HI Andy.
I was thinking Solenopsis at first but the head does not look shiny enough to be a Solenopsis. The bottom ant appears to have well defined epinotal spines, leading me towards these being a Temnothorax. A side shot would help tremendously.

I can't see any propodeal spines, even on the bottom worker. But the slightly darkened hind part of the coxae III can easily be mistaken for such spines at a first glance.
Overall color is a bit dark for "standard" Pharao's ants, so it could be another species of Monomorium, a quite large genus as you know. But M. pharaonis is the most widespread in many tropical greenhouses worldwide.
Ironically, when I was a child, I mistook the various yellow or tan Temnothorax species for Pharao's ants, leading me to think this species was in fact quite widespread outside in my region!

Richard I believe you are right, the dull head thru me for a minute as well as what appeared to be the spine, my mistake. This is a group of ants that I have not had a lot of exposure to as they are not common in California and I missed the fact that these had been taken in a greenhouse.

I created a forum discussion to decide on placement. I don't know their status in Texas or the US as a whole. What confuses me is if I went to a Butterfly Exhibit in Philadelphia and they had Florida species on display would my images go in the guide? Maybe yes, but without collection data so it doesn't show on the map. But if these ants are found in the wild in Texas then they could have even come from the outside?

moved to Accidental Adventives. I wasn't sure if this should go in the guide or here? They are listed for the US, but it also sounds like they may also be transported in greenhouse plants. This seemed safest until a decision on proper placement is made.

Provided they are not (too early) discarded from there.
Because these two pics not only show an ant species new for BG, but are among the best quality pics of these small ants on the Web as a whole.