Key to males of E. ( Enoplempis) east of the Rocky Mountains

1 Hind femur and tibia without processes, setal cones or distinct combs of setae (Figs 3 A, E, 6E, 12E, 19A, D, E); hind tro- chanter with (Figs 3 C, E, 9D, 12D, 16B, 19C) or without modified setae or processes................................ 2

- Hind femur and/or tibia with subapical/subbasal processes, setal cones or distinct combs of setae (Figs 6 A, D, 9A, E, 12A, C, 16A, C, 23A); hind trochanter lacking modified setae........................................................ 11

2 Hind trochanter bearing modified setae or processes (Figs 3 C, 9D, 12D, 16B, 19C)................................. 3

- Hind trochanter unmodified, setae unmodified............................................................. 8

3 Thoracic pleura yellow, in contrast to dark, greyish scutum. Hind trochanter with 5–8 stout setae widespread, not confined to process or arising from single spot (Fig. 3 C)............................................... E. (En.) amytis Walker

- Thoracic pleura greyish, concolorous with scutum (Fig. 3 D). Hind trochanter with stout setae confined to process or arising from single spot; if setae more widespread, then greater than 8 present (Figs 9 D, 12D, 16B, 19C)..................... 4

4 Hind tibia with numerous rows of long slender dorsal setae, longer than width of tibia (Figs 3 E, 12E).................. 5

- Hind tibia with only widely spaced setae, at most only slightly longer than width of tibia (Figs 9 C, 16B, 19B)........... 6

5 Setae of hind trochanter confined to distinct spot or short tubular process (Fig. 12 D). Apex of phallus expanded, funnel-shaped (Fig. 15 A)............................................................................ E. (En.) nuda Loew

- Setae of hind trochanter widespread, not confined to distinct spot or short process (Fig. 3 E). Apex of phallus slender, tapered to narrow apex (Fig. 4 B)................................................... E. (En.) appalachicola Sinclair sp. nov.

6 Setae of hind trochanter widespread, not confined to distinct spot or process (Fig. 19 C). Wing length less than 6 mm ....................................................................................... E. (En.) stenoptera Loew

- Setae of hind trochanter confined to distinct spot or process (Figs 9 C, 16B). Wing length greater than 6 mm ............. 7

7 Setae of hind trochanter confined to distinct tubular process (Fig. 9 D). Hypandrium 0.5× length of epandrium (Fig. 10 A), apex tapered and rounded; setae present on membrane anterior to base of hypandrium.............. E. (En.) gulosa Coquillett

- Setae of hind trochanter confined to distinct spot, not raised on tubercle (Fig. 16 B). Hypandrium short, about one-third length of epandrium (Fig. 17 A), apex notched; setae absent from membrane anterior to hypandrium................................................................................................... E. (En.) penicillata Brooks sp. nov.

8 Scutum with three distinct narrow vittae. Wing with clouding at base of R4 and apex of discal cell (Fig. 2B). Hind femur robust with anterior row of ventral spine-like setae (Fig. 19 D)................................. E. (En.) tridentata Coquillett

- Scutum with 2 or 4 indistinct broad vittae. Wing lacking clouding. Hind femur more slender, lacking ventral row of stout setae (Figs 6 E, 19A, E)..................................................................................... 9

9 Hind femur and tibia stout, with some spine-like setae; hind femur lacking rows of very slender, pale ventral setae (Fig. 6 E). Epandrium quadrate, not tapered posteriorly; hypandrium prolonged posteriorly, 0.5× length of epandrium (Fig. 8 A)........................................................................................ E. (En.) enodis Melander

- Hind femur and tibia long and slender, lacking spine-like setae; hind femur with rows of very slender, pale ventral setae (Figs 19 A, E). Epandrium tapered posteriorly; hypandrium short, less than half length of epandrium (Figs 20 A, 21B)......... 10

10 Apex of epandrium greatly narrowed, less than half width of base of epandrium (Fig. 20 A). Posterior margin of hypandrium truncate, not produced posteriorly; bearing long setae greater than length of hypandrium. Cercus broad apically with numerous sinuous setae..................................................................... E. (En.) snoddyi Steyskal

- Apex of epandrium not greatly narrowed, more than half width of base of epandrium (Fig. 21 B). Posterior margin of hypandrium produced, rounded; bearing short setae less than length of hypandrium. Cercus greatly narrowed on posterior third, bearing numerous straight, stout setae.......................................... E. (En.) vockerothi Cumming sp. nov.

