I've noticed that most zoos around the world never label their African lions any subspecies. Is this because the vast majority of them are hybrids, or because the zoos don't actually know their countries of ancestral origin?
Most are hybrids, but it's complicated since a recent taxonomic revision has shown that some lion "types" are the same subspecies (Asiatic lions and the now likely-extinct Barbary lions are both considered the same subspecies along with some other Northern African lion populations). It's pretty complicated, but I did find a studbook for P. leo krugeri in AZA zoos (though P. l. krugeri is now considered a part of P. l. melanochaita). Some zoos in Europe, as far as I know, keep Asiatic lions, and American zoos also formerly carried Asiatic lions (until they were phased out due to being mixed with African lions and poor record keeping).
Zootierliste lists Panthera leo bleyenberghi, Panthera leo somaliensis, and Panthera leo vernayi as subspecies in European zoos, but I have yet to see an American zoo that labels its lions this precisely.
AFAIK all pedigreed lions in American zoos originate from the South African population, regardless of whatever taxonomy is used.