Sunday, December 9, 2007

In zoology, a taxon is usually assigned to a rank in a hierarchy. The ICZN divides names in "family-group names", "genus group-names" and "species-group names". The ICZN explicitly mentions:
- - - superfamily
- - - subfamily
- - - tribe
- - - subtribe
- - - subgenus
- - - subspecies
The rules in the 'Code' of the ICZN apply to the ranks of superfamily to subspecies, and only to some extent to those above the rank of superfamily. In the "genus group" and "species group" no further ranks are allowed. Among zoologists, additional ranks such as species group, species subgroup, species complex and superspecies are sometimes used for convenience as extra, but unofficial, ranks between the subgenus and species levels in taxa with many species (e.g. the genus Drosophila).
Ranks of taxa at lower levels may be denoted in their groups by adding the prefix "infra," meaning lower, to the rank. For example infraspecies or infrasubspecies. Infraspecific taxa then include all divisions of the species into subspecies or lower taxa.

Rank (zoology) Names of zoological taxa

a taxon above the rank of species gets a scientific name in one part (a uninominal name)
a species (a taxon at the rank of species) gets a name composed of two names (a binominal name or binomen : generic name + specific name; for example Panthera leo)
a subspecies (a taxon at the rank of subspecies) gets a name composed of three names (a trinominal name or trinomen : generic name + specific name + subspecific name; for example Felis silvestris catus, the house cat). As there is only one rank below that of species no connecting term to indicate rank is used.

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