Hi Matt. I think this is more likely to be just a darker form of D. nigromontana. It doesn't have the broad labellum sidelobes or the strong colour on the back of the dorsal sepal of semilunulata. It would be the first record of semilunulata from Black Mountain. The earlier (2001) records from BM and Aranda Bushland predate the description of nigromontana.