when trying to argue such points, because common names are open to interpretation depending on where you live, who influenced you, etc. Example, in Europe, the common name "kingsnake" often refers to any kingsnake and milksnake. That is just a word, not proof that kings=milks are vice-versa.
Scientific names, while not necessarily perfect and are subject to change (sometimes drastically), are still your best bet for getting an idea of relationships among snakes.
A better question would be - What is the difference between getula (aka kingsnake) and triangulum (aka milksnake)? I don't even really know off the top of my head. Even that question though shows that I use "kingsnake" to mean getula. What about ruthveni, or mexicana, or zonata? See, even the word "kingsnake" as I use it shows my bias, because where I grew up catching kings, they were getula.
Yes, new methods e.g. DNA analysis will potentially change classifications just like what could happen someday with the Louisiana milksnake/kingsnake/mtn kingsnake (lol), but nevertheless, scientific names tell you more than the common names ever can.
Last point - although humans try and put snakes into neat little taxonomic boxes (and plastic boxes for that matter), nature doesn't care about that. Some snakes may not fit the bill exactly for what is a getula and what is a triangulum. Taxonomists may in that case give the snake its own species name I guess or may assign the snake to whatever it more closely resembles, or the scientists may argue over it.. but still, the goal is to tell us as best as they can how this snake relates to others, in a way better than just "kingsnake" or "milksnake."
BTW, does anyone know what the difference is between triangulum and getula?
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Mark