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

1 Male. ........................................................................................................................... 2

– Female. ........................................................................................................................ 3

2(1) Gonostylus (in widest extension view, Figs 466, 473, 508, 509) with anterior margin distinctly convex. Thorax less densely grey to greyish brown microtomentose (Fig. 481) and with mesonotum usually subshining anteriorly. ............ A. shewelli sp. nov.

– Gonostylus (in widest extension view, Figs 493, 510–512) with anterior margin concave to almost straight. Thorax with dense grey microtomentum (Fig. 483), often with some bluish tinge (including mesonotum anteriorly). ............. A. gilviventris sp. nov.

3(1) T7+S7 entirely orange yellow to pale orange brown, sometimes with only a very narrow diffuse darkening on posterior margin and small brown marks on anterolateral lobes, OR only dorsolaterally narrowly brownish-darkened at posterior margin and ventrally with distinct and contrasting dark brown anterolateral lobes (Figs 484, 496, 517). ........................................................................... A. gilviventris sp. nov. (in part)

– T7+S7 dorsolaterally with at least posterior quarter (Figs 458, 474), largely (Fig. 515) to entirely (Figs 482, 502) dark brown, never as above. ............................................ 4

4(3) Spermathecae relatively large, the larger one 0.9–1.2 times as long as medial length of S10, usually more elongately ovoid and with sparsely striated surface (Figs 479, 480). T7+S7 with microtomentose area below 7th spiracle unpigmented, narrowly depressed and usually separated from dorsal darker part by a more or less distinct lateral ridge (Fig. 516). Thorax usually less densely grey to greyish brown microtomentose (as in Fig. 481) and with mesonotum usually subshining anteriorly (Figs 2, 458). ................ ...................................................................................................... A. shewelli sp. nov.

– Spermathecae relatively small, 0.6–0.8 times as long as medial length of S10, usually more broadly ovoid and with more densely striated surface (Figs 494, 498, 501, 505, 514). T7+S7 with microtomentose area below 7th spiracle pale- to dark-pigmented, nat, usually without lateral ridge (Fig. 517). Thorax with dense grey (often with some bluish tinge) microtomentum and, including mesonotum anteriorly, almost dull (Figs 482, 484). ................................................................... A. gilviventris sp. nov. (in part)