The standard chromosome count for all galanthus species is 2n=24, only increasing in the case of polyploid forms (e.g. diploid elwesii has 2n = 24, tertraploid elwesi has 2n= 48) so it would not be possible to differentiate reginae-olgae and r-o vernalis on the basis of chromosome counts as both have the same number of chromosomes.
The only way is to use flow cytometry to find the amount of nuclear DNA, which does vary from one species to another. This is what Zonneveld did in the study suggested by Dimitri - The Systematic Value of Nuclear DNA Content in Galanthus. But r-o and r-o vernalis have very similar nuclear DNA content, so it would be virtually impossible to confirm their different identitites based on this, plus it's a complicated labortatory procedure.
DNA content studies do suggest (not surprisingly) that vernalis is likely to be an intermediate between nivalis and r-o.