Key to the Indo-Australian genera of Metopiinae

1. Face generally flat, with a large shield-shaped region bounded by a carina (Fig. 1a); mid tibia with one apical spur ............................................................................................... Metopius Panzer, 1806

– Face entirely convex, lacking a shield-shaped region bounded by a carina (Fig. 1b); number of mid tibial spurs variable ........................................................................................................................... 2

2. Metasomal tergites 3–5 without laterotergites (Fig. 2a) ................................................................... 3

– Metasomal tergites 3–5 with laterotergites (Fig. 2b) ........................................................................ 5

3. Areolet present (Fig. 3a); metasoma clavate, fifth and sixth segments much wider than preceding segments (Fig. 3b); mid tibia of male with one spur (Fig. 3c) .................. Acerataspis Uchida, 1934

– Areolet absent (Fig. 3d); metasoma parallel sided, fifth and sixth segments not wider than preceding segments (Fig. 3e); mid tibia of male with two spurs (Fig. 3f) ........................................................ 4

4. Mesopleuron with sulcus (Fig. 4a); lateral longitudinal carina only present on metasomal tergite 1 and base of second metasomal tergite (Fig. 4b); pronotum with dorsal longitudinal depression (Fig. 4c) ................................................................................................. Chorinaeus Holmgren, 1858

– Mesopleuron without sulcus (Fig. 4d); lateral longitudinal carina often present on metasomal tergites 1–3 (Fig. 4e); pronotum without dorsal longitudinal depression (Fig. 4f) ...... Trieces Townes, 1946

5. Interantennal process of face connected dorso-posteriorly to a high lamella separating the antennal sockets, this lamella with a vertical groove in it, just below the median ocellus (Fig. 5a) .............. 6

– Interantennal process of face not produced dorsally into a lamellate structure separating the antennal sockets, but often present as a low lamella posterior to antennal bases (Fig. 5b) ............................ 7

6. First metasomal segment petiolate anteriorly, its spiracle near or posterior to centre (Fig. 6a); sternite 1 long, reaching more than half of length of tergite (Fig. 6b); mandible with teeth subequal (Fig. 6c) ............................................................................................... Colpotrochia Holmgren, 1856

– First metasomal segment weakly to quite strongly (and evenly) tapered anteriorly, its spiracle near its anterior ⅓ (Fig. 6d); first metasomal sternite short, at most reaching about ⅓ of length of tergite (Fig. 6e); mandible with lower tooth much shorter than upper tooth (Fig. 6f) ................................... ........................................................................................................................ Triclistus Förster, 1869

7. Pronotum with upper part inflated, the pronotal lobes appear as large triangular structures in dorsal view (Fig. 7a); upper tooth of mandible broadly lobate, lower tooth acute and turned upwards (Fig. 7b); interantennal process separated from upper face by a sharp transverse carina (Fig. 7c) .... .................................................................................................. Stethoncus Townes & Townes, 1959

– Pronotum with upper part not exceptionally inflated (Fig. 7d); upper tooth of mandible triangular and acutely pointed, the lower tooth generally small and always straight (Fig. 7e); interantennal process never separated from upper face by a carina (Fig. 7f) ......................................................... 8

8. Areolet present (Fig. 8a) ................................................................................................................... 9

– Areolet absent (Fig. 8b) ...................................................................................................................11

9. Occipital carina entirely absent (Fig. 9a) ............................................ Carria Schmiedeknecht, 1924

– Occipital carina present at least laterally (Fig. 9b) ......................................................................... 10

10. Notaulus present (Fig. 10a); first metasomal tergite distinctly narrowing basally (Fig. 10b) ............ .................................................................................................................... Sciron Fitton, 1984 (part)

– Notaulus absent (Fig. 10c); first metasomal tergite broad basally (Fig. 10d) ..................................... .................................................................................................................... Seticornuta Morely, 1913

11. Mid tibia with outer spur distinctly shorter than inner spur (Fig. 11a) ........................................... 12

– Mid tibia with outer spur as long as inner spur (Fig. 11b) .............................................................. 13

12. Occiput vertical (Fig. 12a); posterior transverse carina of mesosternum convexly bulging medioposteriorly (Fig. 12b); first metasomal tergite with distinct lateromedian carina often extending 0.8× of tergite (Fig. 12c) .......................................................................... Hypsicera Latreille, 1829 (part)

– Occiput rounded to steeply declivous (Fig. 12d); posterior transverse carina of mesosternum straight medio-posteriorly (Fig. 12e); first metasomal tergite without or with lateromedian carina, if present extending 0.5 × of tergite (Fig. 12f) ....................................................... Exochus Gravenhorst, 1829

13. Notaulus present (Fig. 13a); first metasomal tergite narrowing basally (Fig. 13b) ............................ .................................................................................................................... Sciron Fitton, 1984 (part)

– Notaulus absent (Fig. 13c); first metasomal tergite not narrowing basally (Fig. 13d) ................... 14

14. Propodeum without traces of carina (Fig. 14a); first metasomal tergite without carina (Fig. 14b); epicnemial carina largely incomplete or absent dorsolaterally (Fig. 14c) ................ Soliga gen. nov.

– Propodeum with distinct carina (Fig. 14e); first metasomal tergite with longitudinal carina (Fig. 14f); epicnemial carina complete (Fig. 14d) ........................................................................................... 15

15. Propodeum without anterior transverse carina (Fig. 15a); at least anterior ⅓ of second metasomal tergite with distinct longitudinal carina (Fig. 15b) .......................... Drepanoctonus Pfankuch, 1911

– Propodeum with anterior transverse carina (Fig. 15c); second metasomal tergite without distinct longitudinal carina (Fig. 15d) ......................................................................................................... 16

16. Occiput vertical (Fig. 16a); metasomal tergite 2 with wide laterotergite (Fig. 16b) .......................... .......................................................................................................... Hypsicera Latreille, 1829 (part)

– Occiput roundly sloping (Fig. 16c); metasomal tergite 2 with narrow laterotergite (Fig. 16d) ......... ............................................................................................... Macromalon Townes & Townes, 1959