The INTERNATIONAL CODE OF ZOOLOGICAL NOMENCLATURE (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals . It is also informally known as the ICZN CODE, for its publisher, the International Commission on Zoological Nomenclature (which shares the acronym "ICZN"). The rules principally regulate:
* How names are correctly established in the frame of binominal nomenclature * Which name must be used in case of name conflicts * How scientific literature must cite names
Zoological nomenclature is independent of other systems of nomenclature, for example botanical nomenclature . This implies that animals can have the same generic names as plants.
The rules and recommendations have one fundamental aim: to provide the maximum universality and continuity in the naming of all animals, except where taxonomic judgment dictates otherwise. The Code is meant to guide only the nomenclature of animals, while leaving zoologists freedom in classifying new taxa .
In other words, whether a species itself is or is not a recognized
entity is a subjective decision, but what name should be applied to it
is not. The Code applies only to the latter, not to the former. A new
animal name published without adherence to the Code may be deemed
simply "unavailable" if it fails to meet certain criteria, or fall
entirely out of the province of science (e.g., the "scientific name"
Loch Ness Monster
The rules in the Code determine what names are valid for any taxon in the family group, genus group, and species group. It has additional (but more limited) provisions on names in higher ranks . The Code recognizes no case law . Any dispute is decided first by applying the Code directly, and not by reference to precedent.
The Code is also retroactive or retrospective , which means that previous editions of the Code, or previous other rules and conventions have no force any more today, and the nomenclatural acts published 'back in the old times' must be evaluated only under the present edition of the Code. In cases of disputes concerning the interpretation, the usual procedure is to consult the French Code, lastly a case can be brought to the Commission who has the right to publish a final decision.
* 1 Principles
* 1.1 Principle of binominal nomenclature
Principle of Priority
* 2 Structure
* 2.1 Gender agreement
* 3 History * 4 Commission * 5 Local usage and name changes * 6 Citation * 7 Versions * 8 See also * 9 References * 10 External links
In regulating the names of animals it holds by six central principles, which were first set out (as Principles) in the third edition of the Code (1985):
PRINCIPLE OF BINOMINAL NOMENCLATURE
This is the principle that the scientific name of a species, and not of a taxon at any other rank, is a combination of two names; the use of a trinomen for the name of a subspecies and of uninominal names for taxa above the species group is in accord with this principle.
This means that in the system of nomenclature for animals, the name
of a species is composed of a combination of a generic name and a
specific name ; together they make a "binomen ". No other rank can
have a name composed of two names. Examples:
* Taxa at a rank above species have a name composed of one name, a "uninominal name".
In botanical nomenclature, the equivalent for "binominal nomenclature" is "binary nomenclature" (or sometimes "binomial nomenclature ").
PRINCIPLE OF PRIORITY
Principle of Priority
This is the principle that the correct formal scientific name for an
animal taxon , the valid name , correct to use, is the oldest
available name that applies to it. It is the most important
principle—the fundamental guiding precept that preserves zoological
nomenclature stability. It was first formulated in 1842 by a committee
appointed by the
Example: Nunneley 1837 established
Limax maculatus (Gastropoda),
Wiktor 2001 classified it as a junior synonym of
There are approximately 2-3 million cases of this kind for which this Principle is applied in zoology.
PRINCIPLE OF COORDINATION
The principle of coordination is that within the family group, genus group and species group, a name established for a taxon at any rank in the group is simultaneously established with the same author and date for taxa based on the same name-bearing type at other ranks in the corresponding group. In other words, publishing a new zoological name automatically and simultaneously establishes all corresponding names in the relevant other ranks with the same type.
In the species-group, publishing a species name (the binomen )
In the genus-group, similarly, publishing the name of a genus also establishes the corresponding name of a subgenus (or vice versa): genus Giraffa Linnaeus, 1758 and subgenus Giraffa (Giraffa) Linnaeus, 1758.
In the family-group, publication of the name of a family, subfamily, superfamily (or any other such rank) also establishes the names in all the other ranks in the family group (family Giraffidae, superfamily Giraffoidea, subfamily Giraffinae).
Author citations for such names (for example a subgenus) are the same as for the name actually published (for example a genus). It is immaterial if there is an actual taxon to which the automatically established name applies; if ever such a taxon is recognised, there is a name available for it.
