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Well, whatever we call it, here are some from Australia:

According to the Ants of Australia page, Carebara ranges 9 to 11 segments while Pheidologeton has 11.

Pheidole has 12, if I remember correctly.

There are two recent studies that use DNA sequence data from several genes to look at the relatioships of ant genera, and neither of them put Pheidole close to Carebara or Pheidologeton. Pheidole appears to be related to things like attines, dacetines, and Wasmannia, while Carebara is closer to Leptothorax and Myrmecina. However, it's long been known that the major caste in those groups is a case of evolutionary convergence, as there are some fundamental morphological differences in the way they are put together. As it is, worker dimorphism is known to evolve in ants with some frequency.

Sources:
Brady et al (2006) Evaluating alternative hypotheses for the early evolution and diversification of ants. PNAS. www.pnas.org/cgi/doi/10.1073/pnas.0605858103

Moreau, C.S., Bell, C.D., Vila, R., Archibald, S.B., & Pierce, N.P. (2006). Phylogeny of the Ants: Diversification in the Age of Angiosperms. Science 312 (5770): 101-104.

{{Fixed spelling of Myrmecina. (Too many different versions of the root 'myrm" in ant taxonomy for anyone other those with photographic spelling memory, eh?) -- Dr. Ant}}

If you go to this site and scroll down, you'll get a discussion on the varying numbers of antennal segments in Acropyga species:

Acropyga of Costa Rica

As you can see, some ants can even have differing numbers on their left versus their right antenna. However, such variation is extreme: most individuals of most ant genera have the same number of segments.