I had the exact same crab in my tank. In fact, he may still be in there. I never could get a picture of him and he only came out of a hole at night. As soon as a light came on or there was movement, he went back in.
I never could get an ID on him because I couldn't get the picture, but that is definitely him.
Haven't seen him in his hole or elsewhere in a long time. That's fine with me! He had to eat something and I never figured out what it was....crabs, snails, fish???