PRINCIPLE OF THE FIRST REVISER
This is the principle that in cases of conflicts between simultaneously published divergent acts, the first subsequent author can decide which has precedence. It supplements the principle of priority , which states that the first published name takes precedence. The Principle of the First Reviser deals with situations that cannot be resolved by priority. These items may be two or more different names for the same taxon , two or more names with the same spelling used for different taxa, two or more different spellings of a particular name, etc. In such cases, the first subsequent author who deals with the matter and chooses and publishes the decision in the required manner is the First Reviser, and is to be followed.
Linnæus 1758 established Strix scandiaca and Strix noctua (Aves), for which he gave different descriptions and referred to different types, but both taxa later turned out to refer to the same species, the snowy owl . The two names are subjective synonyms. Lönnberg 1931 acted as First Reviser, cited both names and selected Strix scandiaca to have precedence.
A problem is that sometimes the First Reviser is unknown. For the sperm whale Linnæus 1758 established three subjective synonyms, Physeter macrocephalus, Physeter catodon, and Physeter microps. The First Reviser remains unknown; both Ph. macrocephalus and Ph. catodon are used.
PRINCIPLE OF HOMONYMY
This is the principle that the name of each taxon must be unique. Consequently, a name that is a junior homonym of another name must not be used as a valid name.
It means that any one animal name, in one particular spelling, may be used only once (within its group). This is usually the first-published name; any later name with the same spelling (a homonym ) is barred from being used. The Principles of Priority and the First Reviser apply here. For family-group names the termination (which is rank-bound) is not taken into account.
Genera are homonyms only if exactly the same — a one-letter difference is enough to distinguish them.
Examples: Argus Bohadsch, 1761 (Gastropoda) (was made available for
homonymy by ICZN in Opinion 429, Bohadsch 1761 was non-binominal -
this had the effect that no other one of the various following names
Argus can be used for a taxon) Argus Scopoli, 1763 (Lepidoptera:
Lycaenidae: Polyommatinae) Argus Scopoli, 1777 (Lepidoptera:
Nymphalidae: Satyrinae) Argus Poli, 1791 (Bivalvia) Argus Temminck,
1807 (Aves) Argus Lamarck, 1817 (Lepidoptera: Hesperiidae) Argus
Walckenaer, 1836 (Araneae) Argus Gerhard, 1850 (Lepidoptera:
Lycaenidae: Theclinae) Homonyms of Argus are not:
Example: Nunneley (1837) established
Limax maculatus (Gastropoda),
Wiktor (2001) classified it as a junior synonym of
Art. 59.3 states that in exceptional cases, junior secondary homonyms replaced before 1961 by substitute names can become invalid, "...unless the substitute name is not in use," an exception of the exception. However, the ICZN Code does not give an example for such a case. It seems that this passage in the ICZN Code is widely ignored. It also does not define what the expression "is not in use" should mean.
Example: Glischrus caelata Studer, 1820 (Gastropoda) was once classified in the genus Helix , and became a junior secondary homonym of Helix caelata , 1801. Locard (1880) established a replacement name Helix glypta , which has very rarely been used. The species is now known as Trochulus caelatus (Studer, 1820), and Art. 59.3 is commonly ignored.
DOUBLE HOMONYMY (genus and species) is no homonymy: if the genera are homonyms and belong to different animal groups, the same specific names can be used in both groups.
Examples: The name Noctua Linnæus, 1758 was established for a lepidopteran subgenus. In 1764 he established a genus Noctua Linné ,1764 for birds, ignoring that he had already used this name a few years ago in Lepidoptera. Noctua Linné, 1764 (Aves) is a junior homonym of Noctua Linnæus, 1758 (Lepidoptera). Garsault (1764) used Noctua for a bird and established a name Noctua caprimulgus Garsault, 1764 (Aves). Fabricius (1775) established a name Noctua caprimulgus Fabricius, 1775 (Lepidoptera), thus creating a double homonym. Double homonymy is no homonymy, both names are available. The same happened with Noctua variegata Jung, 1792 (Lepidoptera) and Noctua variegata Quoy & Gaimard, 1830 (Aves).
For DISAMBIGUATING one genus-group name from its homonym, it is important to cite author and year. Citing the author alone is often not sufficient.
