Whats this
 

Got this on a Cattleya and we don't know what it is. Is it some kond of decise? The particalar plant is currently removed from any surrounding plants in case it is contagious.

To me this leaf looks like it is lack of some kinda of moisture, check on the root zone. Also catt leaves will do this after a blooming. But mine normal turn yellowie then drop off.
Check and make sure you plant isn't running to dry inbetween waterings.

I agree with Gloria,

It kinda looks like dehydration. Maybe from root loss? Also, I've noted that leaves will pimple sometimes when the plant is under great stress. This might account for the blackish marks. I'd check the roots to make sure there are enough to support the plant and watch it closely for a while. When a plant is sickly it's got a higher risk of attracting other problems.