Thank you very much for the restaurants which several of you took the time to suggest, but unfortunately none of them offer gluten-free pizzas. The only pizzeria with gluten-free offerings I know of in the New York area is Caffe Baldo in Wantagh (LI), which is pretty inaccessible to those of us without cars.
It is true that the restaurants recommended to me serve pizza made with spelt, which is often tolerated by those who are allergic to wheat. However, spelt is a distant relative of wheat and still contains gliadin (wheat gluten), which those of us with celiac disease cannot ingest. The cornmeal pizza could also be a possible alternative, but it's made with white flour as well as cornmeal. Those who are interested in learning more about the gluten-free diet should visit www.gluten.net.
I visited Cafe Viva at 179 Second Avenue, only to be disappointed to learn that I couldn't eat any of their pizza. Because of that experience, I called ahead to Cafe Viva on Broadway & 97th so as not to waste another trip. The woman I spoke with patiently verified with the pizza man the information I relayed above, and she said that their other locations don't offer anything different.
Thanks again for trying to help find a few more options.