neomorph
/ˈnɪə(ʊ)mɔːf/noun
1 Biology. An anatomical structure or feature that has arisen during phylogeny as a new development, rather than by derivation from earlier features; a structure that does not have a homologue in earlier forms.
2 Genetics. A mutant allele that produces an effect qualitatively different from that of the wild-type allele.
Origin
Late 19th century. From neo- + -morph. Compare slightly later neomorphism.