J. HYM. RES. Vol. 10(2), 2001, pp. 113-118 A New Species of the Genus Orussonia Riek and the Female of O. depressa Riek (Hymenoptera: Symphyta, Orussidae) Stefan Schmidt and Gary A. P. Gibson (SS) Australian National Insect Collection, CSIRO Entomology, Canberra ACT 2601, Australia (e-mail:
[email protected]); (GAPG) Systematic Entomology Section, Eastern Cereal & Oilseed Research Centre, Agriculture and Agri-Food Canada, K.W. Neatby Building, 960 Carling Avenue, Ottawa, Ontario, Canada, K1A 0C6 (e-mail:
[email protected]) Abstract. — Orussonia ruficaudata Schmidt and Gibson, new species, and the female of O. de-pressa Riek are newly described; the male of O. depressa is redescribed and differential features of the species and of the sexes of O. depressa are illustrated. Riek (1955) established the genus Orus-sonia for two males collected in 1952, which he described as O. depressa. One of us (GAPG) recently collected two females that we associate as the opposite sex of O. de-pressa. We also discovered in the Austra-lian National Insect Collection a third fe-male, collected many years earlier in 1919, which Riek had identified as a second un-described species and labelled with the manuscript name O. ruficaudata. Here we describe what we consider to be the female of O. depressa and the female of this second species, which we name O. ruficaudata. Orussonia is one of three genera of Orus-sidae occurring in Australia (Riek 1955). The other two genera are Guiglia Benson with at least four Australian species (Ben-son 1955, Riek 1955, Vilhelmsen, pers. comm.) and Orussobaius with six species from Australia and one from New Guinea (Schmidt and Vilhelmsen, in prep.). The genus Orussonia constitutes, together with genera traditionally placed in the tribe Lep-torussini by Benson (1955), a paraphyletic group comprising the basalmost lineages of the Orussidae (Vilhelmsen, pers. comm.). Females of species of the genus Orussonia possess two pairs of medially separate coronal teeth (Figs 1, 3) and an in-complete ventral transverse frontal carina, whereas in most other orussid genera there are at least three pairs of medially separate coronal teeth and a fully developed ventral transverse frontal carina (Vilhelmsen, pers. comm.). Among all orussids Orussonia is the only genus with an extremely dorso-ventrally flattened body and a prognathous head and is, therefore, easily recognisable. Nothing is known about the biologv of Orussonia, but the flattened body shape might indicate that they crawl under loose bark. It is known for some beetles with dorsoventrally flattened bodies that they occur under bark, e.g. species of the genus Platisus (Coleoptera, Cucujidae) (Lawrence and Britton 1991). METHODS The holotype female and male of O. ruf-icaudata and O. depressa, respectively, were used for the scanning electron micro-graphs. All specimens were uncoated and digital images were obtained with a Phil-ips XL 30 ESEM. The low vacuum envi-ronmental scanning mode was used for all except Fig. 1, which was obtained under high vacuum. A 1 mm cone aperture was used during low vacuum mode to im-prove image quality, which resulted in a circular image format at low magnifica-tions. The digital images were enhanced
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