It's as likely a natural hybrid as a new species. All natural corydoras hybrids I have encounted have only been small numbers of fish 1 or 2 individuals. If this appears in serious numbers, then it's more likely a new species. This is, of course, assuming it is a natural hybrid and not being crossed in South America...
I would tend to agree with Jools. I believe this looks a lot like a fish I've seen listed that's being hybridized intentionally in South America. If it is that fish, it's a hybrid between virginiae and adolfoi.
Larry Vires
Impossible only means that somebody hasn't done it correctly yet.