New species of parasitic wasps attacking cereal aphids in the Pacific Northwest (Hymenoptera: Braconidae: Aphidiinae).

Two new parasitoid species, Monoctonus washingtonensis sp. n. and Praon yakimanum sp. n. (Hymenoptera: Braconidae: Aphidiinae), reared from cereal aphids [Diuraphis noxia (Kurdjumov) and Rhopalosiphum padi (L.)] in Washington State are described and illustrated. The appearance of the Russian wheat aphid, Diuraphis noxia (Kurdjumov), and its negative impact on small grain crops, has stimulated research on the whole of the aphid parasitoid fauna in the Pacific Northwest. Recognizing the spectrum of parasitoid species attacking aphids is fundamental to understanding and as sessing their potential as natural control agents in agricultural, forest, rangeland, and urban settings. Two new species of parasitic wasps of cereal aphids in Washington State are named and described, and the key features illustrated. Description of New Species Monoctonus washingtonensis Pike & Stary, sp. n. diagnosis: This species can be distinguished from other Nearctic congeners (see Stary, 1974; Stary and Smith, 1976; Marsh 1979) by a 14-segmented (rarely 13) poorly pubescent antenna (female), the shape of the antescutal depression of the pronotum, the areolation of the propodeum, the shape and direction of the radial vein in relation to the pterostigma, and the presence of distinguishable fused radial and medial cells in the forewing. etymology: The name of the new species is derived from its known distri bution, Washington State. description: Female: Head. Eyes sparsely haired. Malar space V6 to V5 eye length. Tentoriocular line % to V3 intertentorial line. Face with sparse hairs over surface and with single rows of hairs along eye margins. Clypeus with sparse, long hairs. Maxillary palpus 4-segmented, labial palpus 2-segmented. Antenna 14 segmented (rarely 13), reaching to middle of metasoma; flagellum somewhat thick ened in apical half, flagellomere 1 (= F^ (Fig. lb) slightly less than 4 times as long as wide, with sparse, long semierect hairs subequal in length to diameter of segment, without rhinaria. F2 (Fig. lc) slightly wider than Fj (15:14), 3 times as long as wide, with long semierect hairs equal in length to diameter of segment, with 0-1 rhinarium. Middle flagellomere, F7 (Fig. If), a little wider than F2 (17: 15), 2.5 times as long as wide, with sparse, long semierect hairs subequal to diameter of segment, with 2 rhinaria. Preapical flagellomere, F10 (Fig. lg), 2.5 times as long as wide, equal to F7 in width. 1 Washington State University, Irrigated Agriculture Research & Extension Center, Rt 2, Box 29 53A, Prosser, Washington 99350-9687, USA. 2 Institute of Entomology, Academy of Sciences of the Czech Republic, Branisovsk? 31, 370 05 Cesk? Bud? jovice, Czech Republic. Accepted for publication 14 April 1995. This content downloaded from 40.77. 167.104 on Fri, 07 Oct 2016 05:58:39 UTC All use subject to http://about.jstor. org/terms VOLUME 68, NUMBER 4 409 Mesosoma. Antescutal depression of pronotum (Fig. lj) wide, obtusely tri angular, almost reaching anterior margin of pronotum. Mesonotum (Fig. la) with notauli distinct in ascendent part, effaced on disc where they are each traced with a row of long sparse hairs, otherwise almost hairless except for a few hairs close to prescutellar groove. Propodeum (Fig. 1 d, e) areolate; lower lateral carinae always distinct, well-developed and definable; central, narrow areola variable in shape and structure; upper carinae from near complete to irregular rugosities with a few rings inside indicated areola. Forewing (Fig. lh). Pterostigma short and narrow, 6-7 times as long as broad. Metacarpus short, equal to V3 pterostigma length. Radial and medial cells confluent and well-defined. Apical half of fused intermedial and medial vein and lower half of interradial cross vein colorless. Radial abscissa 1 (Ra,) straight to slightly arcuate, almost perpendicular to pterostigma. Raj shorter than Ra2, but longer than greatest width of pterostigma. Interradial cross vein shorter than Ra1? but equal to greatest width of pterostigma. Posterior marginal hairs long, 3 times as long as surface hairs. Legs. Hind femur with long, sparse, semierect hairs, equal to 2/3 middle diameter of femur. Hind tibiae with long, sparse, semierect hairs, slightly greater in length than middle diameter of tibia. Metasoma. First metasomal tergite (Fig. Ik) twice as long as greatest width; surface coarsely rugose, with sparse long hairs; spiracles dorso-laterally prominent; interspiracular distance slightly greater than distance from spiracles to basal at tachment. Genitalia (Fig. li). Ovipositor sheath ploughshare-shaped; hairs semierect on anterior margin, uniform in length and equal to Vi widest diameter of sheath; hairs on posterior apex subequal to widest diameter of sheath. Coloration. Head brown. Mouthparts yellowish, apex of mandible brown. Scape, pedicel and base of F{ yellowish, remaining portion of F{ yellowish to brownish, remainder of antenna brown. Mesosoma brown; prothorax and pro podeum sometimes lighter. Wings subhyaline, venation light brown to brown. Tegulae light brownish. Metasoma brown, except tergite 1 yellow brown to light brown. Ovipositor sheaths brownish. Length of body about 1.7 mm. Male: Similar to female with some exceptions: antenna 17-segmented (rarely 16); coloration somewhat darker, mouthparts and legs light brownish, antenna brown, scape brownish, pedicel and narrow base of F, yellowish. Length of body about 1.6 mm. holotype: Female, Washington State University (cereal field), Prosser, Wash ington, 8 May 1992, D. Allison and K. S. Pike. Host: Rhopalosiphum padi (L.) on wheat. Deposited in USNM, Washington D.C., Type No. 105226. paratypes: Females, 9; males, 6; additional paratypes dissected and mounted on slides, same data as holotype, except deposited in the Washington State Uni versity Collection, James Museum, Pullman, Washington. Other material from R. padi (L.) and Diuraphis noxia (Kurdjumov) in the Washington State University Collection at Prosser, Washington and collection of P. Stary, Cesk? Bud? jovice, Czech Republic. remarks: The current Nearctic Monoctonus include not only indigenous spe cies, but also reported introduced European species (Mackauer, 1962; Stary and This content downloaded from 40.77. 167.104 on Fri, 07 Oct 2016 05:58:39 UTC All use subject to http://about.jstor. org/terms 410 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY