P van Rijckevorsel schreef
Indeed there is no distinction in usage, otherwise there would be two or
more forms of epithets ("sinense" and 'sinanum'?!?) for popular geographical
names. As a rule there is one epithet for one geographical name.

+ + +
I should be more careful! China is indeed an exception:
"chinensis", "sinensis" and "sinicus"

PvR