PROC. ENTOMOL. SOC. WASH. 97(3), 1995, pp. 569-581 THE NORTH AMERICAN SPECIES OF SYSTASIS WALKER (HYMENOPTERA: PTEROMALIDAE) S. L. Heydon Bohart Museum, Department of Entomology, University of California, Davis, Cali-fornia 95616. Abstract.— The nearctic species of Systasis Walker are reviewed. These include two holarctic species, S. encyrtoides Walker and S. parvula Walker, and three new nearctic species— 5. aquila, n. sp., S. hansoni, n. sp., and S. tena, n. sp. A summary of the biology and distribution for the genus and for each species is presented. Key Words: Systasis, Semiotellus, Pteromalidae, Ormocerinae, Cecidomyiidae, gall, blueberry, biology, new species Systasis Walker, 1834, and Semiotellus Westwood, 1839, were placed together in a new tribe, the Systasini (Ormocerinae), by Boucek (1988). Systasini is defined on the basis of reduction in the number of antennal segments to 12 with at least the two basal flagellar segments anelliform (Figs. 4, 6, 8-1 1), reduction of the number of teeth on each mandible to 3 (Fig. 2), and the uniquely structured clypeus— quadrate, nearly flat, with the anterior margin nearly straight across, and with deep anterior tentorial pits in the dorsolateral comers (Figs 1, 2). Two other unusual characters present in most species of these two genera and which need more study of their distribution are 1) the tendency of the mesepistemum to be non-metallic, varying from almost black to dull yellowish brown depending on the species, and 2) the presence of a narrow membra-nous fovea basally on the dorsolateral cor-ner of the gaster. Systasis and Semiotellus are very similar genera, and if the morpho-logical variation found in the Nearctic spe-cies described herein is taken into account, Systasis species are distinguished from those of Semiotellus only in having 1) the spec-ulum of the upper surface of the wing ex-tending down to the stigmal vein, making the line of strong setae on the ventral side of the wing membrane just posterior to the marginal vein easily visible and 2) the free anterior margin of the clypeus nearly straight across (Fig. 2). Semiotellus species have the dorsal surface of the fore wing setose pos-terior to the marginal vein and the free an-terior margin of the clypeus truncate. It is probable that these two genera will someday be regarded as subgenera of Systasis once a worldwide survey of the species is com-pleted. Systasis was originally created for the spe-cies -S. encyrtoides Walker and S. temucornis Walker. Current authors recognize eight ad-ditional palearctic species— S. acuta (Fon-scolombe), S. annulipes (Walker), S. an-gustula Graham, S. hasiflava Graham, 5". ephedrae Dzhanokmen, S. longida Boucek, S. parvula Thomson, and S. tenuicornis Walker; four Oriental species— 5. cenchri-vora Farooqi & Menon, S. dalbergiae Mani, S. dasyneurae Mani (key to these three spe-cies in Farooqi and Menon 1972), and S. vischnu (Motschulsky); 21 Australian spe-cies— 5". australiensis (Girault), S. cecido-myiae (Ashmead), 5". cecili Girault, S. cer-
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