@Arico
Any news?
If the plants were mine, honestly, I'd likely have thrown them out...
I've had a run in with colocasia mosaic virus here... There are no confirmed reports of it in the states... But it's here!
I'm sure it's also in Europe, confirmed or not...
I'm not even 100% sure it can infect callas, but it can affect a broad range of aroids!
My screens not great, I really can't tell from the pics, but it has a bit of the look of it...
Colocasia mosaic with generally follow the viens of the leaf, with a distinct yellow feathering that runs out from the veins, the virus can also make small specks on the leaves, dead in the center, yellow and discolored around that, they grow and look like burn holes, it can be variable as all mosaic can, and will rarely affect the entire leaf.
As far as I know there is no way to eleminate the virus, there are chems that treat it, but the moment you stop treatment it will come right back!
It spreads through plants injury, any tiny knick is enough to let it in, insects are the main transmitters.
Fingers crossed for you!