This name is a synonym of Taraxacum pieninicum Pawł..
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record 167B5A35-DCAF-4FE7-A183-E08901B9AF9D) with original publication details: Domin in Preslia 13-15. 1935 250 1935.
This name record (from TICA) was not included in version 1 of The Plant List. It is possible the same name was included from a different data source, to check this you can search for Taraxacum hoppeanum in version 1 of The Plant List.