So I posted my findings in my own journal. But, figured I'd post its own thread.
The optimal temperature for this species (Acromyrmex versicolor) is 73-75 fahrenheit. I think 72 is okay and maybe 71, but definitely not below that (or the fungus looks like its "melting"). I haven't gone past 75, but 76 will probably still be okay.
68 is definitely too cold, 78+ is definitely too hot. I didn't know why my fungus was dying off and all brown looking. But the other day my parents cleaned out the closet they are in and temperature dropped quite a bit, to 73 degrees (from 80). Literally the next day the fungus had completely recovered, it was that fast. Literally the next day the fungus was super healthy looking and had grown a lot. Now keeping them between 73-75, the fungus has nearly all grown back (in less than two weeks!) and the queen is very plump and healthy looking. Not to mention the fungus is super bright white and they workers have been able to start a lot of new fungus gardens too, that they couldn't do for months at 78-80 degrees.
Now, my colony DID grow really fast to begin with at 78-80. But, mid and long-term the fungus died off a lot at that (and the colony actually got stagnant at that temperature, and even declined just a bit after the initial growth boost). At 68 the fungus melts, and the colony becomes completely stagnant in growth.
Hope this helps others who plan to or keep Acromyrmex versicolor
