Orcus (Halmus) Mulsant, 1850: 471. TS: Coccinella chalybea Boisduval, 1835.
The species of this genus closely resemble those of the genus Orcus in general body shape and metallic colour; however, they can be distinguished easily by the 7-segmented antenna, non-emarginate eyes, narrowly margined pronotal base and always unicoloured elytra.
Length 2.5-4.5 mm. Dorsum glabrous; elytra black to green, sometimes with metallic sheen, without markings. Head transverse; eye not emarginate. Antenna 7-segmented, short; scape asymmetrical; terminal antennomere as long as to distinctly shorter than penultimate one. Clypeus short, usually emarginate medially and extending laterally below eyes; labrum partially exposed. Maxillary palp moderately long, last palpomere somewhat expanded apically to securiform. Pronotal base entirely bordered, marginal bead very close to posterior edge; prosternal process narrow, without carinae; hypomeral fovea absent. All tibiae simple externally, without apical spurs; claw strongly appendiculate. Elytral margin weakly reflexed with reduced bead; epipleuron broad, strongly descending without foveae. Abdomen with 6th ventrite visible in both sexes; postcoxal lines separated at middle, each running parallel to posterior margin of ventrite or recurving apicall. Male terminalia. Parameres and phallobase symmetrical; penis guide symmetrical. Parameres articulated with phallobase. Penis stout, consisting of single sclerite; basal capsule distinct and T-shaped. Apodeme of male sternum 9 very narrow and rod-like. Female terminalia. Coxities triangular, about as long as broad, or broad plates; styli terminal, well developed, with apical setae; infundibulum horn-like, with sperm duct originating at its base; sperm duct divided into two regions of different diameter. Spermatheca globular without clear cornu; spermathecal accessory gland adjacent to sperm duct.
Distribution and Biology
Six known species occur along northern and eastern coasts of Australia, with one species also occurring in New Guinea. H. chalybeus has been introduced to California, Hawaii and New Zealand as a biological control agent of various scale insects..
Chapin, E. A. 1965. The genera of the Chilocorini (Coleoptera, Coccinellidae). Bulletin of the Museum of Comparative Zoology, 133(4): 227-271.
Mulsant, M E. 1850. Species des Coléoptères Trimcres Sécuripalpes. Annales des Sciencies Physiques et Naturelles, d'Agriculture et d'Industrie, publiées par la Société nationale d'Agriculture, etc., de Lyon, Deuxicme Série, 2: xv + 1-1104 (part 1 pp. 1-450; part 2 pp. 451-1104).
Slipinski, S.A. 2007. Australian Ladybird Beetles (Coleoptera: Coccinellidae) their biology and classification. ABRS, Canberra. 286 pp.
Slipinski, A, and J. A Giorgi. 2006. Revision of the Australian Coccinellidae (Coccinellidae). Part 6. Tribe Chilocorini. Annales Zoologici (Warszawa), 56, (2): 265-304.
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