[Aloisius]

I don't see an st ligature. I forced ligatures on and off on the Apple supplied font and see none (not even for th or fi):

http://i.imgur.com/O0jYcKF.png

[gpvos]

Oops, sorry. It seems the font got blocked somehow, and one of my fallback fonts apparently has them. Sorry again, that was a useless comment of mine.