I answered you over on insects and bugs...lantana lace bug. They are sucking the juice from the cells of the leaves, along with the chlorophyll. An enzyme they inject to help digest also discolors the leaves.
There are poisons to control this insect, but they are also toxic to the butterflies that visit the lantana flowers. So, after fighting this for two years by cutting back the lantana and letting it regrow, only to have the lace bugs return, I pulled it.