Emma Roberts was transphobic to Angelica Ross on the set of ‘American Horror Story’ … so claims Angelica herself, who’s spilling even more alleged tea about her onetime costar.

The actress — who’s a trans woman — hopped on social media Tuesday to make the allegation … detailing what she says happened while they were filming ‘AHS: 1984’ back in 2018 when she was cast opposite ER … who was the lead that season.

Angelica says Emma misgendered her during an interaction with yet another costar, John Carroll Lynch, who told the “ladies” (meaning Angelica and Emma) to play nice between takes … this after Emma playfully complained AR was being mean.

Here’s what Angelica claims Emma said right after that … “Don’t you mean ‘lady.'” Apparently, she partially cloaked her face and walked away — leaving Angelica stunned.

After, Angelica says she never spoke another word to Emma when cameras weren’t rolling … but as far as why she didn’t report it — AR explains she felt she’d be retaliated against, claiming someone else on set who’d spoken up had been punished.

Lastly … Angelica alleges Emma was a major terror in general, pissing off the other actors and throwing her weight around in an insufferable way.