I was reading it over with a few grad student friends of mine and we saw that Burbrink says E. guttata complex avoids mesic forest habitat, and thus the range maps have them not present around the mesic forests around the mississipi.
Ok, so why are they in the Everglades (though most of it isn't forest...)? Every single E. guttata I've found, both dead and alive, has been in a mesic forest. I realize that isn't a scientific argument, but its true. We know people who have found E. guttata in the areas that they supposedly don't exist in TX, OK, etc. also.