Polygenesistically a word?

Heterogenic.

 

Biologically it would be analog.

Analog organs - same function, different origin - gill and lung

Homolog organs - different function, same origin - swim bladder and lung

 

Not sure what you are using it for, though. To be exact, heterogenic means something with a "mixed origin", as in, a baby which is a mix of two people's genes.

 

If your word isn't a real word. Use it.

If it is, don't and make up a new one.

That way when you use it, the others will not understand, but as long as you present it as truth, they will nod and be impressed by your leet brain power.

 

And then others will begin to use it until it is adopted by Merriam Webster's Dictionary, and then you can tell your kids that you made up a word in the dictionary, and then they can tell all their friends, "look what my dad did," and then they'll grow up and continue the legacy by creating a book entitled, "Wordsmithing to Impress," which will end up being a best-seller, and then they will be millionaires and buy you a bigger house, and a nice car, and perhaps a yacht with a bar inside... with 5 different kinds of beer... Or 6... oh, and a bottle or two of Glenlivit. And then you can grow old in happiness until it is discovered that the word you came up with actually existed, and was retired 300 years ago, and then no one else buys your kids books, because they know who their old pop is, and then you die of old age, and your sons move on to the cubicle life and walk around in a depressed state of mind, but you don't give a s**t because your dead.

 

This is how I would describe it. Typically, you don't hear the term heterogenic unless describing genes (heterogeneous vs. homogeneous for a given trait). It isn't wrong per se though.

You're trying to describe analogous features, which develop as a result of convergent evolution.