How animals are given scientific names

Codes of nomenclature

There are three main Codes of Nomenclature: the International Code of Zoological Nomenclature, covering animals; the International Code of Botanical Nomenclature, covering plants (including fungi); and the International Code of Nomenclature of Bacteria. Although there are quite a few similarities between the codes, there are also considerable differences and it is beyond the scope of this handout to compare the Zoological Code with the other two in any detail.

The history of Zoological nomenclature

1758  Linnaeus published the 10th edition of the Systema Naturae and in it consistently used his system of binomial nomenclature. This system was adopted by other naturalists but with no rules governing it so that by the middle of the 19th century there was confusion. The confusion was increased by the proliferation of new species resulting from the growth of Science and the voyages of exploration.

Hugh Strickland presented a Code of nomenclature to the British Association for the Advancement of Science (Charles Darwin was on its committee). It was translated and circulated widely round the world. It was revised in succeeding years.


Douvillé Code, based on the Stricklandian Code, adopted internationally by geologists and the American Ornithologists Union.


The First International Congress of Zoology in Paris adopted, in part, rules drawn up by Professor Raphael Blanchard.


Blanchard’s Code discussed at the Second International Congress of Zoology in Moscow.


International Commission of five zoologists appointed at the 3rd Congress in Leyden. Further members added later.


 A report by the Commission was adopted by the 5th Congress in Berlin.


The report was published as a Code in French, German and English. It was entitled Règles internationales de la Nomenclature zoologique. It contained no directives concerning types.


Amendments to Code at Boston Congress including provisions for generic types.


Amendments to Code at Monaco Congress including recommendations regarding types of species.


 Amendments to Code at Budapest Congress.


Amendments to Code at Padua Congress.


Formal rules and recommendations regarding type specimens adopted at the Paris Congress.


Publication of 1st edition of the

International Code of Zoological Nomenclature resulting from Congresses following the 2nd World War.


2nd edition of the International Code of Zoological Nomenclature.


At the 17th Congress of Zoology in Monaco, responsibility for future Codes was transferred from the International Zoological Congresses to the International Union of Biological Sciences.

1985 Publication of 3rd edition of the

International Code of Zoological Nomenclature.

1999  Publication of 4th edition of the

International Code of Zoological Nomenclature

The hierarchy of ranks

Organisms are placed in hierarchies so that one divide up the species into manageable chunks and so that one can see the relationship of species and groups to one another. The full hierarchy of ranks for animals is as follows (using a species of beetle as an example).

  • Kingdom: Animalia

  • Phylum: Arthropoda

  • Subphylum: Uniramia

  • Class: Hexapoda

  • Subclass: Insecta

  • Order: Coleoptera

  • Suborder: Polyphaga

  • [Supercohort]

  • [Cohort]

  • [Subcohort]

    • [FAM] Superfamily: CucujOIDEA

    • [FAM] Family: TenebrionIDAE

    • [FAM] Subfamily: TenebrionINAE

    • [FAM] Tribe: PlatynotINI

    • [FAM] Subtribe: Anomalipina

      • [GEN] Genus: Anomalipus

      • [GEN] Subgenus: Anomalipus

        • [SP] Species: Anomalipus (Anomalipus) plebejus Peringuey, 1896

        • [SP] Subspecies: A. (A.) plebejus plebejulus Endrödy Younga, 1988

          • [Variety] (not recognised by the Code)

The Zoological Code recognises three main types of names: family group names (FAM); genus group names (GEN); and species group names (SP). The other ranks are not controlled by the code so at these ranks you can choose the names you like (zoologists, with a few exceptions, try to coordinate as much as possible so that there is a minimum of chaos).

Superfamily names have the suffix -oidea; family names -idae; subfamily names -inae, and tribal names -ini. The genus name is always included with the species name to form the binomial. The subgenus to which it belongs (if there is one) can be included in brackets after the genus name and before the species name but inclusion of this name is not essential. Notice that the author of the name can be included at the end of the name. If the genus name is not the same as the one originally used by the author, then the author’s name is enclosed in brackets. For instance, Camponotus fulvopilosus (De Geer) was originally described by De Geer as Formica fulvopilosa.

