Yeah, not still sure that they aren't just red sided. "One out of every 20 I caught was this red colour." But there's no mention if the rest of them possibly were just normal looking red sideds with just a few red spots on their sides, or if they lacked red entirely.

But seriously, if you look at that snake and imagine it without the red below the lateral, the color and distribution of red above the lateral just gives me every indication that this is just a local color morph of red sided. Just like about 1 in 20 of the concinnus' in a certain area of Oregon, lack red or orange and instead are anery with varying degrees of blue/green tint over all.