The genus (even genus ) is a rank in the hierarchy of biological systematics. It stands above the type and below the family. A genus may contain a single kind or any number of ways; it contains only one type, it is considered monotypic.
In any case, it is in a genre that consists of several types to a group of species common descent, which is separated from another species or group of species with a distinct morphological distance. Willi Hennig clarified this definition in 1966 in his book Phylogenetic Systematics to the effect that the species of a genus would have to be closely related to each other than with any other species from a different genus.
All species within a genus always have a two-part ( binary ) name ( the binomials ), which consists of the genus name and the species epithet. Abies alba ( silver fir ) as is one of about 51 species within the genus Abies ( fir ). The binary nomenclature the species name goes back to Carl Linnaeus, who introduced it in Species Plantarum for plant 1753. In the 1758 edition of Systema Naturae, published 10 binary names are given next to the plants for the animals.
Structuring of a genus
If a genus contains many species that can be sorted according to different criteria, the following hierarchical ranks are available:
It is within the discretion of the descriptive biologists, which seems appropriate to the ranks. Significant differences are usually expressed by subgenera; the inconspicuous variations rather the section is used. So there is no requirement that certain ranks are preferred to use. However, the sub-section ( or sub- series) is only needed if the section (or series) is used. The name of the subgenus can be inserted with a round parentheses between genus and species names (example: Silver-studded Bluebird Plebejus ( Plebejus ) argus and high moor 's Blue Plebejus ( Vacciniina ) optilete ). As a rule, names are used, which are granted in the past or still in use by other authors genus level. The subdivision into subgenera subgenus must bear the name of the genus. You should in this case include a species or group of species, which is especially typical for the genus (example: snail Helix (Helix ) pomatia).
The ranks below the unit subgenus, ie section and series, are according to the current rules of nomenclature in the field of zoology, unlike in botany, no longer permitted.