Key to adult males of Aposthonia Krauss, 1911

1. LC1 with two inner lobes; 10LP long, truncate, with a longitudinal groove, one side of distally curved to the left; 10 RP curved outward slightly terminally, truncate with two terminal teeth. (Fig. 4A)........................ A. minuscula (Enderlein)

- LC1 without two inner lobes (Figs. 4B–Y).................................................................. 2

2. LC1 distally expanded and lobed (Figs. 4B–K)............................................................... 3

- LC1 not abruptly lobed (Figs. 4L–Y)..................................................................... 12

3. LC1 slender basally, then broadly expanded dorso-mesad as angulate lobe; 10LP long, gradually arced leftward, evenly tapered to apex; 10 RP long, apex with outer hook and membranous inner margin (Fig. 4B)................... A. centralis (Davis)

- LC1 slightly incurved basally, then expanded at inner apex as lobe (Figs. 4C–K).................................... 4

4. LPPT sclerotized, apex with outer hook (Figs. 4C–H)......................................................... 5

- LPPT without outer hook or without LPPT (Figs. 4I –K)...................................................... 10

5. LPPT with inconspicuous outer hook; 10LP broad, tapered and arcuate caudally; 10 RP long, broad and gradually tapered to apex with outer hook (Fig. 4C)............................................................... A. davisi (Ross)

- LPPT with distinct outer hook (Figs. 4D–H)................................................................ 6

6. Eye very large; 10LP slender, broad rounded distally; 10 RP somewhat straight, very broad rounded apex with small spine on right side and mostly membranous inner margin (Fig. 4D).................................... A. mandibulata (Ross)

- Eyes small........................................................................................... 7

7. 10LP slender, bearing distally small hook directed forwards and downwards; 10 RP long, slightly tapered to tip with small outer hook and membranous inner margin (Fig. 4E)......................................... A. subclavata (Davis)

- 10LP without distal small hook (Figs. 4F–H)................................................................ 8

8. 10LP broad, tapered and arcuate caudally; 10 RP long, membranous inner margin long with distinct subapical tooth on outer side (Fig. 4F)........................................................................... A. brunnea (Ross)

- 10LP narrow (Figs. 4G, H).............................................................................. 9

9. 10LP slender, narrowly rounded distally; 10 RP elongated, narrow, membranous inner margin with small outer hook at apex (Fig. 4G)........................................................................... A. borneensis (Hagen)

- 10LP gradually and evenly narrowed and rounded terminally; 10 RP somewhat straight, apex with small outer hook and lengthy membranous inner margin (Fig. 4H).................................................. A. maritima (Ross)

10. 10 LP long, broad, gradually arced leftwards, evenly tapered and rounded terminally; 10 RP somewhat straight, rounded apex with outer spine and membranous inner margin (Fig. 4I)........................................... A. aurea (Ross)

- 10LP narrow (Figs. 4J, K).............................................................................. 11

11. 10LP long, narrow gradually arced leftwards, evenly tapered to apex; 10 RP long, lengthy membranous inner margin, apex with two small component teeth (Fig. 4J)........................................................ A. albertisi (Navás)

- 10 LP distinctive, basally rather irregular, distally sharply narrowed and curved downwards and bearing distally acute hook directed upwards; 10 RP long, broad, gradually narrowed caudally with small outer hook and mostly membranous inner margin, without LPPT (Fig. 4K)................................................................ A. remota (Davis)

12. LC1 subcylindrical (Figs. 4L–N)......................................................................... 13

- LC1 gradually expanded but not lobed (Figs. 4O–Y)......................................................... 15

13. LPPT sclerotized, apex with outer hook; 10LP long and abruptly tapered caudally; 10 RP long, gradually tapered to narrowly rounded apex, subterminally with very small but distinct outer process (Fig. 4L)....... A. himalayensi s (Kapur & Kripalanti)

- LPPT without outer hook (Figs. 4M, N)................................................................... 14

14. 10LP long, curved and slightly tapered leftward, apex with turned up outer hook; 10 RP long, broad, rather straight, side caudally convergent to obtuse apex and a small membranous inner margin (Fig. 4M)...................... A. oculata (Ross)

- 10LP long, not curved, narrow and evenly tapered to apex; 10 RP elongated, narrow, membranous inner side with small outer hook at tip (Fig. 4N)...................................................................... A. problita sp. n.

