Synonyms
Rhyzobius Stephens, 1829: 239. TS: Nitidula litura Fabricius, 1781.
Rhizobiu Agassiz, 1846: 327 (unjustified emendation).
Lindorus Casey, 1899: 162. TS: Scymnus loropanthae Blaisdell, 1892.
Rhizobiellus Oke, 1951: 21 (replacement name).
Diagnosis
Rhyzobius can be recognized by its long antenna (more than 0.8 times head width); large and coarsely facetted eyes (rarely reduced); mid- and hind tibiae with two apical spurs and the tarsal claws not sexually dimorphic and appendiculate.
Description
Length 1.0-5.2 mm. Body small to medium sized; head dorsally partially covered by pronotum;; dorsum uniformly hairy. Elytral colour brown to blackish, rarely with metallic tint. Eyes coarsely facetted, not or weakly emarginate. Antenna 11-segmented; almost as long as head capsule; antennomere 3 long; antennal club 3-segmented. Terminal maxillary palpomere weakly expanded apically. Prosternum moderately long in front of coxae; prosternal process broad with distinct and complete carinae. Anterior margin of mesoventrite straight medially. Mesoventrite narrower than coxal diameter; Metaventral postcoxal lines recurved. Elytral epipleuron narrow often incomplete apically, not foveate. Mid and hind tibiae with two apical spurs; claws with weak tooth at base or simple. Abdominal postcoxal line recurved and complete. 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; styli strongly reduced and hardly visible; infundibulum absent; sperm duct simple, uniform in diameter. Spermatheca worm-like, without clear ramus or nodulus; spermathecal accessory gland adjacent to sperm duct.
Distribution and Biology
Natural range of this large genus includes Europe, South Africa, New Caledonia, New Guinea, Australia and New Zealand but the generic assignement of many species needs revision. Richards (1981) studied biology and ecology of two species feeding on various scales in the Sydney area. Other species of the genus are found under bark, on branches, flowers or in litter but their detailed biology remains largely unknown.
Genus References
Stephens, J F. 1829. A systematic catalogue of British Insects: being an attempt to arrange all the hitherto discovered indigenous insects in accordance with their natural affinities. Containing also the references to every English writer on entomology, and to the principal foreign authors. With all the published British genera to the present time.Part 1. Baldwin & Cradock, London. xxxiv + 416 pp.
Agassiz, J L R. 1846. Nomenclator zoologicus index universalis. Jent & Grassmann, Soloduri. 393 pp.
Casey, T. L. 1899. A revision of the American Coccinellidae. Journal of the New York Entomological Society, 7, (2): 71-169.
Oke, C G. 1951. The Coleoptera of the Russell Grimwade Expedition. Memoirs of natn Museum Victoria, 17: 19-25.
Pope, R D. 1981. 'Rhyzobius ventralis' (Coleoptera: Coccinellidae), its constituent species, and their taxonomic and historical roles in biological control. Bulletin of Entomological Research, 71: 19-31.
Richards, A M. 1981. Rhyzobius ventralis (Erichson) and R. forestieri (Mulsant) (Coleoptera: Coccinellidae), their biology and value for scale insect control. Bulletin of Entomological Research, 71: 33-46.
Slipinski, S.A. 2007. Australian Ladybird Beetles (Coleoptera: Coccinellidae) their biology and classification. ABRS, Canberra. 286 pp.
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