T.sumichrasti

[zooplan]

I'm willing to concede that I don't know anything about this species, but that's a very unusual pattern for a garter snake. It looks to me almost like a nerodia pattern.

Nerodia, Regina and Thamnophis are closely related to each other.
Once in a while the borders of the genii are objects of discussions.

[Stefan-A]

I believe Greg sent me a paper on that relationship. What I managed to gather from it by looking at the graphs in it, Nerodia is paraphyletic.