When an author introduces a new name at a particular rank within the family group, that name can be used at other ranks within the family group as well. This is the Principle of Coordination (see later). For instance, within the ants there are the names Formicoidea, Formicidae, Formicinae and Formicini. All four of these names have the same author, date and type genus; they only differ in the suffix used for each rank. In practice, a name is rarely used at so many ranks. For instance, within the subfamily Formicinae is the tribe Camponotini; this name is not use at the subfamily rank because it was established later than the name Formicinae. This same Principle of Coordination applies to genus-group names (e.g. a subgenus name could later be used as a genus name) and species group names (e.g. a species name might later be used as a subspecies name).


Each family group name has a type genus, each genus group name has a type species, and each species group name has a type specimen or type series. Types are important because they are the reference points for each taxon. By comparing the types you can make a decision about whether two taxa are the same or not. In the late 19th century specimens were often labelled as types merely because they were ‘typical’ of the species. However, in its modern meaning a type is not necessary typical of the taxon it represents. A taxonomist might describe a new species from a single specimen which s/he designates as a holotype. At a later date more specimens of the species might be discovered and it might be found that the type is in fact at the extreme of variation for that species and therefore not typical. However, that specimen still remains the ultimate point of reference for that name.

In family group and genus group names, there are a number of different ways in which a type might be designated and the differences between them are best illustrated by examples (of ant genera). When Ettershank described the genus Nothidris he did designate a type species so this is a type by original designation. When Emery described the genus Chelaner he did not designate a type at the time but did so at a later date. This is a type by subsequent designation. When Santschi described the ant genus Oxyepoecus he did not designate a type species. However, he only listed one species under the genus so this species is regarded as the type species by monotypy.

The specimen or specimens used by the author for the description accompanying a species group name is/are regarded as the type specimen(s). The author usually labels the specimen as a type but this is not always the case and one has to compare the label of the specimen with the collection information accompanying the description to assess whether a specimen is a type or not. There are a number of different terms used for type specimens and some of these are listed below.

  • Holotype. A single specimen used by the author for describing the species or subspecies.

  • Paratype. Each specimen of a type series other than the holotype. What typically happens these days is that an author will describe a new species from a single specimen, the holotype, and then discuss variability in the species by referring to other specimens that s/he has designated as paratypes. The holotype and paratype(s) have usually been collected from the same locality but this does not have to be so. Authors often deposit paratypes in different museums in case the holotype and its associated types are destroyed. A paratype has a junior status to the holotype so if at a later date they are found to be different species (which sometimes happens), the paratype is discarded as a type of the taxon and the holotype retained.

  • Syntypes. If an author describes a species or subspecies from a number of specimens, these are referred to as syntypes and they all have equal status as types.

  • Lectotype. A person revising a particular group might take a syntype series and designate one particular specimen as the name-bearing type so that the species or subspecies is more closely circumscribed. This specimen is then called the lectotype if this change in type definition is published. Lectotypes are usually only designated when there is confusion in the syntype series.

  • Paralectotype. The remaining specimens of a syntype series after a lectotype has been designated.

  • Neotype. If the types for a particular species or subspecies name are thought to have been destroyed, one can designate a new type which is called a neotype. A neotype can only be designated in a revisionary work where there has been a critical study of the taxon in question and where the designation is necessary for resolving a taxonomic problem. One cannot designate a neotype as an end in itself. If the original type is later re-discovered, the neotype will fall away and be replaced by the original type.

  • Allotype. A paratype of opposite sex to the holotype. If the opposite sex is described at a later date to the original naming of the taxon, one cannot at this stage validly designate an allotype.

  • Cotype. A term is no longer used indicating a syntype or a paratype.

If the existing type of a species is useless for distinguishing the species (making the name a nomen dubium), an author can ask the Commission to allow him/her to designate a neotype instead.

