Which name indicates a family branch or trait in Roman naming conventions?

In Roman naming conventions, the cognomen is specifically used to denote a family branch or a particular trait of a family. Roman names typically consist of three parts: the praenomen (the personal name), the nomen (which indicates the gens, or clan), and the cognomen, which can indicate a branch within that clan or a notable feature associated with the family. For instance, in the case of the famous general Scipio Africanus, "Africanus" serves as the cognomen, highlighting a significant achievement or characteristic of his family. This practice of using cognomina allowed Romans to differentiate between families that shared a nomen, providing a more specific identification within the broader clan structure.