"Ok thanks i can see were i got mixed up. I thought Mangano was the one Maranzano madde boss after the Masseria killing. Who was boss after Mineo then?"

I really don´t know. There is a possibility that Scalise was made boss by Maranzano already right after Mineo was killed, perhaps on acting basis only. But considering the Family had split into two factions, Scalise must have been practically powerless at that time.
Another possibility is that the Family simply didn´t had a boss (right after the Mineo killing) and that a power vaccum occurred. I don´t think the two sides were able to name a boss. Who would have wanted the job at that time, considering the shooting came from all kinds of angles?