Yes, they're German - Klemmsia. I bought these years ago, along with two extra-long ones.
Anyway, the head now looks like this:
And I'm trying to decide what to do with it: slap veneer either side or treat the fault line as a feature and just varnish it. Veneering could be a bit of a bore because of the curve up to the fretboard. The rest of the guitar is a somewhat scratchy mess, or rather I think it will be once I've got the grime off it, so the crack wouldn't be entirely out of keeping.
Anyway, spalted wood it wouldn't look all that different.