Key to the South American Amblystira

1 Subcostal area with two rows of areolae ........................................................................ A. pensa Drake & Hambleton

- Subcostal area with three or more rows of areolae...................................................................................................... 2

2 Antennal segment I nearly three times the length of II......................................................................... A. solida Drake

- Antennal segment I two or less times the length of II .................................................................................................. 3

3 Head with occipital spines .......................................................................................................................................... 4

- Head without occipital spines ...................................................................................................................................... 8

4 Occipital spines short, not reaching middle of eye ...................................................................................................... 5

- Occipital spines long, at least reaching anterior margin of eye ................................................................................... 6

5 Hemelytra constricted; length approximately 3mm ................................................. A. peltogyne Drake & Hambleton

- Hemelytra not constricted, narrowing from the middle; length less than 2.5mm ................................. A. socia Drake

6 Paranota angulate opposite the humeral angles ................................................................ A. angella Drake & Ruhoff

- Paranota not angulate, scarcely developed or absent .................................................................................................. 7

7 Hemelytra entirely black except for a hyaline narrow space on the costal area .......................... A. niborskiana n. sp.

- Hemelytra black except for brown along the sutural area, the distal two thirds of the costal area and distal third of subcostal area ..................................................................................................................................... A. pallipes (Stål)

8 Hemelytra not constricted, narrowing from the middle............................................................................................... 9

- Hemelytra constricted ................................................................................................................................................ 10

9 Lateral carinae developed only on posterior process; hemelytra black except for the hyaline apical half and narrow space on the costal area ............................................................................................................ A. fuscitarsis Champion

- Lateral carinae develop on the posterior process and pronotal disc; hemelytra black except for a narrow hyaline space on the costal area ..................................................................................................................... A. silvicola Drake

10 Hemelytra strongly constricted, costal area uniseriate at it widest part ......................................... A. machalana Drake

- Hemelytra weakly constricted, costal area biseriate at it widest part ............................................... A. nyctalis Drake