Product of anagenesis or cladogenesis.

The "parent" of a descendant species would be an ancestral or ancestor species. See speciation

Note that things become complicated by the fact that "species" is both the singular and its own plural. Thus, we can certainly have more than one descendant species, both living simultaneously (products of cladogenesis) but also with one having given rise to the other or at least an ancestor of the other.

In addition, one can have multiple ancestral species, that is, a string of ancestral species extending all the way back to the .