Theoretical Spell Crafting #2

I don't have a better source than that, I was just under the impression that heat species, like touch species, were very short range. In such a case they wouldn't naturally leave the magus's immediate vicinity, and cease being protected by the Parma Magica.

However, thinking about it, while heat is detected through the sense of touch it can be detected from several feet away from a large fire, so perhaps it would be seen as travelling far enough to leave their parma and be detected by either InIg or InIm.

In Hermetic Magic, at least, the feeling of heat falls under touch, and heat species under imaginem: Core Ruleboook page 156, Illusion of the Cool Flames.
But it could reasonably fall into the overlap with Ignem.