No answer? Maybe because no one knows the cause. Most peculiar leaf damage, especially the mark on the left. Fungus usually shows up as black spots.

This post was edited by arthurm on Sat, Apr 13, 13 at 6:17

Likely mechanical damage, like hit a corner of the table or something.

There were not there when I bought them, and have been in a 30 gal open tank with uva/uvb lighting. They are on the underside of the leaf, so I not sure how it would have got hit. But when I first saw them they were smaller and I didn't really think too much of the spots. Now they are getting larger and seem to be spreading through to the front side. I have removed them from tank at this time. I have another orchid in the same tank but also different plant cuttings and would not want to get anything else sick if it is a virus/fungus.