The name Ansa can only be used for a lepidopteran taxon. If that name cannot be used (for example because an older name established prior to 1858 takes precedence), this does not mean that the 1868 name can be used for a hemipteran genus. The only option to use the 1868 name for the hemipteran taxon is to get the 1858 name officially suppressed by the Commission .
In some cases, the same genus-group or species-group name was published in the same year by the same author. In these cases it would be useful to cite the page where the name was established. Amydona Walker, 1855 (Lepidoptera: Limacodidae) (p. 1110), not Amydona Walker, 1855 (Lepidoptera: Lasiocampidae) (p. 1413) Betousa Walker, 1865 (Lepidoptera: Thyridae) (p. 1111), not Betousa Walker, 1865 (Lepidoptera: Noctuidae) (p. 1208). Cicada variegata Fabricius, 1775 (p. 684), not Cicada variegata Fabricius, 1775 (p. 686) (both Auchenorrhyncha). Noctua marginata Fabricius, 1775 (p. 597), not Noctua marginata Fabricius, 1775 (p. 610) (both Lepidoptera: Noctuidae). Clausilia (Albinaria) oertzeni Boettger, 1889 (p. 42), not Clausilia (Albinaria) schuchi var. oertzeni Boettger, 1889 (p. 52) (both Gastropoda: Clausiliidae).
There are cases where two homonyms were established by the same author in the same year on the same page: Zonites verticillus var. graeca Kobelt, 1876 (Gastropoda) (p. 48), not Zonites albanicus var. graeca Kobelt, 1876 (p. 48).
Animal, plant, and fungi nomenclature are entirely independent from each other. The most evident shortcoming of this situation (for their use in biodiversity informatics ) is that the same generic name can be used simultaneously for animals and plants. For this kind of homonyms the expression "hemihomonyms" is sometimes used. Far more than 1000 such names are known.
Examples: The generic name Dryas L. (1753) represents a genus of magnoliophytan plants (family Rosaceae), and at the same time Dryas Hübner, 1807 is also a lepidopteran insect genus (family Nymphalidae). The genus Tandonia was established in animals (Gastropoda: Tandonia ), in plants (Euphorbiaceae) and in Fungi (Ascomycetes). Other examples for sometimes well known plant names with zoological equivalents are Aotus (Fabaceae and Mammalia), Arenaria (Caryophyllaeceae and Aves), Betula(Betulaceae and Hymenoptera), Chloris (Cactaceae and Aves), Dugesia (Asteraceae and Plathelminthes), Erica (Ericaceae and Araneae), Hystrix (Poaceae and Mammalia), Iris (Asparagales and Orthoptera), Liparis (Orchidaceae and Actinopterygii), Phalaenopsis (Asparagales and Aves), Pinus (Pinaceae and Mollusca), Prunella (Lamiaceae and Aves), Ricinus (Fabaceae and Acari), Taxus (Taxaceae and Mammalia), Typha (Typhaceae and Porifera), Ulva (Ulvophyceae and Lepidoptera), Viola (Violaceae and Lepidoptera).
For names above the family level, the Principle of Homonymy does not apply.
Examples: PULMONATA is usually used for a very prominent group in
Homonyms occur relatively rarely in families (only if generic names are identical or very similar and adding an ending "-idae" produces identical results). Discovering such a homonymy usually produces the same problems as if there were no rules: conflicts between entirely independent and unconnected groups of taxonomists working in different animal groups. Very often the Commission must be asked to take a decision.
Examples: Bulimina (Foraminifera) and
Buliminus (Gastropoda) give
both BULIMINIDAE, and both families were used since the 1880s. When
the homonymy was discovered 110 years later in the 1990s, the younger
(gastropod) taxon had to receive a new family name, and the Commission
needed was asked for a solution (Opinion 2018).
Claria (Rotifera) and
PRINCIPLE OF TYPIFICATION
This is the principle that each nominal taxon in the family group, genus group, or species group has—actually or potentially—a name-bearing type fixed that provides the objective standard of reference that determines what the name applies to.
This means that any named taxon has a name-bearing type , which allows the objective application of that name. Any family-group name must have a type genus, any genus-group name must have a type species, and any species-group name can (not must) have one or more type specimens (holotype, lectotype, neotype, syntypes, or others), usually deposited in a museum collection. The type genus for a FAMILY-GROUP NAME is simply the genus that provided the stem to which was added the ending "-idae" (for families). Example: The family name Spheniscidae has as its type genus the genus Spheniscus Brisson, 1760.
