neomorph

from The Century Dictionary.

• noun In biology, a part or organ, or a modification of a part or organ, which has recently been generated or acquired.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Biol.) A structure, part, or organ developed independently, that is, not derived from a similar structure, part, or organ, in a preexisting form.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun genetics a gain of function mutation that causes novel gene function.