Paracorus

Paracorus is a proposed, though not formally recognized, term in cladistics (a system of biological taxonomy that defines taxa uniquely by shared ancestry). It describes a group of organisms that are paraphyletic with respect to another, more inclusive group but monophyletic within themselves.

Specifically, a paracorus represents a subset of a paraphyletic group. A paraphyletic group contains a common ancestor and some, but not all, of its descendants. In contrast, a monophyletic group contains a common ancestor and all of its descendants.

Therefore, a paracorus is distinct from both monophyletic and paraphyletic groups. It represents a grouping where a subset of a paraphyletic group forms a monophyletic clade.

The utility and recognition of the term "paracorus" are debated. Some argue it provides a more nuanced understanding of evolutionary relationships when dealing with paraphyletic groups. Others contend that the term is unnecessary and potentially confusing, as the concept can be adequately described using the terms monophyly and paraphyly within a cladistic framework. The term is not widely used in the scientific literature.