11 Hind femur and tibia with dense rows of preapical setae, lacking highly modified processes (Figs 6 D, 12C, 16A)....... 12

- Hind femur and tibia with highly modified processes (Figs 6 A, 9A, E, 12A, 16C, 23A)............................ 14

12 Hind femur lacking preapical row of dense setae, only hind tibia with dense setae (Fig. 6 D). Epandrium quadrate with angular margins and fused anterodorsally to cercus (Fig. 7 B).................................. E. (En.) ctenocnema Melander

- Hind femur with preapical posteroventral and/or anteroventral row of dense setae, similar to setae of tibia (Figs 12 C, 16A). Epandrium more rounded apically, not fused to cercus (Figs 13 B, 15B).......................................... 13

13 Hind femur with anteroventral preapical row of stout setae (Fig. 12 C). Base of hind tibia with pair of antero- and posteroventral rows separated by clear gap (Fig. 12 C). Hypandrium with setae longer than length of sclerite (Fig. 13 B)........................................................................................... E. (En.) nodipoplitea Steyskal

- Hind femur with antero- and posteroventral preapical rows of stout setae (Fig. 16 A). Base of hind tibia with rows of setae dense, not separated by clear gap (Fig. 16 A). Hypandrium with setae shorter than length of sclerite (Fig. 15 B)...................................................................................... E. (En.) pectinata Sinclair sp. nov.

14 Thoracic pleura primarily yellow....................................................................... 15

- Thoracic pleura primarily greyish, not predominantly yellow................................................. 16

15 Base of hind tibia with pair of slender ventral processes with narrow brush of black apical setae (Figs 12 A, B). Hypandrium clothed in long, dense setae (Fig. 13 A). Phallus without lateral projections, only slightly tapered towards apex (Fig. 13 A).......................................................................... E. (En.) montywoodi Brooks sp. nov.

- Base of hind tibia with pair of blunt ventral processes, posteroventral process distinctly tufted, anteroventral process anvilshaped (Figs 16 C, D, E). Hypandrium with setae shorter, confined to base (Fig. 17 B). Phallus flanked by stout lateral pointed projections, medial portion denticulate and slender apically (Fig. 17 B)............. E. (En.) prodigiosa Cumming sp. nov.

16 Hind tibia with setae subequal to or shorter than width of segment (Figs 6 A, 23A). Hind femur with tufted preapical anteroventral process (Figs 6 B, 23B)............................................................................ 17

- Hind tibia with setae longer than width of segment (Fig. 9 E). Hind femur lacking tufted preapical anteroventral process (Figs 9 A, B, F, G)........................................................................................ 18

17 Base of hind tibia geniculate and highly excavated, fitting posteroventral processes of femur (Figs 6 B, C); apical half of phallus straight, directed dorsally (Fig. 7 A)............................................... E. (En.) arthritica Melander

- Base of hind tibia not geniculate, with pair of tufted processes (Figs 23 B, C); apical half of phallus strongly arched, directed anterodorsally (Fig. 24)....................................................... E. (En.) volsella Sinclair sp. nov.

18 Base of hind tibia with thumb-like process clothed with short, fine setae (Fig. 9 A). Hind femur with hooked, posteroventral preapical process longer than width of femur (Figs 9 A, B)............................... E. (En.) gladiator Melander

- Base of hind tibia with bare, elongate, pointed triangular process (Figs 9 F, G). Hind femur with triangular, posteroventral preapical process shorter than width of femur (Figs 9 F, G)............................... E. (En.) loripedis Coquillett