Interesting Plant of Paph. glaucophyllum

This plant of Paph. glaucophyllum has flowers with an interesting pattern on its dorsal sepal.  Instead of the usual green patch with lines this one has scattered dots.  I grow my glaucophyllums and liemianums in the same medium and under the same conditions - bark, charcoal chips, limestone chips, clay pellets and some peat moss.

Close-up of the dorsal sepal