the appletonianum complex is one of the most actively speciating groups of paphs. All the "species" within this complex - appletonianum, hainanense, wolterianum, celebensis, robinsonii, etc probably represent members of a complex that will eventually become species due to geographic isolation or pollinator specificity or something along those lines. Thus there are many different interpretations of whether these things are true species. Perhaps this particular plant represents some intergrade of appletonianum with another member of this complex, but I'd feel very comfortable just calling it an appletonianum.
I have a number of members of this group and try to stay within "species" when making outcrossings, using plants with known provenance from direct importation or from sibs of imported species. For example, wolterianum 'Maybrook' is jungle collected plant from Cambodia imported in the mid 1970s. I don't have this specific clone (maybe someone does, maybe it is still alive I hope) but I have a bunch of selfings of it, which all display the same lack of distinct leaf mottling, etc. Same with robinsonii - I have two jungle-collected clones and have sibbed them. I love this group and have lots of files on them including most of the original descriptions and illustrations...if you want more specifics, fire away.