Female, CNC, UNITED STATES. Holotype locality: Aztec Peak, Arizona, USA.

First label: Aztek Pk., AR./coll. vi-1-77/em. vi-24/Torg. 1977 7065A. Second label: Ex Orgya pseudotsugata. Third label: Hopk. US/65254. Fourth label: CNC666525.

11♀, 17 ♂ (CNC) from the following localities. Canada: AB, Pincher Creek; BC, Carquile; BC, Elko; BC, Mount Lolo; BC, Nelson; BC, Lake Williams. United States: AZ, Aztec Peak, Tonto National Forest; CA, El Dorado County, Iron Mountain; CA, San Bernardino County, Sky Forest; CA, Stowe Reservoir; CA, Modoc County, Tom’s Creek; OR, Chiloquin Ridge; OR, Forth Klamath. Voucher codes: CNC841809– CNC841836. All of the specimens were reared, with emergence dates from early June to early August.

The enlarged eyes and ocelli of G. pseudotsugae are unlike those of any other described species of Glyptapanteles in North America –all of which have normal-sized eyes. The antenna of females is also rather long, with the last flagellomeres not significantly reduced, as it is the case with most Microgastrinae female specimens. The size of eyes and ocelli, the relatively long antenna, and the yellow-brown body coloration are all morphological features that strongly suggest this species is nocturnal or crepuscular – see Quicke (2015) for a summary and further references on the suite of characters that are typical of nocturnal/crepuscular parasitoid wasps. The caterpillar hosts are also unique among known hosts of Microgastrinae (see below).

Female. Body mostly brown to dark brown (except for yellow scape, pedicel, labrum, mandibles, palpi, tegula; humeral complex half yellow and half brown; T3+ partially yellow; anterior laterotergites and sternites mostly yellow; hypopygium sometimes partially yellow); most of legs yellow, but metacoxa, apical 0.1 of metafemur and metatibia, and metatarsus brown. Wings hyaline, pterostigma brown, veins mostly transparent (except for a few veins closer to pterostigma). Body mostly smooth and shiny, at most with fine, shallow and sparse punctures; propodeum with small striae around nucha; apical 0.3 of T1 and most of T2 (except centrally) with relatively coarse longitudinal striation. Head with eyes and ocelli enlarged. Protarsus with a thick and curved seta. Fore wing with veins r and 2RS meeting at a sharp angle, with vein 3RSa being a very small stub; vein R1 longer than pterostigma. Legs with tarsal claws simple. T1 narrowing towards posterior margin, T2 subtriangular (trapezoidal). Ovipositor sheaths with a few, large setae near tip. Body measurements (mm). Body L: 3.3 (3.2–3.7); fore wing L: 3.6 (3.7–4.1); ovipositor sheaths L: 0.15–0.20 (approximate measurement); metafemur L/W: 1.02/0.25 (1.04/0.25); metatibia L: 1.18 (1.22–1.24); metatibia inner/outer spurs L: 0.33/0.26 (0.32–0.36/0.24–0.26); first segment of metatarsus L: 0.48 (0.50–0.55); F2/3/14/15/16: 0.32/0.30/0.15/0.14/0.16 (0.31–0.32/0.29–0.30/0.14–0.15/0.13/0.15–0.16); ocular–ocellar line: 0.06 (0.04–0.07); interocellar distance: 0.12 (0.10–0.13); posterior ocellus diameter: 0.11 (0.11–0.12).

Male. As female, but eyes not enlarged, and general coloration, especially on metasoma, darker.

Compared to the US specimens, the Canadian specimens are darker (dark brown to black scape, clypeus, labrum and most tergites) and also slightly larger (0.1–0.2 mm longer wings and body).

Western North America, from 33°–52°N. Canada: AB, BC. United States: AZ, CA, OR.

The US specimens of Glyptapanteles pseudotsugae were all reared from the Douglas-fir tussock moth, Orgya pseudotsugata (McDunnough, 1921) (Lymantriidae), while the Canadian specimens were reared from three different species of Geometridae: the Spruce-fir looper Macaria signaria dispuncta (Walker, 1860), the Brown-lined looper Neoalcis californiaria (Packard, 1871), and Pero behrensarius behrensarius (Packard, 1871). Most of the specimens we examined had remnants of the host larva and/or the wasp cocoon preserved (kept in a gel capsule, pinned or glued to the paper where the adult wasp was mounted); based on that evidence, the parasitoid is considered to be solitary. Glyptapanteles pseudotsugae is the first species of Microgastrinae recorded attacking those four species of Lepidoptera. [There actually is an earlier mention of this wasp species, as an unidentified “Apanteles sp.”, in a previous publication studying the parasitoids and predators of Orgya pseudotsugata (Dahlsten et al. 1977); that is to be expected as all Glyptapanteles species were considered to belong to Apanteles until Mason (1981) split the latter genus into several]. The four lepidopteran hosts recorded above all feed on Douglas fir Pseudotsuga menziesii (Mirb.) Franco.

Named after the genus name of the Douglas fir, Pseudotsuga, as that plant harbours all caterpillar species that are host of the parasitoid wasp in North America.

Glyptapanteles pseudotsugae is an example of niche-based selection of caterpillar hosts by a parasitoid wasp, as all of the Lepidoptera species recorded here coexist on fir forests in North America (e.g., Mason 1987). That contrasts with the recorded information for most Microgastrinae wasps, which usually parasitize taxonomically related hosts. Despite the relatively wide geographical distribution of the species in western North America (the distance between the southernmost known specimens in central Arizona and the northernmost known specimens in southern British Columbia is approximately 2,500 km), and the different hosts species parasitized across the wasp range, only minor morphological differences are apparent, and thus the US and Canadian wasp specimens are here considered to be conspecific. Many of the US specimens from the type series detailed above come from Dahlsten et al. (1977), although those authors saw additional specimens not seen nor studied for this paper. No molecular data is known for this species.