Why is イタリア and not イタリャ?


I'm Italian and while I was studying katakana words such as イタリア I didn't
understand why, even though in Japanese there is the specific syllable "rya"
(リャ), it's not used in the word イタリア and instead the combination of syllables
"ri" and "a"(リア) is used as it has the same sound. So why is イタリア and not
イタリャ?




I'm not an expert, but I think this would be because イタリャ would be based on
some hypothetical word *Itaglia.




I'm not an expert, but I think this would be because イタリャ would be based on
some hypothetical word *Itaglia.

