Nomenclature codes or codes of nomenclature are the various rulebooks that govern the naming of living organisms. Standardizing the scientific names of biological organisms allows researchers to discuss findings (including the discovery of new species).
As the study of biology became increasingly specialized, specific codes were adopted for different types of organism.
To an end-user who only deals with names of species, with some awareness that species are assignable to genera, families, and other taxa of higher ranks, it may not be noticeable that there is more than one code, but beyond this basic level these are rather different in the way they work.
In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomial name (which may be shortened to just "binomial"), a binomen, binominal name, or a scientific name; more informally it is also historically called a Latin name. In the ICZN, the system is also called binominal nomenclature, [1] "binomi'N'al" with an "N" before the "al", which is not a typographic error, meaning "two-name naming system". [2]
The first part of the name – the generic name – identifies the genus to which the species belongs, whereas the second part – the specific name or specific epithet – distinguishes the species within the genus. For example, modern humans belong to the genus Homo and within this genus to the species Homo sapiens . Tyrannosaurus rex is likely the most widely known non-human binomial. [3]
The formal introduction of this system of naming species is credited to Carl Linnaeus, effectively beginning with his work Species Plantarum in 1753. [4] But as early as 1622, Gaspard Bauhin introduced in his book Pinax theatri botanici (English, Illustrated exposition of plants) containing many names of genera that were later adopted by Linnaeus. [5] The introduction of two-part names (binominal nomenclature) for species by Linnaeus was a welcome simplification because as our knowledge of biodiversity expanded, so did the length of the names, many of which had become unwieldy. [6]
With all naturalists worldwide adopting binominal nomenclature, there arose several schools of thought about the details. It became ever more apparent that a detailed body of rules was necessary to govern scientific names. From the mid-19th century onwards, there were several initiatives to arrive at worldwide-accepted sets of rules. Presently nomenclature codes govern the naming of:
The starting point, that is the time from which these codes are in effect (usually retroactively), varies from group to group, and sometimes from rank to rank. [7] In botany and mycology, the starting point is often 1 May 1753 (Linnaeus, Species plantarum ). In zoology, it is 1 January 1758 (Linnaeus, Systema Naturae, 10th Edition). On the other hand, bacteriology started anew, making a clean sweep in 1980 (Skerman et al., "Approved Lists of Bacterial Names"), although maintaining the original authors and dates of publication. [8]
Exceptions in botany: [9] [10] [11]
Exceptions in zoology: [13]
There are also differences in the way codes work. For example, the ICN (the code for algae, fungi and plants) forbids tautonyms, while the ICZN, (the animal code) allows them.
These codes differ in terminology, and there is a long-term project to "harmonize" this. For instance, the ICN uses "valid" in "valid publication of a name" (=the act of publishing a formal name), with "establishing a name" as the ICZN equivalent. The ICZN uses "valid" in "valid name" (="correct name"), with "correct name" as the ICN equivalent. Harmonization is making very limited progress.
There are differences in respect of what kinds of types are used. The bacteriological code prefers living type cultures, but allows other kinds. There has been ongoing debate regarding which kind of type is more useful in a case like cyanobacteria. [14]
A more radical approach was made in 1997 when the IUBS/IUMS International Committee on Bionomenclature (ICB) presented the long debated Draft BioCode, proposed to replace all existing Codes with a harmonization of them. [15] [16] The originally planned implementation date for the BioCode draft was January 1, 2000, but agreement to replace the existing Codes was not reached.
