I'm pretty sure they have a specific name but as for now, I'm identifying it as famous Rex Begonia.
This one is stripped off all the pink/red hue tones and this the final appearance of what it will appear to be after many months.
I believe this is the main cultivar used to make newer hybrids that been mixed to give those variations. This particular Begonia is not that challenging to keep, unless it's not laced with some chemicals or sorts that will force the plant to stressed out and die within a short frame of time.
What I'm showcasing here are what's available in the local market around my region.
Begonia Common Names and Images
Here is the link where I had put together a list of all the begonias that I had come across. A database of all the different types & their characteristics. Please click on the link on the title above for the post.