Key to species of Acanthonevrini from India

1. Scutum red-brown with broad, fulvous prescutellar patch (Fig. 67); scutellum wholly yellow or white........................................................................................... Diarrhegma modestum (Fabricius)

- Scutum reddish brown/fulvous/black without yellow prescutellar patch (Figs 68–72); scutellum variable in colour........ 2

2. Scutum fuscous with brown, longitudinal vittae extending to scutellum (Fig. 68); cell r 1 1.5 times longer than cell sc, wing predominantly dark brown (Fig. 79) with apical hyaline spots in cells r 2+3 and r 4+5 .......... Rioxa parvipunctata de Meijere

- Scutum yellow/fulvous (Figs 71, 72) or black (Fig. 69) but without longitudinal vittae extending to scutellum; cell r 1 as long as or shorter than cell sc, wing pattern variable (brown with numerous hyaline wedges or spots/fully black/hyaline with longitudinal and transverse bands).................................................................................. 3

3. Scutum yellow/fulvous with black lateral postsutural vittae and spots; abdomen yellow/fulvous with transverse bands interrupted medially on tergites 2–5 in females and 3–5 in males (Figs 15, 16)................................................................................................... Tritaeniopteron obscurum David, Salini & Nikhil, sp. nov.

- Scutum fulvous/red-brown/black/fuscous but without black lateral postsutural vittae and spots; abdomen not as above..... 4

4. Scutum black with a prominent white stripe from scapular seta to apex of scutellum (Fig. 69) or brown with broad, black presutural and postsutural bands (Fig. 46); wing either fully black with posterior hyaline band (Fig. 77) or fully brown with anterior hyaline band (Fig. 47).......................................................................... 5

- Scutum and wing not as above.......................................................................... 6

5. Scutum black with a prominent fulvous stripe from scapular seta to scutellum (Fig. 69); wing black or predominantly black with vein M 1 strongly curved (Fig.77)............................................... Felderimyia fuscipennis Hendel

- Scutum brown with broad, black presutural and postsutural bands (Fig. 46); wing brown with a hyaline costal band (Fig. 47), vein M 1 parallel to R 4+5 ............................................. Felderimyia gombakensis Hancock & Drew

6. Scutum red-brown with dark presutural vittae and a prescutellar transverse band; wing yellow with dark brown band from sc to vein Cu 1 through apical margin of wing.................................................. Sophira phlox Munro

- Scutum not as above, without presutural vittae and transverse band; wing either hyaline or dark fuscous with hyaline markings........................................................................................... 7

7. Scutum with two prescutellar black spots; wing predominantly hyaline with dark patches (Fig. 56)..................... 8

- Scutum without prescutellar black spots; wing pattern dark fuscous to black with numerous hyaline spots and wedges (Figs 80–82)............................................................................................. 9

8. Wing with medial dark patch posterior to pterostigma reaching vein M 1 and with a hyaline spot in cell br (Fig. 56).................................................................................. Phorelliosoma hilaratum Hering

- Wing with medial dark patch posterior to pterostigma restricted to isolated spots in cell r 1 and along crossvein r-m................................................................................. Phorelliosoma ambitiosum Hering

9. Scutum predominantly yellow with black spots/markings (Figs 71, 72); wing dark brown with numerous hyaline spots (Figs 75, 76) ................................................................................................ 10

- Scutum red-brown or grey with or without black markings (Fig. 70); wing dark brown with hyaline wedges and spots (Figs 80–82)............................................................................................ 12

10. Cell r 1 with a single hyaline wedge-shaped marking (Fig. 39).......................... Erectovena desperata (Hering)

- Cell r 1 with two or more hyaline markings (Figs 75, 76)...................................................... 11

11. Cell r 4+5 of wing with a hyaline apical spot (Fig. 76); scutum yellow with dark brown to black spots, vittae absent (Fig. 72).............................................................................. Hexacinia radiosa (Rondani)

- Cell r 4+5 of wing with an oblique hyaline indentation (Fig. 75); scutum yellow with dark brown vittae (Fig. 71)........................................................................................ Ectopomyia baculigera Hardy

12. Wing with vein R 2+3 distinctly undulate (Fig. 82), especially in males; indentation in stigma fulvous and separated from hyaline indentation in cell r 1 by less than its own width or both indentations absent; head wider than high in males, as wide as long in females (Figs 65, 66)................................................................................. 13

- Wing with vein R 2+3 often not undulate (Figs, 78, 80, 81); if indentation in stigma fulvous then separated from hyaline indentation in cell r 1 by much more than its own width; head not sexually dimorphic in shape................................. 14

13 Wing with indentation in stigma fulvous and separated from hyaline indentation in cell r 1 by less than its own width (Fig. 82); eyes not distinctly stalked but head wider in males than females (Figs 65, 66).................... Themara yunnana Zia

- Wing without fulvous or hyaline indentations from costa in stigma and cell r 1, brown with two broad longitudinal yellow bands and a distinct oval white spot in cell r 4+5; eyes distinctly stalked by expansion of frons in males, not in females [Andaman Islands, India]................................................. Themara andamanensis Hancock & Whitmore

14. Anatergite with fine erect hairs (Fig. 73)........................................................ Ptilona van der Wulp. ............................................................................................. 15

- Anatergite smooth, without fine erect hairs (Fig. 74)................................................ Rioxoptilona Hendel. ............................................................................................ 17

15. Hyaline indentation at base of stigma not or only narrowly crossing vein R 2+3 as an elongate spot, hyaline indentation in cell m elongate and distinctly broadened posteriorly, and hyaline spot in cell dm transversely elongate, apical and indented or almost divided medially (Fig. 6).............................................................................. 16

- Hyaline indentation at base of stigma crossing vein R 2+3 as a quadrate spot and reaching vein R 4+5, hyaline indentation in cell m triangular and evenly broadening posteriorly, and hyaline spot in cell dm subcircular and anteroapical (Fig. 78)................................................................................................ P. confinis (Walker)

16. Hyaline spot in cell r 4+5 oval or rounded and not aligned with elongate hyaline spot in cell dm........... P. conformis Zia

- Hyaline spot in cell r 4+5 transversely elongate and aligned with elongate hyaline spot in cell dm (Fig. 6).................................................................................... P. confracta David & Hancock, sp. nov.

17. Wing dark brown, dimidiate without hyaline spots and markings............................... R. hemileina (Hering)

- Wing dark brown with hyaline indentations and spots (Figs 80, 81)............................................ 18

18. Hyaline indentation at base of pterostigma confined to stigma (Fig. 81)......................................... 19

- Hyaline indentation at base of pterostigma extending to cell r 1 or r 2+3 (Fig. 80).................................... 21

2+3

19. Vein R undulate................................................................................... 20

- Vein R 2+3 straight or nearly so (Fig. 81)................................................... R. vaga (Wiedemann)

20. Scutum red-brown without dark vittae..................................................... R. inermis (Hering)

- Scutum red-brown with dark longitudinal vittae......................................... R. formosana (Enderlein)

21. Cell br with a hyaline spot before r-m crossvein (Fig. 80)................................ R. dunlopi (van der Wulp)

- Cell br without a hyaline spot before r-m crossvein.......................................................... 22

22. Subscutellum and mediotergite yellow; male forefemur not densely setose....................... R. imparata (Hering)

- Subscutellum and mediotergite red-brown to blackish brown; male forefemur swollen and densely setose.................................................................................................... R. gravelyi (Munro)