This thing oozes Lovecraft!
I especially like the swallow-disgorge-retreat tactic. A nice twist.
I can already picture the chaos a couple of these things would cause, and smell the fear from my players.
Using this beast in a murder-mystery type plot in a city with a sewer system would be interesting too.
As for the name, perhaps take a page from Cthulhu mythos and use some slurpy-sounding syllables combined with internal organs: Shoggophagus, Shubbach, Gastrogoth or The Sythestine Fluke.
Thanks Tom!