When these first appeared I thought it was spider mites but I couldn't see them. I then thought it was a virus. I sent pieces of the plant to the local University. It was cyclamen mites. They live in the new growth buds. They are very hard to kill and can only be seen with a strong hand lens or a microscope. They are sort of clear and colorless. I use Avid to get rid of them. (used Cinnamite, but it damaged the leaves and they(the leaves) fell off) The mites damage the new growth while it's still in the bud stage. This causes the leaves to become thick and hard. If you cut these off below any visible damage and spray with a good miticide, the new growth will be OK. If left alone, the leaves will turn a brownish color, then yellow then fall off. The buds will be damaged and usually not open, or will be severly distorted. These are the same mites that cause a disease called "The Blacks" on delphiniums where the new growth is dark and very distorted.
