I found another one of these queens in Trabuco Canyon, California on 6-28-2015. It was just wandering around on a dirt road at about 9:00 pm.
A day or two later it removed its wings and laid a small pile of eggs.
Pheidole vistana and P. desertorum look extremely similar, and are hard to tell apart. After doing a lot of reading, and studying pictures, I think I've figured out how to tell the queens apart. One of the most obvious characteristical differences between the workers is how P. desertorum has spines that look more similar to thorns and are directed posteriorly, while P. vistana has spines that are skinnier, like little spikes, and point upward slightly. Well I noticed on queens, it seems the spines actually curve inward a bit as you can see in the picture below. This also supports my suspicions about the two queens I found that night, because this one was a lot more yellowish, as P. vistana are.
Hopefully I have better luck with these this time.