Key to identincation of the Nearctic species of the Anthomyza gracilis group

1 Head in pronle slightly higher than long; eye broad, little narrowed posterodorsally (Fig. 518); orbit dark from vertex beyond posterior ors, usually to about midway between posterior and middle ors (Fig. 519); in lateral view, narrow area above postgena anteriorly greyish but abruptly becoming shiny brown to black on occiput (Fig. 518); caudal process of male with ventral appendage more elongate (Fig. 532) and thin in lateral pronle (Fig 530) and lacking anteroventral angularity; aedeagal part of folding apparatus with strong spines ventrally (Figs 528, 534); female T7+S7 with ventral anteromedial area triangular and distinctly domed (medially convex), ventral desclerotized area small and without sclerotized posteromedial appendage (Figs 536, 538). ........................................................................................... A. furvifrons sp. nov.

– Head in pronle more depressed, longer than high; eye elongate, narrowed posterodorsally (Figs 520, 522); orbit dark only from vertex to posterior ors and abruptly yellow in front of it (Figs 521, 523); in lateral view, area above postgena somewhat broader and generally continuously greyish from margin of eye onto occiput (Figs 520, 522); caudal process of transandrium with ventral appendage less elongate (Figs 555, 584) and thicker in lateral pronle (Figs 553, 582) and anteroventrally more or less angular; aedeagal part of folding apparatus without strong spines ventrally (Figs 556, 558, 585, 587); female T7+S7 with ventral anteromedial area shorter and longitudinally grooved (Fig. 565, arrow) often producing a chordate posterior margin, ventral desclerotized area large and posteromedial appendage behind it well sclerotized (Figs 564–566, 568, 570, 589, 591). .................................................................................... 2

2(1) Thorax brownish grey to dark bronze microtomentose; midline sternal setae predominantly black. f 1 usually with at least some grey to brown darkening on posterior surface (Fig. 522), at least basal corner of cx 1 always dull grey- to brown-darkened, sometimes also other femora and tibiae partly darkened (Fig. 574) especially t 1 opposite the ctenidial spine; frons with medial darkening extending anteriorly to at least middle ors (Fig. 523) and as far as anterior margin; male preabdominal sterna dark, ochreous brown; caudal process of transandrium with ventral appendage widely naring ventrally (Fig. 582) and posteriorly (Figs 583, 584); female T7+S7 with pale-pigmented anteroventral strip broadly extended dorsolaterally (Fig. 591), reaching above 7th spiracle (Fig. 589), and shiny secondary posterolateral sclerotization prominent (Fig. 589, arrow); associated with horsetails ( Equisetum spp.). ................................. A. equiseti sp. nov.

– Thorax usually pale grey microtomentose; midline sternal setae predominantly pale (very rarely all black). All femora and tibiae entirely yellow (Figs 520, 545), cx 1 sometimes with a shiny brown darkening basally; frons with anterior margin usually broadly yellow (Fig. 521), rarely with medial darkening extending beyond middle ors; male preabdominal sterna pale, dirty yellowish; caudal process of transandrium with ventral appendage moderately naring ventrally (Figs 553, 561) and posteriorly (Figs 554, 555); female T7+S7 with pale-pigmented anteroventral strip not extended dorsolaterally (Figs 564, 565, 568), and shiny posterolateral sclerotization absent (Figs 564, 566); associated with grasses or sedges. ....................................... A. vulgaris sp. nov.