Answer: A patronymic
A patronymic is a component of a personal name that is based on the name of a male ancestor. This usually refers to someone's father or grandfather. If the ancestor that is included in the name is a female, this is called a matronymic. These words are used in order to establish a lineage. In this case, the phrase "born from Cadmus" establishes a common lineage among the people who are descendants of Cadmus.