Coldscales! The largest tribe of alcepist and alraeon both! They're also the heaviest.
Oh, btw, I didn't draw it- but they can be more fluffy. I mention it in the picture, the fact that they do have a short, thick layer of fur over the scales (don't ask how that works. Idk)
That layer of fur can be thicker/longer and fluffier- more on the side of polar bears than seal fur. The downside is that the ones with longer fur have slightly more drag in the water when swimming. It doesn't affect it drastically though.
I also meant to make their claws a little more hooked, but idk, they look fine.
Also- heat resistance and cold resistance? The cold resistance is obvious- they live in a polar desert, of course they're fine with the cold. But heat resistance? Well, they radiate cold. My logic is that they can resist heat for some time before actually getting the problems of too much heat than the body can handle (heat stroke, basically). Them radiating cold is basically like sweat with humans. On a similar note, sunscales and warmscales have some cold resistance too, though warmscales can last longer in the cold than sunscales since they're more used to cold temps in the mountain peaks instead of the extreme dry heat of the desert. Rubblescales don't really get cold resistance or that much heat resistance, but humidity doesn't bother them too much. Idk if that makes sense :/
Other ref sheets below