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Trend curves of the rate of species description in zoolog

Recent comprehensive classifications[edit]

Partial classifications exist for many individual groups of organisms and are revised and replaced as new information becomes available; however, comprehensive treatments of most or all life are rarer; two recent examples are that of Adl et al., 2012,[63] which covers eukaryotes only with an emphasis on protists, and Ruggiero et al., 2015,[64] covering both eukaryotes and prokaryotes to the rank of Order, although both exclude fossil representatives.[64]


Biological taxonomy is a sub-discipline of biology, and is generally practiced by biologists known as “taxonomists”, though enthusiastic naturalists are also frequently involved in the publication of new taxa.[citation needed] Because taxonomy aims to describe and organize life, the work conducted by taxonomists is essential for the study of biodiversity and the resulting field of conservation biology.[65][66]

Classifying organisms[edit]

Main article: Taxonomic rank

Biological classification is a critical component of the taxonomic process. As a result, it informs the user as to what the relatives of the taxon are hypothesized to be. Biological classification uses taxonomic ranks, including among others (in order from most inclusive to least inclusive): DomainKingdomPhylumClassOrderFamilyGenusSpecies, and Strain.[67][Note 1]

Taxonomic descriptions[edit]

See also: Species description

Type specimen for Nepenthes smilesii, a tropical pitcher plant.

The “definition” of a taxon is encapsulated by its description or its diagnosis or by both combined. There are no set rules governing the definition of taxa, but the naming and publication of new taxa is governed by sets of rules.[8] In zoology, the nomenclature for the more commonly used ranks (superfamily to subspecies), is regulated by the International Code of Zoological Nomenclature(ICZN Code).[68] In the fields of botanyphycology, and mycology, the naming of taxa is governed by the International Code of Nomenclature for algae, fungi, and plants (ICN).[69]

The initial description of a taxon involves five main requirements:[70]

  1. The taxon must be given a name based on the 26 letters of the Latin alphabet (a binomial for new species, or uninomial for other ranks).
  2. The name must be unique (i.e. not a homonym).
  3. The description must be based on at least one name-bearing type specimen.
  4. It should include statements about appropriate attributes either to describe (define) the taxon or to differentiate it from other taxa (the diagnosis, ICZN Code, Article 13.1.1, ICN, Article 38). Both codes deliberately separate defining the content of a taxon (its circumscription) from defining its name.
  5. These first four requirements must be published in a work that is obtainable in numerous identical copies, as a permanent scientific record.