well being out of commission for a few days it looks like the answer is unravelled. however I would bet my bottom dollar (not that I have many above bottom) that it is not PEOY x sanderianum. aside from the shape which is all wrong, those petals look very pink at the end and you just don't get that from roths or sandy. those petals would be more typical of lowii, haynaldianum, or even appletonianum, but not from any bona fide coryo that I know of. and a few years ago a nursery out of Taiwan sold quite a few bogus flasks of "sandy" hybrids that bloomed out like jerry spence or something similar. if this were my plant, I would be questioning the source and asking for a refund.