myrmicaria
One of the oddest results from the Ant Tree of Life phylogeny was the recovery of a close relationship between Monomorium and Myrmicaria, two rather different looking ants.
But it all seems a little more plausible when looking at the Monomorium infuscum specimen recently uploaded to antweb. I know this is just a gut impression, but still. If M. infuscum sprouted spines and lost a few antennal segments it'd be most of the way there.