is *A-PU supported by optiboot?
"Probably."
If you're asking about the "A" versions (atmega168-PU vs atmega168a-PU), those are normally indistinguishable (same behavior, same signature, etc - the bootloader and Arduino core SW can't even tell.) (Alas, not true of many "B" versions ("Atmel, you fool!"))
If you're asking about the part after the dash, that usually indicates package type, and the software doesn't care...