The type species for a GENUS-GROUP NAME is more complicated and
follows exactly defined provisions in Art. 67-69.
Example: The correctly cited type species of Locusta Linnæus, 1758 (Caelifera) is Gryllus migratorius Linnæus, 1758, not Locusta migratoria (Linnæus, 1758).
Designation and fixation have different meanings. A designation is the proposal of the type species. It is not necessary to have spelled the name of the genus or species correctly with correct authors (Art. 67.2.1, 67.6, 67.7), type species are always the correctly spelled name. If the designation is valid, the type species is fixed.
A designation can also be invalid and ineffective—for example—if the genus had already a previously fixed type species, or if a type species was proposed that was not originally included, or contradicted the description or figure for a genus for which no species had originally been included.
There are various possible modes of type species designation. This is their order of legal importance, with approximate proportions of occurrence and examples:
* Superior type fixation:
Designation by ICZN under the plenary powers (3 %) Example: Galba
Schrank, 1803 (Gastropoda) was established with one species included,
* Type fixation in the original work:
Original designation (31 %) Examples: Montfort 1810 established
Theodoxus (Gastropoda) and designated
Montfort 1810 as type species (now
Theodoxus fluviatilis ). Vest 1867
established the subgenus Clausilia (Isabellaria) (Gastropoda) and
designated Clausilia isabellina Pfeiffer, 1842 as type species (now
Isabellaria isabellina ). Riedel 1987 established the genus
Turcozonites (Gastropoda) and designated Zonites wandae Riedel, 1982
as type species (now Turcozonites wandae ). Monotypy (28 %)
The names in the family, genus, and species groups are fully regulated by the provisions in the Code. There is no limitation to the number of ranks allowed in the family group. The genus group has only two ranks: genus and subgenus . The species group has only two ranks: species and subspecies .
In the species group GENDER AGREEMENT applies. The name of a species,
in two parts, a binomen , say,
* For instance, the generic name Equus is masculine; in the name
Equus africanus the specific name africanus is an adjective, and its
ending follows the gender of the generic name.
Equus zebra the specific name zebra is a noun, it may not be
"corrected" to "Equus zebrus".
Equus quagga burchellii
If a species is moved, therefore, the spelling of an ending may need to change. If Gryllus migratorius is moved to the genus Locusta , it becomes Locusta migratoria . Confusion over Latin grammar has led to many incorrectly formed names appearing in print. An automated search may fail to find all the variant spellings of a given name (e.g., the spellings atra and ater may refer to the same species).
Many laymen, and some scientists, object to continued adherence to
this rule, especially those who work with butterflies and moths . This
is for historical reasons. In 1758 , Linnæus placed all butterflies
in the genus
The 1905 Rules became increasingly outdated. They soon sold out, and it became increasingly difficult to obtain to a complete set of the Rules with all amendments. In Copenhagen 1953 the French and English texts of the Rules were declared of equivalent official force, and a declaration was approved to prepare a new compilation of the rules. In 1958, an Editorial Committee in London elaborated a completely new version of the nomenclatural rules, which were finally published as the first edition of the ICZN Code on 9 November 1961.
The 2nd edition of the Code (only weakly modified) came in 1963. The last zoological congress to deal with nomenclatural problems took place in Monte Carlo 1972, since by then the official zoological organs no longer derived power from zoological congresses. The 3rd edition of the Code came out in 1985. The present edition is the 4th edition, effective since 2000. These Code editions were elaborated by editorial committees appointed by the International Commission on Zoological Nomenclature . The ICZN Commission takes its power from a general biological congress (IUBS, International Union of Biological Sciences ). The Editorial Committee for the 4th edition was composed of seven persons. Such new editions of the ICZN Code are not democratically approved by those taxonomists who are forced to follow the Code's provisions, neither do taxonomists have the right to vote for the members of the Commission or the Editorial Committee.
As the Commission may alter the Code (by declarations and amendments) without issuing a new edition of the book, the current edition does not necessarily contain the actual provision that applies in a particular case. The Code consists of the original text of the 4th edition and Declaration 44. The Code is published in an English and a French version; both versions are official and equivalent in force, meaning, and authority. This means that if something in the English Code is unclear or its interpretation ambiguous, the French version is decisive, and if there is something unclear in the French Code, the English version is decisive.