The different sorts of names for animals

Vernacular names. General purpose names that are not proposed for zoological nomenclature. An organism can have any number of vernacular names in any number of languages. However, scientists of different nationalities need to be able to refer to the same taxon using a single name so as to avoid ambiguity. This is one of the main reasons why we have scientific names, governed by a code of rules.

Scientific names. Latin or latinized names for organisms. They can be derived from any language but must be converted to a latin form using latin letters (but including the letters "j", "k", "w" and "y"). A species scientific name consists of two components (ie a binomen), the genus name and the species name. A subspecies scientific name consists of three components (ie a trinomen), the genus name, the species name and the subspecies name. All other names above the species level (eg Families) consist of one name.

Available names (= validly published names in Bot. code). When a name is proposed and it meets the criteria of availability, it is added to the pool of names that are available for use. The main criteria for availability are as follows.

  1. The name must have been validly published (see below) after 1757.

  2. It must be spelled in latin letters.

  3. The Principle of binomial nomenclature must have been used consistently in the publication.

  4. It must be accompanied by a description of the taxon or by a reference to a description of the taxon. Names published before 1930 are more lenient on this point - one of the following ‘indications’ is enough to replace the description: in family group names, the genus name from which the family name is formed (e.g. Formica for Formicidae) indicates what the family looks like; in genus group names, referring to a species within the genus is sufficient. Even an illustration or a reference to an illustration is regarded as an adequate indication to what the taxon looks like. After 1930 the Code does not allow these indications and in addition it demands that a type species (see later) be proposed for each new genus name.

Available names are either valid or invalid.

  • Valid names (= ‘correct’ names in Bot. Code). These are correct scientific names for taxa. They are not synonyms or homonyms. A valid name is not necessarily inviolate - a taxonomist might revise the group and synonymise the name making it invalid. A later taxonomist might unsynonymise the name hence making it valid again

  • Invalid names. These are incorrect scientific names for taxa. They can be subdivided as follows.

    • Subjectively invalid names. Names that have been made invalid as a result of a judgement that is a matter of opinion.

      • Junior subjective synonyms (taxonomic synonyms in Bot. code). Subjective synonyms have different types thought to belong to the same taxon. Of a pair of subjective synonyms, a junior subjective synonym is the one that was described at the later date. For instance, a taxonomist might compare the types for two different names. They look slightly different from one another but s/he decides that they are actually the same species. S/he therefore makes the more recent name a junior subjective synonym or the older name. This is a subjective decision because another taxonomist might have a different opinion and decide that the types are of different species and hence both names are valid.

      • Junior secondary homonyms. Apply to species group names only. For instance, Santschi in 1909 described the ant species Tetramorium silvestrii. In 1915 Emery described the ant species Triglyphothrix silvestrii. So far everything is fine and they are both valid species. However, in 1985 Bolton published a paper in which he (subjectively) synonymised Triglyphothrix with Tetramorium because there were no consistent characters separating them. In doing so he caused a number of secondary homonyms to appear including Tetramorium silvestrii and Triglyphothrix silvestrii which are different species with different types but which now had the same name. Bolton therefore replaced the junior secondary homonym Triglyphothrix silvestrii by the new name Tetramorium surrogatum.

      • Conditionally suppressed names. A taxonomist can apply to The International Commission on Zoological Nomenclature to have a senior subjective synonym supressed, thus reversing the order of priority. This usually occurs when the junior synonym has been in common usage whereas the senior synonym has been ignored and forgotten for a long time. If the synonym is conditionally supressed it means that if the two names are later unsynonymised, the supressed name can be used as a valid name again.

    • Objectively invalid names. Names that have been made invalid for factual reasons.

      • Junior objective synonyms (nomenclatural synonyms in Bot. code). The later established of two names that have the same type.

      • Junior homonyms in the family group and genus group. Two names that have the same spelling but which refer to different taxa. For instance, there is a fish genus called Acantholepis and there was an ant genus Acantholepis. The ant genus is a junior homonym and has been replaced by the name Lepisiota.

