My rhynchostylis gigantea has lots of black spots on it. It also has an interesting looking semi see through yellowish spot with a pink ring around it. Finally, the leaves are yellow and shriveled.
Also, my renanthera has lost a half of a leaf and there looks like there is a little black streak on it. There are also some little indents in the leaves in places.
The Rynchostylis looks to be severely dehydrated causing the plant to be severly weakened. The black spots I am guessing are bacterial, try spraying with diluted Physan-20 or copper soap.