infrataxa

Infrataxa is a term used in biological taxonomy to refer to a group of taxa that is below a higher, more inclusive rank and above the most specific ranks, such as species. It is not a formally defined or universally recognized rank in major nomenclatural codes (such as the ICZN for animals or the ICN for plants). Instead, infrataxa are used informally by some authors to describe lower-level groups collectively or to discuss a set of related lineages within a larger clade.

The exact meaning of infrataxa can vary between authors. Because it is not codified, it may be applied to different kinds of subordinate groups depending on the context, sometimes encompassing ranks such as infraorders, parvorders, subfamilies, or even certain clades above the genus level. In practice, infrataxa serve as a practical label in phylogenetic or comparative discussions when a researcher wants to refer to multiple related lineages without committing to a single, formal rank.

Etymologically, infrataxa derives from the Latin infra- meaning below and taxa meaning taxonomic groups. The lack of a standardized definition means usage is highly dependent on the author and the particular study.

Critically, supporters view infrataxa as a flexible tool for organizing and communicating about complex evolutionary relationships. Critics note that the term can introduce ambiguity and reduce comparability across works because it does not correspond to a fixed rank in the formal nomenclatural framework.

See also: Taxonomic rank, Infraorder, Superfamily, Subfamily, Clade.