Rhyzobius (Rodatus) Mulsant, 1850: 1003. TS: Rhyzobius (Rodatus) bajulus Mulsant, 1850
Rodatus was originally described as a subgenus within Rhyzobius and both these genera are quite similar externally with Rodatus species being generally larger and distinctly flattened as compared to very diverse Australian Rhyzobius. Rodatus can also be distinguished from Australian Rhyzobius by setose foveae on fifth abdominal ventrite in male, much longer antennae with larger scape and strongly asymmetric club, and distinctly securiform maxillary palps.
Length 3.0-7.0 mm. Body medium sized to large; head dorsally largely covered by pronotum; body broadly oval and weakly convex to flat; dorsum uniformly hairy. Elytral colour blackish or brown, rarely with darker irregular markings. Head narrow, elongate with coarsely facetted eyes narrowly separated on vertex. Antenna 11-segmented; slightly shorter than head capsule with scape slightly enlarged and externally arcuate; antennal club 3-segmented, asymmetrical. Terminal maxillary palpomere strongly securiform. Pronotal disc evenly convex; anterior margin weakly arcuate medially. Prosternum long in front of coxae, arcuate; prosternal process moderately broad with complete carinae. Elytral epipleuron narrow, incomplete apically, not foveate. Protibia not angulated externally. Tibial spurs formula 0-2-2. Abdominal postcoxal line recurved and complete; male with 5th ventrite with large setose foveae. 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 distinctly elongate, triangular; 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
Rodatus is endemic to Australia and is found in the coastal and inland regions of southern Queensland and New South Wales (including ACT); Victorian Alps and south east South Australia and Tasmania. Biology of R. major (Blackburn) feeding on eggs of margarodid scale Monophlebulus pilosior (Maskell) has been studied by Richards (1985). Larvae produce massive wax encrustation and have been found to complete their life cycles in ovisacs only. Both prepupa and pupa are also covered by a protective waxy shroud.
Mulsant, M E. 1850. Species des Coléoptères Trimères Sécuripalpes. Annales des Sciencies Physiques et Naturelles, díAgriculture et díIndustrie, publiées par la Société nationale díAgriculture, etc., de Lyon, Deuxième Série, 2: xv + 1-1104 (part 1 pp. 1-450; part 2 pp. 451-1104).
Richards, A. M. 1985. Biology and defensive adaptations in Rodatus major (Coleoptera: Coccinellidae) and its prey, Monophlebulus pilosior (Hemiptera: Margarodidae). Journal of Zoology (Series A), 205: 287-95.</<br>
Slipinski, S.A. 2007. Australian Ladybird Beetles (Coleoptera: Coccinellidae) their biology and classification. ABRS, Canberra. 286 pp.
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