page_title: Species
section_title: Species description
hierarchical_section_title: Species / Taxonomy and naming / Species description
caption_attribution_description: English: The holotype of Lacerta plica Linnaeus, 1758, NRM 112. Note the tuft of spines on the anterior edge of the auditory meatus (A); the indistinct spots on the dorsum (B) and the double dewlap fold (C). Photo credit: Sven Kullander.
context_page_description: In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined.
  The total number of species is estimated to be between 8 and 8.7 million. However the vast majority of them are not studied or documented and it may take over 1000 years to fully catalogue them all.
  All species are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet. For example, Boa constrictor is one of four species of the genus Boa, with constrictor being the species’ epithet.
  While the definitions given above may seem adequate, when looked at more closely they represent problematic species concepts.
context_section_description: A species is given a taxonomic name when a type specimen is described formally, in a publication that assigns it a unique scientific name. The description typically provides means for identifying the new species, differentiating it from other previously described and related or confusable species and provides a validly published name (in botany) or an available name (in zoology) when the paper is accepted for publication. The type material is usually held in a permanent repository, often the research collection of a major museum or university, that allows independent verification and the means to compare specimens. Describers of new species are asked to choose names that, in the words of the International Code of Zoological Nomenclature, are "appropriate, compact, euphonious, memorable, and do not cause offence".
caption: The type specimen (holotype) of Lacerta plica, described by Linnaeus in 1758
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