Examples

The usual classifications of five species follow: the fruit fly so familiar in genetics laboratories (Drosophila melanogaster), humans (Homo sapiens), the peas used by Gregor Mendel in his discovery of genetics (Pisum sativum), the “fly agaric” mushroom Amanita muscaria, and the bacterium Escherichia coli. The eight major ranks are given in bold; a selection of minor ranks are given as well.

Table Notes:

• The ranks of higher taxa, especially intermediate ranks, are prone to revision as new information about relationships is discovered. For example, the traditional classification of primates (class Mammalia — subclass Theria — infraclass Eutheria — order Primates) has been modified by new classifications such as McKenna and Bell (class Mammalia — subclass Theriformes — infraclass Holotheria) with Theria and Eutheria assigned lower ranks between infraclass and the order Primates. See mammal classification for a discussion. These differences arise because there are only a small number of ranks available and a large number of branching points in the fossil record.

• Within species further units may be recognised. Animals may be classified into subspecies (for example, Homo sapiens sapiens, modern humans) or morphs (for example Corvus corax varius morpha leucophaeus, the Pied Raven). Plants may be classified into subspecies (for example, Pisum sativum subsp. sativum, the garden pea) or varieties (for example, Pisum sativum var. macrocarpon, snow pea), with cultivated plants getting a cultivar name (for example, Pisum sativum var. macrocarpon ‘Snowbird’). Bacteria may be classified by strains (for example Escherichia coli O157:H7, a strain that can cause food poisoning).

• A mnemonic for remembering the order of the taxa is: Do Koalas Prefer Chocolate Or Fruit, Generally Speaking? Other mnemonics are available at ^[4] and ^[5].

[edit] Terminations of names

Taxa above the genus level are often given names based on the type genus, with a standard termination. The terminations used in forming these names depend on the kingdom, and sometimes the phylum and class, as set out in the table below.

Table notes:

• In botany and mycology names at the rank of family and below are based on the name of a genus, sometimes called the type genus of that taxon, with a standard ending. For example, the rose family Rosaceae is named after the genus Rosa, with the standard ending “-aceae” for a family. Names above the rank of family are formed from a family name, or are descriptive (like Gymnospermae or Fungi).

• For animals, there are standard suffixes for taxa only up to the rank of superfamily.^[7]

• Forming a name based on a generic name may be not straightforward. For example, the Latin “homo” has the genitive “hominis“, thus the genus “Homo” (human) is in the Hominidae, not “Homidae”.

• The ranks of epifamily, infrafamily and infratribe (in animals) are used where the complexities of phyletic branching require finer-than-usual distinctions. Although they fall below the rank of superfamily, they are not regulated under the International Code of Zoological Nomenclature and hence do not have formal standard endings. The suffixes listed here are regular, but informal.^[8]