[9dev]

His name works like "Bostoner from Boston", so it was reasonable for him at the time to refer to himself as just Bostoner.

[srean]

I have always been intrigued by the similarity of Italian naming conventions and that of the Arabs and Persians.

Resident of, son of, father of, family of. Leonardo of Pisa of the family of Bonacci being another well known one.

I suppose it is not specific to those cultures and was a more widespread convention.