Synonyms
Scymnus Kugelann, 1794: 545. TS: Scymnus nigrinus Kugelann, 1794.
Scymnus (Pullus) Mulsant, 1846: 241. TS: Coccinella subvillosa Goeze, 1777.
Scymnus (Nephus) Mulsant, 1846: 237. TS: Sphaeridium quadrimaculatum Herbst, 1783.
Scymnomorpha Blackburn, 1892: 242. TS: Scymnomorpha duplopunctulata Blackburn, 1892.
Midus Blackburn, 1892: 260 (misidentification).
Diagnosis
Scymnus can be distinguished from all small or medium sized setose Australian genera by its complete and recurved abdominal postcoxal line; antenna shorter than head, 11- or 10-segmented with distinct 3-segmented club; eyes finely facetted and not emarginate and prosternal carinae almost always present.
Description
Length 1-3 mm. Head dorsally not covered by pronotum; body elongate-oval and moderately convex; winged; dorsum uniformly hairy. Elytral colour variable. Head transverse; eyes finelly facetted, not emarginate. Antenna 10- or 11-segmented; slightly shorter than head capsule with scape and pedicel subequal; antennomere 3 elongate; antennal club 3-segmented. Terminal maxillary palpomere parallel sided or weakly expanded apically. Pronotal disc evenly convex. Prosternum moderately long in front of coxae, straight; prosternal process very broad with or without complete carinae. Anterior margin of mesoventrite straight medially. Mesoventrite slightly narrower than coxal diameter; Metaventral postcoxal lines strongly recurved. Elytral epipleuron very narrow, incomplete apically, not foveate. Tibial spurs absent. 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 tube-like, enclosing the sperm duct; sperm duct simple, uniform in diameter. Spermatheca worm-like, without clear ramus or nodulus; spermathecal accessory gland distinctly separated from sperm duct.
Distribution and Biology
Worldwide. Little information is available on biology of these cryptic ladybirds. It appears that species of the subgenus Scymnus s.str. and Pullus are predominantly aphid predators and their larvae are covered by waxy secretion moving freely about aphid colonies. Almost nothing is known about biology of Australian species except that some species have been collected feeding on various scale insects.
Genus References
Blackburn, T. 1892. Further notes on Australian Coleoptera, with descriptions of new genera and species. XII. Transactions of the Royal Society of South Australia, 15(2): 207-61.
Gordon, R D. 1976. The Scymnini (Coleoptera: Coccinellidae) of the United States and Canada: Key to genera and revision of Scymnus, Nephus and Diomus. Bulletin of the Buffalo Society of Natural Sciences, 28: 1-362.
Fürsch, H. 1987. Ubersicht uber die Genera und Subgenera der Scymnini mit besonderer Berucksichtigung der Westpalaearktis (Insecta, Coleoptera, Coccinellidae). Entomologische Abhandlungen, 51, (4): 57-74.
Iablokoff-Khnzorian, S. M. 1976. Die paläarktischen Genera der Marienkäfer - Tribus Scymnini nebst Bemerkungen über Scymnus fuscatus (Coleoptera, Coccinellidae). Etomologia Germanica, 2, (4): 374-80.
Kugelann, J. G. 1794. Verzeichniss der in einigen Gegenden Preussens bis jetzt entdeckten Käfer-Arten, nebst kurzen Nachrichten von denselben. Neuestes Magazin für die Liebhaber der Entomologie, 1, (5): 513-82.
Mulsant, M E. 1846. Histoire Naturelle des Coléoptères de France. Sulcicolles-Sécuripalpes. Maison, Paris. xxiv + 26 pp. + 280 pp. + 1 pl.
Sasaji, H. 1971. Coccinellidae (Insecta: Coleoptera). Fauna Japonica. Academic Press of Japan, Tokyo. 16 pls., 345 pp.
Slipinski, S.A. 2007. Australian Ladybird Beetles (Coleoptera: Coccinellidae) their biology and classification. ABRS, Canberra. 286 pp.
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