Key to species of Wilcoxia

1 Anterior dorsocentral setae of scutum long and erect (≥ length of scape + pedicel) (Figs 9–16); scutellum with 6–14 long, marginal setae, longer than antenna; mystax composed of long hairs of fairly uniform length and stoutness from oral margin to base of antennae (Figs 21–25); abdominal tergites (except male of W. forbesi, with uniformly pollinose tergites) with alternating pollinose and bare areas, vaguely in “checkerboard” pattern (Figs 30–33, 35–37); legs piceous to black with no contrasting, yellowish areas (Figs 9–16)............................................................ martinorum group…2

- Anterior dorsocentral setae of scutum short and appressed (about length of scape) (Figs 1–8); scutellum with 2–6 marginal setae, shorter than antenna; mystax with long hairs or setae confined to lower half or less of face (Figs 17–20); abdominal tergites with pollinose areas covering virtually entire tergite ( W. pollinosa only, Fig. 29), or present as bands along lateral and/or anterior and/or posterior margins only, not in a “checkerboard” pattern (Figs 26–28); legs with at least tibiae largely yellow (Figs 1–8).............................................................................. cinerea group…5

2 Sexes similar: abdomen grey pollinose; dorsum of tergite 1 with medial bare patch, and tergites 2–6 with bare patches on medial posterior margin, and anterior lateral bare patches (Figs 30–33, 36–37)........................................... 3

- Sexes different: male with abdominal tergite 1 bare medially, remainder densely grey pollinose (Fig. 34); mystax of very dense, long white hairs (Fig. 23); female with abdominal tergites 1–5 with lateral pollinosity, expanded toward midline posteriorly; tergites 2–5 with narrow anterior band of pollinosity (Fig. 35)................................ W. forbesi, new species

3 Outer lateral surface of all femora not pollinose (in some specimens, extreme distal end only pollinose); usually 2 postalar setae present; in most specimens, pair of short, linear non-pollinose patches present on scutum, between central stripe of scutum and postalar callosities (Fig. 41); knob of halter distinctly pinkish, contrasting yellow stem............ W. apache, new species

- Outer lateral surface of fore femur (in most specimens mid and hind femora also) pollinose; usually 1 postalar seta present; scutum without distinct, non-pollinose areas, or if slightly suggested, then not posterior of scutum midlength; knob of halter yellow, in some specimens with very slight pink tinge, not contrasting yellow stem................................. 4

4 Outer lateral surface of all femora largely pollinose; first abdominal tergite non-pollinose medially, with anterior edge of bare area wider than posterior margin; second abdominal tergite with medial bare area in most specimens isolated from lateral nonpollinose bare areas (Figs 36–37); wings hyaline, without yellow cast........................... W. martinorum Wilcox

- Pollinosity of mid and hind femora confined to distal 1/4 or less (fore femur with more extensive coverage in some specimens); first abdominal tergite as above, but with posterior edge of bare patch wider than anterior edge; second abdominal tergite medial bare area (usually) contiguous with lateral bare areas (Figs 32–33); wings hyaline, with slightly yellow cast........................................................................................... .. W. flavipennis, new species

5 Scutellum uniformly pollinose (e.g., Fig. 41); scutum with 2–3 pairs of small, semicircular non-pollinose patches or contrasting pollinose patches; scutellum with 2–3 posterior marginal setae................................................. 6

- Posterior margin of scutellum non-pollinose (e.g., Fig. 42); scutum uniformly pollinose, without 2–3 pairs of small, semicircular non-pollinose or contrasting pollinose patches; scutellum with 4–6 posterior marginal setae........................ 7

6 Abdominal segments 1–6 in female, 1–7 in male, with dense yellowish-grey pollinosity; several tergites with thinly pollinose or bare elliptical spots laterally and medially (Figs 7–8, 29); abdomen long and narrow (especially in male), segment 2 longer than wide; TL 9–11 mm ................................................................. W. pollinosa Wilcox

- Abdominal segments 1–6 in female, 1–7 in male, mostly non-pollinose with narrow lateral margin of grey pollinosity, expanded toward center posteriorly, and grey pollinosity on anterior margins of tergites 2–5 (Figs 5–6, 28); abdomen relatively shorter and wider, segment 2 wider than long; TL 4–8 mm ............................................. W. painteri Wilcox

7 Ratio of width of face: width of eye ≤ 0.7; femur with extensive piceous area, in females occupying> 1/2 length of femur, in males almost entire femur dark; tibiae with slight distal infuscation in female, in male distal 1/3 to 1/2 of tibiae infuscate, especially so on fore and middle legs (Figs 1–2); wings light brown, almost hyaline in female............... W. cinerea James

- Ratio of width of face: width of eye ≥ 0.8; femur with base and distal ~1/3 yellow-orange, with piceous region between; tibiae entirely yellow-orange, in some specimens slightly infuscated distally, especially on front legs (Figs 3–4); wings medium brown, lighter in female................................................................... W. monae Wilcox