General principles for formal taxonomic names

This section covers:

International standards and resources

A number of databases of life on Earth are available online. The Catalogue of Life, maintained by the United States–based Integrated Taxonomic Information System, provides authoritative taxonomic information on plants, animals, fungi and microbes of the world.

The Global Biodiversity Information Facility (GBIF) is an international open-data infrastructure, funded by governments.

Australian conventions and resources

In Australia, the Atlas of living Australia is a node of GBIF. 


Note: More detailed standards and resources are provided in the specific sections for types of organisms (eg plants, bacteria, animals).

Caution! Authors of specialist publications might follow particular conventions – check with the author or publisher of your document.

Taxonomic ranks

A consistent ranking system for naming organisms was first developed by Linnaeus in the early 18th century. Organisms were initially classified into 2 kingdoms, but recent schemes propose 5 kingdoms. The major taxonomic ranks are as follows (with the taxonomic classification for the red kangaroo given as an example):

  • kingdom (eg Animalia)
  • division or phylum (eg Chordata)
  • class (eg Mammalia)
  • order (eg Diprotodontia)
  • family (eg Macropodidae)
  • genus (eg Macropus)
  • species (eg Macropus rufus – red kangaroo). 

Taxonomic ranks do not have an initial capital when used in text:

Below the rank of kingdom, the next taxonomic rank for plants is division.

The names of bacterial taxa (kingdom, divisions, phyla, classes, orders, species and subspecies) are …

Did you know? A taxon (plural: taxa) is an item – a grouping of related entities – within any rank. For example, Myrtaceae is a taxon at the family level, and Eucalyptus saligna is a taxon at the species level.

Unless you are editing a specialist text, the taxonomic ranks most commonly encountered are order, family, genus and species. No rank above order is used for viruses. Taxonomic groupings below species level (eg subspecies) exist for all major groups of organisms.

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Higher taxonomic groups

Names of higher taxonomic groups (family and above) generally have an initial capital but no italics:

Mammalia     Marsupialia     Rodentia     Muridae     Myrtaceae

However, there are exceptions; see Bacterial names and Virus names.

The name of the rank (eg family, order) takes lower case in text:

The family Myrtaceae consists of ...

In one classification system, superorder Glires includes the orders Lagomorpha ...

but an initial capital in a taxonomic listing:

Superorder Glires
                Order Lagomorpha

                Order Rodentia

The names of families and higher-order taxa are treated as plural:

The Epacridaceae are endemic to Australia 

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Latin species names

Each species, which is considered to be distinct from other related organisms, has a unique Latin name that consists of 2 parts (called a binomial): the genus name and the species name. There might also be a subspecies name, resulting in a trinomial. The spelling of Latin binomials and trinomials should be checked (see the subsections on plants, animals and so on for authoritative sources).

Caution! Note that different rules apply when referring to bacterial serovars; see Bacterial names. Virus names also follow different rules; see Virus names.

Use italics for genus, species and subspecies names, with an initial capital for the genus name and lower case for the species and subspecies names; the rank of a trinomial is in roman:

Mus musculus     Eucalyptus globulus     Eucalyptus globulus var. bicostata     Salmonella enterica     Homo sapiens sapiens

Species names are always singular:

Cyathodes platystoma is restricted to wet eucalypt forests   not   Cyathodes platystoma are restricted to wet eucalypt forests

as are genus names:

Cyathodes is endemic to Tasmania.

Do not use commas when the name is defining:

The species Eucalyptus globulus is the only member of the genus that ...    not   The species, Eucalyptus globulus, is the only member of the genus that ...

Abbreviating the genus name

After the genus and species names have been given in full at the first mention, the genus name can be abbreviated to the first letter followed by a full stop. Include a space between the stop and the species name; use a nonbreaking space to avoid the name splitting over a line:

M. musculus     E. globulus

How to insert a nonbreaking space:
Use Ctrl+Shift+Space (Windows), or Option+Space (Mac).

Did you know? A nonbreaking space appears in the text like a ‘degree’ symbol: °.

Ensure that there is no confusion with other names in use in the text:

The gram-positive bacterium Streptococcus pyogenes causes rheumatic fever. Recently, scientists in the United States sequenced the S. pyogenes genome.

The biting midge Culicoides brevitarsis is the main vector of 2 viruses in Australia ... The vector is believed to be the mosquito Culex annulirostris. This mosquito is less susceptible to climatic extremes than C. brevitarsis and often has a wider distribution.

[There is no ambiguity about which genus the C. in C. brevitarsis is referring to.]

Specimens from a range of taxa were collected, including Olearia hookeri, Ozothamnus hookeri, Monotoca glauca and Trochocarpa disticha. Of these species, only Ozothamnus hookeri is found in montane habitats. Olearia hookeri occurs in dry areas of the east coast, and M. glauca and T. disticha are wet forest species.

[The generic names Olearia and Ozothamnus need to be put in full because O. hookeri could refer to either genus.]

Do not use abbreviations comprising 2 or more letter to distinguish genera with the same initial (eg St and Sa for Streptococcus and Salmonella, respectively), because these abbreviations are not standardised, and such use can lead to inconsistencies between documents. If there is any confusion, write out the genus name in full at each mention.

The styles of some journals and organisations allow a genus name to be abbreviated at the beginning of a paragraph or sentence, whereas others do not, so check the house style that you are writing or editing for.

Give the genus name in full the first time it appears in the title of a table, in the text of table, and in the caption of a figure or photograph.

Referring to unnamed or multiple species in a genus 

Use ‘sp.’ when referring to a single species from a genus when the species name is unknown, uncertain or unnamed:

A new species (Grevillea sp.) was discovered in the national park.

Use ‘spp.’ when referring to multiple species in a genus:

Many tree species (Eucalyptus spp. and Acacia spp.) regenerated after the fires.

Note that ‘sp.’ and ‘spp.’ are not set in italics.

When referring to the genus as a whole, use the genus name alone:

Culicoides biting midges are known to be vectors of various diseases   not   Culicoides spp. biting midges …

A genus name does not have a plural form (but see Common names derived from family and genus names for plurals of genus names used as common names):

Grevillea spp.   not   Grevilleas

Describing actions involving specific plants and animals

Latin binomial species names are abstract concepts and therefore cannot be used as the subject of a direct action. In this case, use the common name of the plant or animal concerned:

Tobacco plants (Nicotiana tabacum) have been inoculated ...   not   Nicotiana tabacum has been inoculated ... [ie the plant is inoculated, not the taxon]

Mice (Mus musculus) were fed a diet containing …   not   Mus musculus were fed … 

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