Beautiful - nice shrub!
I just got one just like this at a show, labelled P. gratrixianum, and did some research. I know it is all 'lumper/splitter' stuff and opinions but apparently:
P. gratrixianum has wide leaves and flowers on short stems.
P. christensonianum (P. gratrixianum v. christensonianum) has narrow upright leaves and tall flower stems. This is what I bought and what it appears in the OP)
P. daoense (P. gratrixianum v. daoense) has short stems and a dorsal that is predominantly white with spots and little green or pink.