When I first observed Prolasius through my viewfinder, I was surprised at just how… average it looked. It was small, but not excessively. Its limbs were of medium length. It was brown. It had few salient features. It was, in fact, just about as plain as an ant can be.
Perfect, in other words, for an identification challenge!
Sadly, MarekB saw right through my ploy and posted the correct answer within minutes. So. Ten points to Marek.
Incidentally, Prolasius is one of those ants with hardly any technical literature. To be an average-looking ant in a country full of bull ants and other oddities is to fly under the radar of myrmecology. The result is we know little about it.