Key to adult species of Xenomyia (partially based on Emden 1951 and Pont & Werner 2003)

1. Frontal vitta well-developed and much broader than the fronto-orbital plate and not covered with short dense setulae (Fig. 10); proboscis short, stout and bulbous (Fig. 5); ocellar setae present................................................ 2

1’. Fronto-orbital plates enlarged and covered with short dense setulae (Figs 12, 13); proboscis slender, elongate (Fig. 8); ocellar seta absent......................................................................................... 11

2. Profile of head at antennal base much longer than at mouth part, forming an acute angle, claws long and strong................................................................................................ X. natalensis Zielke

2’. Not with this combination of characters (if profile of head at antennal base much longer than at mouth part and forming an acute angle then claws small)................................................................................ 3

3. Profile of head at antennal base not longer than at mouth part, forming an obtuse angle (e.g. Fig. 10), claws long and strong.. ................................................................................................... 4

3’. Profile of head at antennal base much longer than at mouth part, forming an acute angle (e.g. Figs 4, 5 and 6), claws small.. 8

4. Anepimeron setulose................................................................. X. pseudolispe Emden

4’. Anepimeron bare..................................................................................... 5

5. Hind tibia with the anterodorsal seta on basal third, very long and fine in male (Fig. 17).............. X. hirtibasis (Bigot)

5’. Hind tibia with the anterodorsal seta on middle or apical third or absent.......................................... 6

6. Katepisternals 1+1; palpus not enlarged or dilated apically...................................... X. bispina Emden

6’. Katepisternals 0+1; palpus narrowly or strongly enlarged, dilated apically, flattened, spoon-shaped.................... 7

7. Palpus narrowly enlarged, dilated; claws very long (Fig.19), longer than the antenna; male hind tarsus strongly compressed and very short, joints 1–5 wider than long (Fig. 19);.............................................. X. perplexa Emden

7’. Palpus very strongly enlarged, dilated (Fig. 15); claws moderately long, not longer than antenna; male with hind tarsi not modified.............................................................................. X. palpalis Emden

8 Hind tibia with posterodorsal seta beyond middle........................................................... 9

8’ Hind tibia without posterodorsal seta.................................................................... 10

9. Dorsocentral presutural setae absent; eyes bare................................................. X. atra Malloch

9’. Dorsocentral presutural seta present; eyes densely covered with short hairs......................... X. setulosa Zielke

10. Fore tarsus with last two segments of normal shape........................................... X. acuticeps Emden

10’. Fore tarsus with last two segments dorsally broadened...................................... X. stuckenbergi Zielke

11. Prosternum setulose; vein R 1 setulose on middle section; katepisternals 0+2....................... X. edwardsi Emden

11’ Prosternum bare; vein R 1 bare throughout; katepisternals 1+2................................................. 12

12 Presutural intra-alar seta (inner posthumeral) absent; lower calypter elongate, more than twice (in male more than four times) as long as wide (Fig. 21) ………………................................................... X. calyptrata Emden

12’ Presutural intra-alar seta (inner posthumeral) present; lower calypter of normal shape, not more than one and a half times as long as wide........................................................................................ 13

13 Hind tibia with one anteroventral seta beyond middle........................................ X. azurescens Emden

13’ Hind tibia without anteroventral seta.................................................................... 14

14 Postpedicel somewhat acuminated at apex; mid femur with 2 posterior preapical setae................ X. oxycera Emden

14’ Postpedicel rounded at apex; mid femur with only 1 posterior preapical seta..................................... 15

15 Postpronotum with 1 seta; hind femur without anteroventral seta; male wing with a dark suffusion formed by dense microtrichia (Fig. 24)....................................................................... X. osculata Pont & Werner

15’ Postpronotum with 2 setae; hind femur with 1 anteroventral seta in apical third; male wing hyaline..... X. patersoni Zielke