A taxon (plural taxa) is an element of a taxonomy, e.g. in the scientific classification in biology. For example, in biology, the family Hominidae is one taxon, as is the genus Homo and the species Homo sapiens.

Taxa form a hierarchical scheme, each being broken down into subtaxa.

In traditional Linnaean taxonomy, taxa are ranked as follows, with some of the less widely used ranks indented:

Kingdom

Phylum (animals) or Division (plants)

Class

Order

Family

Tribe

Genus

Section

Series

Species

Variety

form

A prefix is used to indicate a ranking that falls between two taxa. The prefix super- indicates a rank above another, the prefix sub- indicates a rank below another, and the prefix infra- indicates a rank below sub-. For instance:

Superclass

Class

Subclass

Infraclass

It has become generally accepted that taxa should contain an ancestral form and all or some of its descendants, though the validity of the latter category is increasingly debated.

External link

• Rules of Biocode 1997