If your opponent turtles, GMA member Ricardo Cavalcanti has a couple ways for you to submit regardless. Sometimes dealing with an opponent who chooses to stay on all fours can give you many options. While you can take the back or roll them to side control, perhaps, getting a choke sounds like a good avenue.
Check out this triangle variation from Cavalcanti:
Check out more videos from Ricardo Cavalanti and his academy, GMA Carlson Gracie Training Center – Cavalcanti BJJ in Las Vegas, NV by visiting www.rcjiujitsu.com