homologue
From ZooTerms (Dictionary of Invertebrate Zoology)
common ancester of these taxa
homologue also homology (noun; Greek homologos, agreeing): 1. Features or organs in two or more taxa that can be traced back to the same (or an equivalent) feature in the
See also: analogy, heterology. 2. Basic similarity of organs or other structures that have had similar embryonic origin, but have developed in different ways for different purposes