Elateriformia (Coleoptera) Larvae

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

OMALISIDAE

(= Homalisidae or Omalysidae).

Polyphaga: Elateriformia.

Omalisidae occur in Europe and Asia Minor.

Larvae of Omalisus fontisbellaquei Fourcrouy occur in leaf litter and feed on millipedes of the genus Glomeris.

References

Burakowski, B. (1988). Observations on the larval morphology and biology of Omalisus fontisbellaquei Fourcroy (Coleoptera: Homalisidae). Polskie Pismo Entomologiczne 58: 571–574.

Lawrence, J. F. (1991). Homalisidae (Cantharoidea), pp 422–423 in Stehr, F. W. (ed.), Immature Insects. Vol. II. Kendall Hunt: Dubuque, Iowa.

Body. Length less than 3 mm to more than 15 mm. Body not broadly ovate and strongly flattened; relatively straight or only slightly curved ventrally; strongly flattened; body, as viewed from above elongate and more or less parallel-sided. Vestiture consisting of fine hairs or setae only. Dorsal surfaces more or less heavily pigmented or sclerotized; generally smooth. Ventral surfaces very lightly 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 absent or very short. Frontal arms absent. 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 more than 0.50. Sensorium(a) on preapical antennal segment as long as or longer than apical segment. Apex of preapical antennal segment truncate, so that sensorium and apical segment arise together. Antennal base without eversible membranous lobe. Frontoclypeal suture absent or vaguely indicated. Labrum completely fused to head capsule (suture absent); without crenulate emargination. Epipharyngeal rods absent. Mouthparts not forming sucking tube. Mandibles symmetrical; opposable, at least slightly curving mesally at apex; not approximate, diverging and longitudinally divided; narrow and falcate; with open or partly closed groove. Apex of mandible narrow when viewed from in front (parallel or oblique to plane of movement); with single lobe or tooth. 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 strongly protracted. Cardines or maxillary bases separated from each other by labium. Stipes longer than wide. Maxillary articulating area absent. Maxilla with single, articulated mala. Mala or galea consisting of a single segment. Apex of mala simple, not cleft; or galea rounded or truncate; or galea setose or spinose. Inner apical angle of mala simple. Number of segments in maxillary palp three. First segment of maxillary palp without digitiform appendage. Labium consisting of prementum and postmentum. Mentum, postmentum or labial plate completely or almost completely connate with maxillae. Postmentum or labial plate subquadrate or trapezoidal, with blunt posterior edge. Postmentum or labial plate not divided longitudinally. Ligula absent. 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 absent. Gula wider than long. 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. Prosternum without armature. 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 two. Pretarsal setae lying side by side or obliquely situated. Thoracic spiracles biforous or bilabiate; 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. 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 shorter than segment 8. Abdominal tergum 9 not forming articulated plate; extending onto ventral surface; without paired processes or urogomphi; without median process or terminal disc. Abdominal sternum 9 partly or entirely exposed; simple or apparently absent; not enclosed by sternum 8. Abdominal apex without 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 ventrally oriented. Anal gill tufts absent. Anal hooks absent. Anterior abdominal spiracles biforous or bilabiate. Abdominal spiracles not placed at ends of spiracular tubes. Eighth abdominal spiracles functional and about the same size as others on abdomen; abdominal spiracle 8 lateral or dorsolateral, facing laterally.


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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