I would think some kind of spider. Or mite. Have you tried soapy water or just plain? Try soapy in a spray bottle. Wet the plant well. Rinse after with plain water just to get the soap film off. It may be too late to save.
A couple of options if it doesn't look like it's coming back. Cut it back to the ground, or close, and see if it starts putting out new leaves or............
you could take it up and store the tuber till next year if you want to try it again. No guarantees it will work but if you want to go to the trouble.