The real beauty about this hobby is that people can make their own models to fill gaps in their collection, whether that's conversions or fan sculpts. I recently received a fantastic model which evokes the genestealer-csith hybrid pictured in the Rogue Trader rulebook. It came from a fellow genestealer fan who has had it sculpted and a handful cast.
|Terrified crew-members attempt to gun down an escaped specimen they were transporting.
The leech-like csith are (according to Rogue Trader) the original symbiotic hosts of the genestealers, before the spread out into the galaxy and managed to breed with humans (whether or not this still holds true now that genestealers are part of the Tyranid family, I don't know!).
|A Ymgarl genestealer as pictured in Rogue Trader.