I have not seen Bostwana nils, do you have a photo?
these nils I have are from Kenya, they look much like ornatus but much smaler and have a dark toung.
I know of only 5 type of nils, ornatus, kenya, tanzania, egypt (blue nil) and the notorious comon nile from western Africa, perhaps the most nervous of all.
in regard to doreanus, the only way to tell them apart (jayapura vs bewanie) is when young, jayapura babies are orange and black while bewanies are grayish blue and brown, as adult both are similar in coloration and pateurning.
I only like the irian jaya type, they keep a rich coloration and deep blue tail even in old age.
Rgds