      • Junior primary homonyms in the species group. Primary homonyms occur when two authors each describe a different taxon but use the same genus and species names. Primary homonyms are different from secondary homonyms in that they were originally homonyms, they did not become homonyms secondarily as a result of the synonymising of two genera. A junior primary homonym cannot become a valid name by being transferred to another genus. For instance, Latrielle in 1802 described an ant species, now in the genus Pheidole, as Formica longipes, Jerdon in 1851 used the same name for a species now recognised as belonging to the genus Anoplolepis, and Gerstäcker in 1859 used the same name for a species of ant now belonging to the genus Camponotus. Only Latrielle’s name stands as it was the earliest published. The name Anoplolepis longipes has now been replaced by the oldest available junior synonym which is Formica gracilipes Smith, F. 1857, so the species is now known as Anoplolepis gracilipes. As Camponotus longipes had no junior synonyms, B. Bolton in his catalogue of ants created a new name Camponotus etiolipes to replace this junior primary homonym and he takes the authorship of this new name.

      • Totally suppressed names. The Commission of Zoological Nomenclature decide that an available name is never to be used as a valid name despite the fact that it might be a senior synonym or homonym.

      • Partially suppressed names. Confusingly similar term to totally suppressed names.

Unavailable names. Scientific names that do not fit the criteria of availability (see above). An unavailable name is known as a Nomen nudum.

According to the latest (4th edition) of the Code, an author should not displace a name that has been regularly used as valid (by at least 10 authors in 25 publications during the past 50 years covering at least 10 years) by an earlier synonym or homonym which has not been used as valid since 1899.

The Principles of zoological nomenclature

There are six principles stated in the Code of Zoological Nomenclature. Most of these have already been implied earlier in this handout but they are all included here for completeness.

Principle of binomial nomenclature. "The scientific name of a species, and not of a taxon of any other rank, is a combination of two names (a binomen), the first being the generic name and the second the specific name. The principle applies to the names of species, and the fact that family-group and genus-group names are uninomial and subspecies names trinomial is not inconsistent with the principle."

Principle of name-bearing types. "The principle that each nominal taxon has, actually or potentially, its name-bearing type that provides the objective standard of reference by which the application of the name is determined."

Principle of priority. "The principle that the valid name of a taxon is the oldest name applied to it, provided that the name is not invalidated by any provision of the Code or by any ruling by the Commission."

Principle of coordination. "The principle that within the family group, or the genus group, or the species group, a name established for a taxon at any rank in the group is deemed to be simultaneously established with the same author and date for taxa based on the same name-bearing type at other ranks in the group."

Principle of homonymy. "The principle that an available name that is a junior homonym of another available name must not be used as a valid name."

Principle of the first reviser. "The principle that the relative precedence of two or more names or nomenclatural acts published on the same date, or of different original spellings of the same name, is determined by the first reviser."

The process of naming a new species

  1. Allocate the species to a particular genus eg. Carebara.
  2. Give it a latinized species name eg capensis that is not a homonym of some previous name.
  3. Describe the species from the type(s). After 1999, this species account must include information on the collection where the type is or will be deposited.
  4. Publish these details. By printing multiple identical copies of your paper and making them obtainable to those who are interested, you are producing a valid publication. However, it is strongly recommended in the Code that the work is published by conventional means and that you do not publish by photocopying, microfiche or some other ill-defined process. In other words it is best to publish new scientific names or nomenclatural acts in books or scientific journals. Read-only cd's are now (after 1999) also acceptable provided they are distributed widely and deposited in at least 5 major publicly accessible libraries. The date of publication, very important because of the Principle of Priority, is the date on which the work is first distributed to the public, which does not always correlate with the date given in the publication.
  5. After 1999, the new name in the publication must have some wording after it to explicitly indicate that it is new e.g. "sp. nov.".



Text by Hamish Robertson


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