Araneatrox and Rextelum DNAs have only ever been awarded as event prizes, and there's no way for players to create them, therefore no way for you to obtain those currently.
The other two are feasible, though I don't know if there are any in existence. There are certainly parts of it around, but perhaps not the full complement for creating a new DNA. In theory there might even be fully completed DNA of them, but if there are, they must have been lying around for quite a long time in someone's storage without ever being used, so I doubt it.