Key to species based on the worker caste (except for C. bakeri, which is incertae sedis.)

1 Propodeal spines developed and with pointed apices................................................................................................... 2

- Propodeal spines undeveloped and forming obtuse lobes ............................................................................................ 4

2 Antennal club 3-jointed. Pronotum raised steeply toward mesonotum in lateral view ................................ mucronata

- Antennal club 4-jointed. Pronotum raised moderately toward mesonotum in lateral view ......................................... 3

3 In lateral view, pronotum and mesonotum forming a single convexity, propodeum distinctly raised relative to prome- sonotum, metanotal groove deep ......................................................................................................................... vacca

- In lateral view, pronotum and mesonotum forming a single convexity, propodeum slightly raised relative to prome- sonotum, metanotal groove less deep .................................................................................................. yamanei sp. nov.

4 Dorsal median portion of head swollen ................................................................................................ tanakai sp. nov.

- Dorsal median portion of head not swollen .................................................................................................................. 5

5 Propodeal spiracle situated near the metapleural gland orifice, the distance between them about the same as the propodeal spiracle diameter (Fig. 4) ............................................................................................................................. 6

- Propodeal spiracle situated away from the metapleural gland orifice, the distance between them much greater than the propodeal spiracle diameter (Fig. 3) ....................................................................................................................... 9

6 Clypeus smooth and shining without longitudinal rugulae (Fig. 1) ..................................................................... inflata

- Clypeus striated with rugulae (Fig. 2) .......................................................................................................................... 7

7 Dorsal face of head strongly striated with abundant longitudinal rugulae. Scape not reaching posterior corner of head in large workers. Workers with pronounced size polymorphism .......................................................................... aurita

- Dorsal face of head not strongly striated with longitudinal rugulae. Scape reaching posterior corner of head. Workers monomorphic in size..................................................................................................................................................... 8

8 The posterior portion of pronotum with transverse rugulae in dorsal view (Fig. 6) .................................. physothorax

- The posterior portion of pronotum without distinct rugulae in dorsal view (Fig. 7) .......................................... onusta

9 Dorsal setae on posterior portion of fourth abdominal tergite directed medially (Fig. 8) ................................ difformis

- Dorsal setae on fourth abdominal tergite directed posteriorly (Fig. 9)....................................................................... 10

10 In lateral view, dorsal profile of promesonotum convex, propodeum distinctly raised relative to promesonotum, metanotal groove very deep ................................................................................................................................ sewardi

- In lateral view, dorsal profile of promesonotum convex, propodeum slightly raised relative to promesonotum, metanotal groove not so deep in dorsal median portion ................................................................................ ampullaris