I have tried to check it against the pictures at http://www.begonias.org/greenhouse/imagelisting.htm and it looks like 10 of them. I don't really know what to look for (some pictures on the website is not very clear though). In a book, there's a picture of Begonia maculata that looks like my plant, but then when I look at the maculata in the above website, it looks quite different.
B. maculata seems to have a more pointed leaf than yours. With so many versions of what is commonly called an angle-wing begonia. "Angel Wing" begonias are hybrids Begonia's which I read are a cross between Begonia aconitifolia and B. coccinea, so it can be hard to come up with a name other than common. I have a spotted angel-wing begonia called, (My specail Angel) Other than that, I don't know it by any other name. Have you looked at Begonia coccinea?
