Microdontinae

Cheng, Xin-Yue & Thompson, Christian, 2008, A generic conspectus of the Microdontinae (Diptera: Syrphidae) with the description of two new genera from Africa and China, Zootaxa 1879, pp. 21-48 : 23-24

Key to the groups of the subfamily Microdontinae

1. Postmetacoxal bridge incomplete; metathoracic anepimera not fused; proanepisternum enlarged, usually with vertical row of long strong pile; occiput with distinct crease on dorsal third (figs 34–35). Vein R4+5 without an appendix (fig. 32) (Tribe Spheginobacchini )............................................................................41

- Postmetacoxal bridge complete; metathoracic anepimera fused medially to form bridge; proanepisternum not greatly enlarged and not with row of long strong pile; occiput without creases (tribe Microdontini )...2

2. Vein R4+5 with an appendix extending posteriorly into cell R4+5 (figs 28, 44, 48–49).......................... 15

- Vein R4+5 without such an appendix (figs 1, 5, 10, 24, 32–33)..................................................................3

3. Either vein M1 processive, directed outwardly and cell R4+5 with acute apex (fig. 33); or face with a distinct tubercle under antennae; metasternum underdeveloped, bare (fig.40) (Neotropical) ........................12

- Never with vein M1 processive, either straight or slightly recurrent; face without a tubercle under antenna ....................................................................................................................................................................................... 4

4. Abdomen petiolate; vein M with a short appendix extending anteriorly into cell R4+5 (as in fig, 32); metasternum under developed, reduced to thin line, bare (fig. 40) (New World) ....................... Mixogaster

- Abdomen not petiolate, oval to elongate; vein M without such an appendix...............................................5

5. Scape very short, only as long as broad; antenna inserted dorsally on head, at or above dorsal margin of eye (fig. 46); mouthparts absent; male basoflagellomere with multiple furcations (fig. 47) (southern South America) ....................................................................................................................................... Masarygus

- Scape long, much longer than broad (figs 3, 12, 38–39, 43); antenna usually inserted medially, much ven-

tral to dorsal margin of eye; mouthparts present; male basoflagellomere usually normal, not multiply fur- cate, at most with only two branches............................................................................................................6 6. Postpronotum bare; thorax and abdomen with long thick black bristle-like pile; katatergum bare and smooth on dorsoanterior 1/2 ............................................................................................................ Surimyia

- Postpronotum pilose; thorax and abdomen without such black bristle-like pile; katatergum microtrichose and rugose.....................................................................................................................................................7

7. Anepimeron bare or with a few long pili on dorsal edge; antenna short, only about 2 as long as face (fig. 36); abdomen oval (Neotropical) .................................................................................................. Paragodon

- Anepimeron generally pilose; antenna usually long, usually longer than 2 as long as face; if shorter, then abdomen elongate.........................................................................................................................................8

8. Abdomen oval.............................................................................................................................................13

- Abdomen narrow, parallel-sided or triangular (figs 19, 16–17, 24) .............................................................9

9. Occiput uniform, as wide dorsally as ventrally (fig. 39); metatibia narrow, with long pile; abdomen elon- gate; small, pale orange to yellow flies (fig.24) (Neotropical) ........................................................... Rhoga

- Occiput broad dorsally, narrow ventrally (figs 13, 38); metatibia usually without long pile, if with long pile, then pile thick and abdomen triangular (fig. 17)................................................................................10

10. Metatibia broad medially, with row of long pile along dorsal edge (figs 11, 20).......................................38

- Metatibia narrow, without distinct brush of long pile (fig. 42)...................................................................11

11.Transverse suture incomplete medially; anepisternum pilose only on anterodorsal corner and narrowly along posterior edge; metasternum usually pilose (Neotropical, Oriental) ............................ Paramicrodon

- Transverse suture distinct, continuous across scutum; anepisternum uniformly pilose, without bare medi- ally area; metasternum bare (Oriental) ............................................................................................. Indascia

12. Face with a dorsomedial tubercle under antenna; profemur with a distinct spinose pad on basal 1/4 or more ................................................................................................................................... Eurypterosyrphus

- Face straight or convex, without such a tubercle; profemur without spinose pad .................. Aristosyrphus

13. Basoflagellomere not furcate, at most twice as long as scape (fig. 1) (Afrotropical) ........... Afromicrodon

- Male basoflagellomere furcate; female basoflagellomere greatly elongate, 3 or more times as long as scape (Neotropical, Oriental)......................................................................................................................14

14. Metasternum developed, pilose; katepisternum pilose; scutellum medially excavated (fig.) (Oriental China) ........................................................................................................................................ Furcantenna

- Metasternum reduced, bare; katepisternum bare; scutellum convex apically (Neotropical).......................... ........................................................................................................................................... Schizoceratomyia

15. Abdomen oval or parallel-sided..................................................................................................................22

- Abdomen petiolate; 2nd segment flattened, sometimes constricted or with large basolateral pale macula; 3rd and 4th (males) or 5th (females) forming a club..................................................................................16

16. Basoflagellomere 3 to 5 times as long scape (fig 43) (Oriental, Australian) ....................... Paramixogaster

- Basoflagellomere never more than twice as long as scape (fig. 30)...........................................................17

17. Katepimeron pilose (Southern Nearctic, Neotropical) ......................................................... Rhopalosyrphus

- Katepimeron bare........................................................................................................................................18

18. 2nd abdominal segment cylindrical, longer than thorax (fig. 18); thoracic pile very short and strongly appressed; postpronotum, anterior anepisternum and metasternum appearing bare even under high magni- fication (Neotropical) Ceriomicrodon

- 2nd segment shorter than thorax; thoracic pile longer, erect; postpronotum, anterior anepisternum and metasternum usually with long distinct pile...............................................................................................19

19. Metasternum bare.......................................................................................................................................21

- Metasternum pilose.....................................................................................................................................20

20. Vertex swollen, shiny, bare at least anteriorly. Gena reduced, narrow, usually not visible in lateral view