Genus (biology)

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Biological classification de

In biology (including virology ) the genus (also genus ) denotes a level within the hierarchy of biological systematics . It is above the species and below the family . A genus can contain a single species or any number of species. If it contains only one species, one speaks of a monotypic genus. In any case, a genus composed of multiple species is a group of species of common ancestry, separated from another species or from a group of species by a significant morphological distance. Willi Hennig specified this definition in 1966 in his work Phylogenetic Systematics to the effect that the species of one genus must be more closely related than with any other species of another genus.

All species within a genus always have a two-part (binary) name (the binomial ), which consists of the genus name and the species epithet . The genus name is always in the singular form and the species epithet repeats the gender of the genus name if it is an adjective. Abies alba (the silver fir ), for example, is one of approx. 51 species within the genus Abies ( firs ). The binary nomenclature of the species names goes back to Carl von Linné , who introduced them for plants in Species Plantarum in 1753 . In the 10th edition of Systema Naturae , published in 1758, binary names were given to animals as well as plants.

Subdivision of a genus

If a genus contains many species that can be classified according to different criteria, the following hierarchical ranks above the species rank are available:

  • Subgenus
  • section
  • Subsection
  • series
  • Sub-series

It is at the discretion of the descriptive biologist which of the ranks appears appropriate. Significant differences are usually expressed by subgenus (example: subgenus Solanum subg. Leptostemonum ); for inconspicuous variations, the section is used, e.g. B. Blackberries Rubus sect. Rubus . So there is no requirement that certain ranks should be used preferentially. However, the subsection (or sub-series) is only used if the section (or series) is also used. The name of the subgenus can be inserted in round brackets between the genus name and the specific epithet (example: blue-goose-clover Plebejus (Plebejus) argus and high-moor-blue plebejus (Vacciniina) optilete ). As a rule, names are used that have been given generic level in the past or still today by other authors. When subdividing into sub-genres, a sub-genus must bear the name of the genus. In this case, it should include a species or group of species that is particularly typical of the genus (example: Roman snail Helix (Helix) pomatia ).

The ranks below the sub-genus unit, i.e. section and series, are no longer permitted according to the current rules of nomenclature in the field of zoology, unlike in botany.

In virology , only the subgenus of these subdivisions is currently (as of March 2020) permitted.


  • Rüdiger Wehner, Walter Gehring: Zoology. Thieme, Stuttgart 1990, ISBN 3-13-367422-6 , p. 541 ff.

Individual evidence

  1. "a genus consists of one species, or a group of species of common ancestry, which differ in a pronounced manner from other groups of species and are separated from them by a decided morphological gap." Ernst Mayr : Taxonomic categories in fossil hominids. In: Cold Spring Harbor Symposia on Quantitative Biology 1950 , Volume 15, 1950, pp. 109-118, (here: p. 110), doi : 10.1101 / SQB.1950.015.01.013 .
  2. ^ Willi Hennig : Phylogenetic Systematics. University of Illinois Press, Urbana 1966.