Rio's are from the Rio Grande river region. They are a bit more colorful and mines seems to like his temps a degree or two higher than any of my common RES did. Other than that they have the same basic care needs. They are also known as the Ornate RES. Not much on the web is said about them so I plan to do some studying and watching of his behavoir and habits when I return to the states.
I like the patterns on their shells. The pattern on Toku is getting more and more detailed as he grows. I'm very curious to see what he will look like in a few years.