Diskutil can't find Core Storage Volumes
I was finally able to fix the problem:


boot into recovery
unmount all volumes (otherwise gpt will complain that the resource is busy)
use gpt to remove the partition (it had the HFS instead of the CoreStorage type)
also delete the partition from the MBR with fdisk (otherwise gpt will not allow you to add the partition).
finally use gpt to add the partition with the same values but as core storage (type 53746F72-6167-11AA-AA11-00306543ECAC)


Afterwards diskutil cs list showed the volumes again - disk utility repair did the rest. No data lost :)