I do not think this P. viriosum and it is a bit late for them. Because of the labellum callus appearance and the lateral sepals I think this is P. innubum. Do you have a particular reason to consider this a P. viriosum?
I was noting length of leaf compared with flower head and general structure of flowers. Also growing on edge of alpine swamp. Ism certainly no expert. Will put up some photos from my camera rather than phone.