridulatory organ. Apical segment of leg acute and claw-like (or consisting of 2 claws). Number of movable pretarsal claws one. Number of setae on pretarsus one. Thoracic spiracles undulate; not placed at ends of spiracular tubes.

Abdomen. Ratio of length of abdomen (without appendages) to length of thorax more than 2.0. Number of visible abdominal segments ten. Abdominal terga not extending laterally beyond edges of sterna; without patches of asperities; without rows of asperities. Abdomen without well-developed lateral processes, or with 1 pair of lateral processes on most segments. Abdominal tergum 3 without transverse dorsal folds or lobes; simple, not divided into transverse dorsal folds or lobes. Paired abdominal glands (openings or porous plates) absent. Dorsal, balloon-like tracheal gills absent. Long and narrow, lateral gills absent. Abdominal sterna without patches of asperities; without rows of asperities. Paired ventral prolegs (or asperity-bearing ampullae) absent. Ventral abdominal gill tufts absent. Abdominal tergum 8 without special armature. Abdominal apex without respiratory chamber. Abdominal segment 9 excluding appendages as long as or slightly longer than segment 8. Abdominal tergum 9 not forming articulated plate; extending onto ventral surface; without paired processes or urogomphi, or with paired processes or urogomphi; without pit between urogomphi; without median process or terminal disc. Ratio of length of urogomphus to basal width of tergum 9 less than 0.2, or between 0.2 and 1.0. Urogomphi fixed at base; unsegmented; not bifurcate and without accessory processes; posteriorly oriented; separated by less than 1 basal width, or between 1 and 2 basal widths. Abdominal sternum 9 partly or entirely exposed; simple or apparently absent; not enclosed by sternum 8. Abdominal apex with ventrally hinged operculum. Abdominal segment 10 without oval lobes separated by longitudinal groove; concealed from above, sometimes membranous or more or less fused to segment 9; without asperated, tubular holdfast organs. Paired pygopods on segment 10 absent. Anal region posteriorly or terminally oriented. Anal gill tufts absent. Anal hooks absent. Anterior abdominal spiracles undulate. Abdominal spiracles all placed at ends of lateral spiracular tubes. Spiracular tubes or processes on abdominal segment 3 shorter than wide. Eighth abdominal spiracles functional and about the same size as others on abdomen; abdominal spiracle 8 lateral or dorsolateral, facing laterally.

Illustrations. • Chelonarium.


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. 1995 onwards. Elateriformia (Coleoptera) larvae: descriptions, illustrations, identification, and information retrieval for families and subfamilies. Version: 9th October 2005. http://delta-intkey.com’.

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