A gorgeous variable dark species from Jubar, Vietnam.  It has only been available in cultivation for a few years but has not been commonly available.  It is unclear to me whether this is a described species or an unidentified plant with the species name, Jubar.  It was received as Begonia Jubar.  There is a described species with the name Begonia jubar, from Vietnam, but it is not clear to me whether the plant in question is the one I have, or another species from Jubar.  The paper on Researchgate is not publically available but I have requested the pdf from the authors (if you’ve never done this, they almost always send it you for free, definitely worthwhile) and hope to compare them soon.