I appriciate the lesson in speciation, however I don't think it's quote valid in the scope of this particular situation.
Regardless of species specifics, mollies are well known to hybridize amongst themselves and related livebearers (like guppies for example). It's also a little silly to say he is probably more closely related to a bronze Cory, since while the specifics of what kind of Molly may be different... It's still a livebearing Molly, and that will always be more close to "his own kind" than an egg laying bronze Corydora.
I should have been more specific when I described this confused male (who completely ignores all but the bronze Corys) the male is a orange DOMESTIC Sailfin. The majority of the female Mollies in his tank are White female domestic mollies, whom I should mention came from the same Asian supplier to my LFS on the same shipment. So I am fairly certain are the same DOMESTIC species of sail fin Molly as the confused male (they just happen to be a different color)
He shares his tank also with some wild collected Mollies from a local stream. Here in Hawaii the Molly is not a naturally occurring species, but rather an introduced invasive... So I dont feel bad at all for collecting them for a fish tank (since local fisherman collect them as crab bait) I don't think for a second they are pure species Sphenops either. Their coloration, while in much more subtle ways than domestics, is quite variable... And I am also pretty sure domestics have found their way to the stream to contribute to the gene pool. My calling them Sphenops was based on net info, as the males I collected of this kind have short dorsal fins like a female domestic Molly. They are also slightly larger with many females pushing 4-5 inches in length, and they also present a more slender profile than the domestic LFS purchased fish. Anyway... It is a wild collected short fined Molly of some kind that was a Hawaiian introduction (and I have heard Mollies -Sphenops is named in the historic literature- were introduced to aid in mosquito control here long ago.)
I like the answer that he is tagging the mollies when I'm not looking, but honestly, I never see him pay any attention to anything but the Corys! It's kind of peculiar to me.
I do know one of my other male Mollies has a very clear mate preference as well: in another tank, my male Marbled balloon sailfin lyretail male (Kinglet) has displayed a similar preference for mates, he obsessed over my black balloon females and attacks everything else! He also clearly hates regular body mollies of both genders, and will outright try to KILL normal body females, he only loves his black balloons...
I was wondering if anyone else had noticed they boys had a CLEAR preference of specific types... And I just thought it was strange the orange sailfin male prefers catfish...