In 2011, a revised BioCode was proposed that, instead of replacing the existing Codes, would provide a unified context for them, referring to them when necessary. [17] [18] [19] Changes in the existing codes are slowly being made in the proposed directions. [20] [21] However, participants of the last serious discussion of the draft BioCode concluded that it would probably not be implemented in their lifetimes. [22]
Many authors encountered problems in using the Linnean system in phylogenetic classification. [23] In fact, early proponents of rank-based nomenclature, such as Alphonse de Candolle and the authors of the 1886 version of the American Ornithologists' Union code of nomenclature already envisioned that in the future, rank-based nomenclature would have to be abandoned. [24] [6] Another Code that was developed since 1998 is the PhyloCode , which now regulates names defined under phylogenetic nomenclature instead of the traditional Linnaean nomenclature. This new approach requires using phylogenetic definitions that refer to "specifiers", analogous to "type" under rank-based nomenclature. Such definitions delimit taxa under a given phylogeny, and this kind of nomenclature does not require use of absolute ranks. The Code took effect in 2020, with the publication of Phylonyms, a monograph that includes a list of the first names established under that code.
Some protists, sometimes called ambiregnal protists, have been considered to be both protozoa and algae, or protozoa and fungi, and names for these have been published under either or both of the ICZN and the ICN. [25] [26] The resulting double language throughout protist classification schemes resulted in confusion. [27] [28] [29]
Groups claimed by both protozoologists and phycologists include euglenids, dinoflagellates, cryptomonads, haptophytes, glaucophytes, many heterokonts (e.g., chrysophytes, raphidophytes, silicoflagellates, some xanthophytes, proteromonads), some monadoid green algae (volvocaleans and prasinophytes), choanoflagellates, bicosoecids, ebriids and chlorarachniophytes.
Slime molds, plasmodial forms and other "fungus-like" organisms claimed by both protozoologists and mycologists include mycetozoans, plasmodiophorids, acrasids, and labyrinthulomycetess. Fungi claimed by both protozoologists and mycologists include chytrids, blastoclads, and the gut fungi.
Other problematic groups are the Cyanobacteria (ICNP/ICN) and Microsporidia (ICZN/ICN).
The zoological code does not regulate names of taxa lower than subspecies or higher than superfamily. There are many attempts to introduce some order on the nomenclature of these taxa, [30] [31] including the PhyloCode, the Duplostensional Nomenclatural System, [32] [33] and circumscriptional nomenclature. [34] [35]
The botanical code is applied primarily to the ranks of superfamily and below. There are some rules for names above the rank of superfamily, but the principle of priority does not apply to them, and the principle of typification is optional. These names may be either automatically typified names or be descriptive names. [36] [37] In some circumstances, a taxon has two possible names (e.g., Chrysophyceae Pascher, 1914, nom. descrip.; Hibberd, 1976, nom. typificatum). Descriptive names are problematic, once that, if a taxon is split, it is not obvious which new group takes the existing name. Meanwhile, with typified names, the existing name is taken by the new group that still bears the type of this name. However, typified names present special problems for microorganisms. [29]
Genus is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.
In taxonomy, binomial nomenclature, also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomial name, a binomen, binominal name, or a scientific name; more informally it is also historically called a Latin name. In the International Code of Zoological Nomenclature (ICZN), the system is also called binominal nomenclature, with an "n" before the "al" in "binominal", which is not a typographic error, meaning "two-name naming system".
In biology, a subgenus is a taxonomic rank directly below genus.
In biology, a tribe is a taxonomic rank above genus, but below family and subfamily. It is sometimes subdivided into subtribes. By convention, all taxa ranked above species are capitalized, including both tribe and subtribe.
In biology, trinomial nomenclature is the system of names for taxa below the rank of species. These names have three parts. The usage is different in zoology and botany.
The International Code of Nomenclature for algae, fungi, and plants is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all those "traditionally treated as algae, fungi, or plants". It was formerly called the International Code of Botanical Nomenclature (ICBN); the name was changed at the International Botanical Congress in Melbourne in July 2011 as part of the Melbourne Code which replaced the Vienna Code of 2005.
The International Code of Phylogenetic Nomenclature, known as the PhyloCode for short, is a formal set of rules governing phylogenetic nomenclature. Its current version is specifically designed to regulate the naming of clades, leaving the governance of species names up to the rank-based nomenclature codes.
