That's specially easy to note in black cats, they really seems a bit bald.
I do not think that's an evolved adaptive trait, anyway. Maybe it just doesn't affect for bad (thus being selected more "haired" cats) and is at the same time a unavoidable result of the body development....
About cat's taxonomy, the mountain lion is in the genus Felis only in some old classifications, where all (or at least the extant or recently extinct ones) cats were divided in only three genus (genuses? Geni?) In Felis, all the "small" cats, except cheetah, that was the only in its own genus (Acinonyx), from the smallest, whatever it may be, to the biggest of the small ones (the mountain lion) , and in Panthera, all the big cats, leopard, jaguar, lion and tiger. But there are classifications that split Felis in some other groups, the mountain lion is Puma concolor, for example, rather than Felis concolor.