Poneriencat, I have my sights set on one species: Stigmatomma trigonignathum. I plan on taking a weekend camping trip to North Carolina where I believe it is distributed specifically to try to find this species and hopefully a colony, so if Lady Luck has been with me so far, perhaps she will smile on me for this species.
Good luck with that! Stigmatomma trigonagnathum is one of the rarest ants in existence, with the holotype discovered in 1948 and an accidental discovery in 2008. If you do manage to find a colony of this species, you will be one of the luckiest anters in existence!
There's actually quite a lot of "rarest ants in existence." Mostly cryptobiotic, like martialis, but also some above-ground genera.
That I know. There are quite a few ants that have been collected only once, unlike twice like Stigmatomma trigonignathum.
Fun fact: martialis was actually collected twice as well. They just lost the ant.
Yeah, I remember hearing about that. I've lost a few rare ants in the past myself. I lost a Strumigenys membranifera queen last year, which isn't too bad considering I now have a colony with at least three queens and then two separate queens, and also considering they're the most common Strumigenys in my area. Not too long after that I also lost the on Hypoponera ergatoid male I've ever seen.