The rules in the Code apply to all users of zoological names. However, its provisions can be interpreted, waived, or modified in their application to a particular case when strict adherence would cause confusion. Such exceptions are not made by an individual scientist, no matter how well-respected within the field, but only by the International Commission on Zoological Nomenclature , acting on behalf of all zoologists. The Commission takes such action in response to proposals submitted to it.
The latest amendments enacted by the Commission concern electronic
publishing, which is now permitted for works published under an ISBN
LOCAL USAGE AND NAME CHANGES
The ICZN is used by the scientific community worldwide. Changes are governed by guidelines in the code. Local changes, such as the changes proposed by the Turkish government , are not recognised by ICZN.
The current (4th Edition) Code should be cited in scientific papers as ICZN (1999) and in reference lists as:-
ICZN 1999. International Code of Zoological Nomenclature. Fourth Edition. The International Trust for Zoological Nomenclature, London, UK. 306 pp.
* Strickland, H.E. 1843. Report of a Committee appointed "to
consider of the rules by which the Nomenclature of
* ^ ICZN Code Art. 5 * ^ ICZN Code Art. 86.3 * ^ ICZN Code Art. 89 * ^ A B C D ICZN Code Glossary * ^ ICZN Code Glossary, "binomen" * ^ ICZN Code Art. 24.2. * ^ The publication by (1801) has not been unambiguously recognized as published work in the sense of the Code Art. 8, which might be another reason to ignore Art. 59.3 in this case. * ^ Moscow State University hemihomonyms database * ^ These proportions apply to 366 verified European non-marine mollusc genera (), presumed to represent a more-or-less representative animal group. * ^ "Subsequent absolute tautonymy" is not used as a term in the Code's 4th edition, but it is a logical consequence of the usage of the term "subsequent monotypy". * ^ AnimalBase: List of all taxa, sorted by genus names, Papilio * ^ Allen, JA (1897). "The Merton Rules". Science. 6 (131): 9–19. PMID 17819182 . doi :10.1126/science.6.131.9 . * ^ Strickland, HE (1878). Rules for Zoological Nomenclature. John Murray, London. * ^ Dayrat, B (2010). "Celebrating 250 Dynamic Years of Nomenclatural Debates". In Polaszek, A. Systema Naturae 250 - The Linnaean Ark (PDF). Taylor and Francis. * ^ Blanchard, R., Maehrenthal, F. von & Stiles, C. W. 1905. Règles internationales de la nomenclature zoologique adoptées par les Congrès Internationaux de Zoologie. International Rules of Zoological Nomenclature. Internationale Regeln der Zoologischen Nomenklatur. - Paris (Rudeval) * ^ pp. V-VI in Kraus, O. 1962. Internationale Regeln für die Zoologische Nomenklatur. Beschlossen vom XV. Internationalen Kongress für Zoologie. - pp. I-VIII , 1-90. Frankfurt am Main. (Senckenbergische Naturforschende Gesellschaft). * ^ ICZN Code Art. 77.2 * ^ ICZN Constitution Art. 16.2 * ^ French Code online * ^ ICZN Code Art. 86.2 * ^ " Opinion 2027 (Case 3010): Usage of 17 specific names based on wild species that are pre-dated by, or contemporary with, those based on domestic animals (Lepidoptera, Osteichthyes, Mammalia)". Bulletin of Zoological Nomenclature. International Commission on Zoological Nomenclature . 60 (1). 31 March 2003. Archived from the original on 21 August 2007. Retrieved 8 October 2008. * ^ International Commission on Zoological Nomenclature (2012). "Amendment of Articles 8, 9, 10, 21 and 78 of the International Code of Zoological Nomenclature to expand and refine methods of publication". ZooKeys. 219: 1–10. doi :10.3897/zookeys.219.3944 . * ^ Scott L. Wing Causes and Consequences of Globally Warm Climates in the Early ... - 2003 No 369 - Page 288 "Following the general practice of naming species after localities by ending with "-ensis," Schnack (2000) proposed to change the name Discorbis duwi to Discorbis duwiensis. However, the International Code of Zoological Nomenclature (Chapter 7 Article 32) does not allow such a change"
* ICZN website * Text of