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Taxonomic rank

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**Main Taxonomic Ranks:**
– Carl Linnaeus established a ranking scale with kingdom, class, order, genus, species.
– Nomenclature is regulated by nomenclature codes.
– Main taxonomic ranks include kingdom, phylum, class, order, family, genus, species.
– Domain, proposed by Carl Woese, is a fundamental rank.
Taxon is assigned a rank when given a formal name.

**Ranks in Zoology:**
– International Code of Zoological Nomenclature defines various taxonomic ranks.
– Prefix ‘infra’ indicates lower levels at or below family.
– Defined ranks include superfamily, family, subfamily, tribe, subtribe.
– Lower levels may be denoted using ‘infra’ before the rank.
– Species group can be both a category and an unofficial rank.

**Names of Zoological Taxa:**
Taxon above species has a scientific name (uninominal name).
– Species name is a binomial name (generic name + specific name).
– Subspecies name is a trinomial name (generic name + specific name + subspecific name).
– Definitions in ICN for cultivated plants include cultivar group, cultivar, grex.
– ICN rules apply primarily to ranks of family and below.

**Names of Botanical Taxa:**
Genus and above have a unitary botanical name.
– Species and above (below genus) have a binary botanical name.
– Ranks below species have a three-part botanical name.
– Hybrid names use ranks prefixed with ‘notho’ for hybrids.
Botanical nomenclature allows substitutions for outdated ranks.

**Terminations of names:**
– Taxa above the genus level use names based on the type genus.
– Standard ending -aceae for a family.
– Animals have standard suffixes up to superfamily rank.
– Uniform suffix -ida for orders.
– Ranks of epifamily, infrafamily, and infratribe used for finer distinctions.

**Additional Information:**
– Taxonomists can invent new ranks as needed.
– Ranks are assigned based on subjective dissimilarity.
– Higher taxonomic groupings reflect diversification events.
– Species is the most basic rank.
– Taxa without ranks cannot be named in traditional systems.

Taxonomic rank (Wikipedia)

In biology, taxonomic rank is the relative level of a group of organisms (a taxon) in an ancestral or hereditary hierarchy. A common system of biological classification (taxonomy) consists of species, genus, family, order, class, phylum, kingdom, and domain. While older approaches to taxonomic classification were phenomenological, forming groups on the basis of similarities in appearance, organic structure and behaviour, methods based on genetic analysis have opened the road to cladistics.

The major ranks: domain, kingdom, phylum, class, order, family, genus, and species, applied to the red fox, Vulpes vulpes.
The hierarchy of biological classification's eight major taxonomic ranks. Intermediate minor rankings are not shown.

A given rank subsumes less general categories under it, that is, more specific descriptions of life forms. Above it, each rank is classified within more general categories of organisms and groups of organisms related to each other through inheritance of traits or features from common ancestors. The rank of any species and the description of its genus is basic; which means that to identify a particular organism, it is usually not necessary to specify ranks other than these first two.

Consider a particular species, the red fox, Vulpes vulpes: the specific name or specific epithet vulpes (small v) identifies a particular species in the genus Vulpes (capital V) which comprises all the "true" foxes. Their close relatives are all in the family Canidae, which includes dogs, wolves, jackals, and all foxes; the next higher major rank, the order Carnivora, includes caniforms (bears, seals, weasels, skunks, raccoons and all those mentioned above), and feliforms (cats, civets, hyenas, mongooses). Carnivorans are one group of the hairy, warm-blooded, nursing members of the class Mammalia, which are classified among animals with notochords in the phylum Chordata, and with them among all animals in the kingdom Animalia. Finally, at the highest rank all of these are grouped together with all other organisms possessing cell nuclei in the domain Eukarya.

The International Code of Zoological Nomenclature defines rank as: "The level, for nomenclatural purposes, of a taxon in a taxonomic hierarchy (e.g. all families are for nomenclatural purposes at the same rank, which lies between superfamily and subfamily)."

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