In biology, a type is a particular specimen of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes the defining features of that particular taxon. In older usage, a type was a taxon rather than a specimen.
In the scientific name of organisms, basionym or basyonym means the original name on which a new name is based; the author citation of the new name should include the authors of the basionym in parentheses. The term "basionym" is used in both botany and zoology. In zoology, alternate terms such as original combination or protonym are sometimes used instead. Bacteriology uses a similar term, basonym, spelled without an i.
In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name.
In biological nomenclature, a syntype is any one of two or more biological types that is listed in a description of a taxon where no holotype was designated. Precise definitions of this and related terms for types have been established as part of the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants.
Botanical nomenclature is the formal, scientific naming of plants. It is related to, but distinct from taxonomy. Plant taxonomy is concerned with grouping and classifying plants; botanical nomenclature then provides names for the results of this process. The starting point for modern botanical nomenclature is Linnaeus' Species Plantarum of 1753. Botanical nomenclature is governed by the International Code of Nomenclature for algae, fungi, and plants (ICN), which replaces the International Code of Botanical Nomenclature (ICBN). Fossil plants are also covered by the code of nomenclature.
In botany, the correct name according to the International Code of Nomenclature for algae, fungi, and plants (ICN) is the one and only botanical name that is to be used for a particular taxon, when that taxon has a particular circumscription, position and rank. Determining whether a name is correct is a complex procedure. The name must be validly published, a process which is defined in no less than 16 Articles of the ICN. It must also be "legitimate", which imposes some further requirements. If there are two or more legitimate names for the same taxon, then the correct name is the one which has priority, i.e. it was published earliest, although names may be conserved if they have been very widely used. Validly published names other than the correct name are called synonyms. Since taxonomists may disagree as to the circumscription, position or rank of a taxon, there can be more than one correct name for a particular plant. These may also be called synonyms.
In botanical nomenclature, author citation is the way of citing the person or group of people who validly published a botanical name, i.e. who first published the name while fulfilling the formal requirements as specified by the International Code of Nomenclature for algae, fungi, and plants (ICN). In cases where a species is no longer in its original generic placement, both the authority for the original genus placement and that for the new combination are given.
In zoological nomenclature, the valid name of a taxon is the correct scientific name for that taxon. The valid name must be used for that taxon, regardless of any other name that may currently be used for that taxon, or may previously have been used. A name can only be valid when it is an available name under the International Code of Zoological Nomenclature (ICZN); if a name is unavailable, then it cannot be considered either valid or invalid.
A conserved name or nomen conservandum is a scientific name that has specific nomenclatural protection. That is, the name is retained, even though it violates one or more rules which would otherwise prevent it from being legitimate. Nomen conservandum is a Latin term, meaning "a name to be conserved". The terms are often used interchangeably, such as by the International Code of Nomenclature for Algae, Fungi, and Plants (ICN), while the International Code of Zoological Nomenclature favours the term "conserved name".
The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently.
Priority is a principle in biological taxonomy by which a valid scientific name is established based on the oldest available name. It is a decisive rule in botanical and zoological nomenclature to recognise the first binomial name given to an organism as the correct and acceptable name. The purpose is to select one scientific name as a stable one out of two or more alternate names that often exist for a single species.
In zoological nomenclature, an available name is a scientific name for a taxon of animals that has been published after 1757 and conforming to all the mandatory provisions of the International Code of Zoological Nomenclature for the establishment of a zoological name. In contrast, an unavailable name is a name that does not conform to the rules of that code and that therefore is not available for use as a valid name for a taxon. Such a name does not fulfil the requirements in Articles 10 through 20 of the Code, or is excluded under Article 1.3.
In mycology, a sanctioned name is a name that was adopted in certain works of Christiaan Hendrik Persoon or Elias Magnus Fries, which are considered major points in fungal taxonomy.