It is supposed to be a young Queen. This has been stated by Colin Strause on the boards. Like an in-between stage. Not yet fully grown. The host throat raping is just her way of reproducing before she is large enough to lay eggs, when she would become virtually immobile. The fact that her host was a Predator is just a coincidence, and should have nothing to do with how she is reproducing. She is not even close to being fully grown. Hypothetically, if it would survive it would grow far larger, gain the extra set of arms of a normal Queen, and grow an eggsack. In other words, it would eventually grow into a regular Queen, reproducing in a regular way as seen before, but just be a little bigger/uglier than a regular Queen. Nothing more or less. Aliens eggs spawned from her would still be born with a clean slate of pure Alien DNA. Her reproductive organs would then not contain any predator DNA. Otherwise all of the Aliens she is making in the movie would have predator features too, and clearly they do NOT, therefor the Aliens do not genetically dissolute over time, and it is NOT cumulative. This immature Queen’s, and any other Queen’s reproductive organs are pure Alien parts.