I opened mine at Banco Galicia located at at 1349 Av. Luis Maria Campos with only my passport. No problem. The banker's name is Nicolás.
And I only made the initial deposit for residency since Migraciónes didn't issue the residency visa / DNI after that initial deposit. They reissue the precarias without asking for proof of any subsequent deposits. So, I have no more of an idea what Migraciónes are doing than they do.
The Russians in my building are in the same situation. As are other foreigners with whom I speak. Nobody knows what Migraciónes are doing, if anything. In two weeks I'll submit my initial paperwork for citizenship. Good luck.