Paph. mastersianum vs Paph. mohrianum
These two species are best distinguished when both plants are flowering:
First, here is some information:
Paph. mastersianum (REICHENBACH fil.) STONE
These plants are native to the islands of Ambon and Buro (Moluccas) and are said to be found at an altitude of 900-2000 meters.
Individual authors also report that the plants have been found on the island of Ceram. However, this location has not been confirmed.
Paph. mohrianum BRAEM
The Story of the Paph. mohrianum is more interesting. Some taxonomists refer to these plants as Paph. x bundtii (see Orchid Digest 1981). As parents, Paph. mastersianum and Paph. bullenianum var. celebesense, although no plants from the Paph. bullenianum group have ever been found.
Guido BRAEM then got the plants in 1995 as his own species Paph. mohrianum - Harald KOOPOWITZ named it in 2000 as Paph. mastersianum var. mohrianum.
Below I photographed both plants next to each other. So everyone can make their own judgement.
In any case, it is important that both “types” are propagated.
More photos can be found here: