I corresponded briefly with PHRatz about the differences between ornata and luteola. I'm still working on that, but I've posted two photos that show some differences between hatchlings of each subspecies. I'm been fascinated by this...I know it's probably boring for most of you. I apologize.
This ornata hatchling has bold markings both on the head and shell. You can see the genesis of only a few striations, bars, lines...whatever we are supposed to call them. This turtle is supposed to be related to wild turtles from Northeast Texas.
The luteola hatchling on the other post clearly has less bold markings on the shell and nearly none on the head (although some markings have developed since the photo was taken). Also, you can see the genesis of many more radiating lines, or striations, on the individual scutes. This turtle is supposed to be related to wild turtles from luteola's Westernmost range in Arizona.
I am working on a detailed report that I am going to try to get posted on chelonia.org. I don't know if this will even happen...I'm not aware of their selection process just yet. It will contain what I've gathered that most things I've read do not have...numerous observations from people who live or have lived within the turtles' ranges and have had significant field experience with the two subspecies.
For PHRAtz, the only person who expressed much interest, my contacts have basically summed your situation up as this; true luteola live in Mexico,Arizona, New Mexico, and a small portion of Western Texas. True ornata live in Central-to-Eastern Texas and states both North and East of Texas. In most of the other parts of Texas, the turtles are intergrades. Basically, there is no clear genetic or geographic boundary separating the two subspecies. This is a gross simplification, so please don't criticize too aggressively until I work out my entire report. I hope this helps. By the way, what does DH mean?
