GW plastic zoanthropes and brood lord .

[LIOFO]

'These Genestealer cultists......where did you get the idea? I don't remember seeing it in a film, comic or in a book?'

From one of the early 90s Aliens comic books.

[Norton C Wongpower]

Link or it didn't happen.

[AndrewGPaul]

GW introduced "unbound" army option, you can mix all models/armies in all official games. So yes, you can mix ImpGuard and Tyranids. You could have done this before, just needed a bit of open mind gaming...

If you're going strictly by the rules, Tyranids and ... anyone else are "Come the Apocalypse" allies. This means that they can't deploy too close to each other, and don't count as friendly models for the purposes of psychic powers. You can sort of do a Cult list like that, but it'd handle a bit oddly.

The new Broodlord is on the cover of the new Tyranids painting guide, which just went up on the pre-orders section of the website, with a bigger photo than the one in the OP:

[wait, what?]

So it's pretty much the space hulk one then.