While it is true that no new chromosome is formed, the prokaryotic nucleoid comes with its own components. This nucleoid contains the genetic material for the prokaryote. The 'chromosome' of a prokaryote is called a genophore and that is the the actual dna codes. And, it is true, it is not a true chromosome in that it doesn't have the chromatin that a true chromosome would have. Still, it does get the job done.