Valid name of the plant Jostaberry?

Jostaberry!
It is a crossed fruit (Ribes x nidigrolaria) - but the right Latin name?

 

I don't know the plant but you should have at least part of the Latin names. Hybrid crosses don't get a binomial Latin name. The "x' indicates a hybrid cross.

 

You have the correct name:
Ribes ×nidigrolaria Rud. Bauer & A. Bauer

It is a cross of R. nigrum × R. divaricatum × R. nigrum × R. divaricatum × R. uva-crispa

http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?318352

http://en.wikipedia.org/wiki/Jostaberry