User blog comment:BannedLagiacrus/Discussion of the Week: Monster Mutations/@comment-4212769-20140111180744/@comment-4212769-20140111185619

Well, the ancestor simply wasn't that adapted to any environment, what allowed it to wander through different habitats before it reached their respective habitats. It's possible that there were or are Blangongas in the Forest and Hills, Volcano or Old Jungle, that weren't found yet or already went extinct because they were outcompeted while those two subspecies found an ecological niche to successfully survive there.