I was recently trying to glean some perspective on the different species and subspecies of Thamnophis. I've learned that there are 13 different species and 40 subspecies native to North America. However; I haven't been able to find anything about Thamnophis native to Europe.
Does anybody have any basic information? The names of a couple garters would be really nice.

By the way, are garters found in any of the other continents: Africa, Australia...Asia? I've tried to google it but have always come up empty.

Any and all information is appreciated. Thank you.