15. 10 LP with terminal hook (Figs. 4O–Q)................................................................... 16

- 10 LP without terminal hook (Figs. 4R–Y)................................................................. 18

16. 10 LP broad, apex tapered with anchor-like hook; 10 RP slender with hooked apex; LC1 strongly produced inwards into a transverse lobe reaching almost to the middle line (Fig. 4O)....................................... .. A. glauerti (Tillyard)

- 10LP narrow (Figs. 4P, Q).............................................................................. 17

17. LC1 distally curved inwards to tapered obtuse beak; 10LP slender, curving slightly to the left and bearing distally small hook directed forwards and downwards; 10 RP elongated, tapering distally but ending smoothly, and with lengthy membranous inner margin (Fig. 4P)...................................................................... A. gurneyi (Froggatt)

- LC1 with blunt subterminal inward projection, inner margin basal to projection slightly and smoothly concave; 10LP long, slightly tapered leftward, apex with slender acute terminally spine directed forward and to the left; 10 RP long, lengthy membranous inner margin, apex with outer hook (Fig. 4Q)......................................... A. spinulosa (Davis)

18. Under 10 LP, hooked LPPT present (Figs. 4R–T)........................................................... 19

- Under 10 LP, hooked LPPT absent (Figs. 4U–Y)............................................................ 21

19. LPPT sclerotized, apex with inconspicuous outer hook, 10LP long, gradually... arced leftward, evenly tapered to apex; 10 RP elongated, rounded apex with small spine on right side and slightly membranous inner side. (Fig. 4R)… A. hollandia ..(Ross)

- LPPT sclerotized, apex with outer hook (Figs. 4S–T)........................................................ 20

20. LC1 very broad, slightly expanded at basal third, then apically attenuated and curved caudally; 10LP broad, round distally, apex truncate with a single serration at outer angle; 10 RP long, broad and gradually tapered to apex and lengthy membranous inner margin (Fig. 4S)..................................................................... A. micronesiae (Ross) .

- LC1 inwardly lobed distally, 10LP broad, tapered and arcuate caudally; 10 RP long, lengthy membranous inner margin, apex with small outer hook (Fig. 4T)............................................................. A. oceania (Ross)

21. 10LP with lateral lobe (Figs. 4U–V)...................................................................... 22

- 10LP without lateral lobe (Figs. 4W–Y)................................................................... 23

22. 10LP forcipate, right-hand lobe heavily sclerotized, curved to the left and acute terminally, left-hand lobe more dorsal in position, flat, less heavily clavate on the concave inner side. 10 RP elongated, gradually narrowed caudally with small outer hook; LC1 terminally incurved to form spatulate process (Fig. 4U)...................................... A. tillyardi (Davis)

- 10LP terminally tapering to point, slight incurved with subterminal flat, acute projection directed to the left; 10 RP slender, terminally tapered to obtuse apex and lengthy membranous inner margin; LC1 clavate, produced inwards subterminally (Fig. 4V).................................................................................. A. approximans (Davis)

23. LC1 strongly excavated on inner side in basal half (Figs. 4X –Y)................................................ 24

- LC1 not strongly excavated on inner side in basal half; 10LP long, gradually arced leftward, evenly tapered to apex; 10 RP long, membranous inner margin long, apex with outer hook (Fig. 4W)............................... A. japonica (Okajima)

24. LC1 produced inwards into strong beak; 10 LP slender, evenly narrowed to simple round tip; 10 RP greatly elongated, membranous inner margin with outer hook (Fig. 4X)................................................... A. indica (Davis)

- LC1 not produced inward into strong beak; LP slender, evenly narrowed to simple round tip; 10 RP greatly elongated, membranous inner margin with hooked apex (Fig. 4Y)............................................ A. ceylonica (Enderlein)