A few days ago Tony D. raised the topic of how he looks for certain morphological characteristics to help identify pure thayeri. One characteristic that was not mentioned that I'd like to share is the double-striped ventral pattern. I'm going to go out on a limb and state that thayeri are the only Lampropeltis that possess this. If I am wrong, I know you guys will quickly correct me. But from my experience, I have never seen this in a pyro, ruthveni, greeri, getula, alterna, mex-mex, calligaster, or a L. triangulum. I have only seen this in Leonis thayeri morphs.
John L. mentioned, "All the wild type thayeri I have seen in person or in photos have grey faces......Black faced ones resemble Alterna, Pyro and Ruthveni." This is not a reliable method to ID thayeri. Attached is a macro of the head of the thayeri we found last summer in Iturbide, NL. It had a lot of black on its head and snout, with just a little red / peach
mottling.
Someone posted that iris color was one of the most important things to look at, and I fully agree. Garstka (1982) used iris color too as part of his diagnosis.
One more thing you can do is count ventral scales. Put the snake in a clear tube and start counting, or put it on a photocopier and make a copy. If you count between 190 - 211 you're in the ball park.
No doubt, with so much variation and unscrupulous breeders out there, trying to find pure thayeri these days can be tricky.
Gotta go clean cages....
Dan
