The International Code of Zoological Nomenclature (ICZN) is a widely accepted

convention Convention may refer to: * Convention (norm), a custom or tradition, a standard of presentation or conduct ** Treaty, an agreement in international law * Convention (meeting), meeting of a (usually large) group of individuals and/or companies in a ...

in zoology that rules the formal

scientific naming In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the

International Commission on Zoological Nomenclature The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries. Orga ...

(which shares the acronym "ICZN"). The rules principally regulate: * How names are correctly established in the frame of

binominal nomenclature In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

* 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 Botanical nomenclature is the formal, scientific naming of plants. It is related to, but distinct from Alpha taxonomy, taxonomy. Plant taxonomy is concerned with grouping and classifying plants; botanical nomenclature then provides names for the ...

. This implies that animals can have the same generic names as plants (e.g. there is a genus ''

Abronia ''Abronia'' may refer to: *Abronia (gens) The gens Abronia was a Roman family during the time of the emperor Augustus. The ''gens'' is known primarily by two persons, the poet Abronius Silo, and his son, who wrote for pantomimes. See also * Lis ...

'' in both animals and 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 Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

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, while species concepts (and thus the definition of species) are arbitrary to some degree, the rules for names are not. The code applies only to names. 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" for the 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 Case law, also used interchangeably with common law, is law that is based on precedents, that is the judicial decisions from previous cases, rather than law based on constitutions, statutes, or regulations. Case law uses the detailed facts of a l ...

. Any dispute is decided first by applying the code directly, and not by reference to precedent. The code is also

retroactive Retroactive may refer to: * ''Retroactive'' (album), an album by Grand Puba * ''Retro-active'', an album by Karizma * '' Retro Active'', an album by Def Leppard * ''Retroactive'' (film), a 1997 movie starring James Belushi and Kylie Travis See ...

retrospective A retrospective (from Latin ''retrospectare'', "look back"), generally, is a look back at events that took place, or works that were produced, in the past. As a noun, ''retrospective'' has specific meanings in medicine, software development, popu ...

, 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 earlier must be evaluated only under the present edition of the code. In cases of disputes a case can be brought to the commission who has the right to publish a final decision.

Principles

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.ICZN Code Glossary
/ref> 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 Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

; together they make a "

binomen In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

". No other rank can have a name composed of two names. Examples: :Species '' Giraffa camelopardalis'' * Subspecies have a name composed of three names, a "trinomen": generic name,

, subspecific name: :Subspecies '' Giraffa camelopardalis rothschildi'' * Taxa at a rank above species have a name composed of one name, a "uninominal name". :Genus '' Giraffa'', family Giraffidae In botanical nomenclature, the equivalent for "binominal nomenclature" is "binary nomenclature" (or sometimes " binomial nomenclature").

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 British Association to consider the rules of zoological nomenclature. Hugh Edwin Strickland wrote the committee's report. Example: :Nunneley 1837 established ''

Limax maculatus ''Limacus maculatus'', the green cellar slug or Irish yellow slug, is a species of slug native to the Caucasus and Black Sea coast. It has also been introduced to a number of northern European countries. In its introduced range the species is of ...

'' (Gastropoda), Wiktor 2001 classified it as a junior synonym of ''

Limax maximus ''Limax maximus'' (literally, "biggest slug"), known by the common names great grey slug and leopard slug, is a species of slug in the family Limacidae, the keeled slugs.Marshall, B. (2014). Limax maximus Linnaeus, 1758. Accessed through: Worl ...

'' Linnaeus, 1758 from S and W Europe. ''Limax maximus'' was established first, so if Wiktor's 2001 classification is accepted, ''Limax maximus'' takes precedence over ''Limax maculatus'' and must be used for the species. 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

) '' Giraffa camelopardalis'' Linnaeus, 1758 also establishes the subspecies name (the trinomen) ''Giraffa camelopardalis camelopardalis'' Linnaeus, 1758. The same applies to the name of a subspecies; this establishes the corresponding species name. 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 270px, '' valid name. Priority is a fundamental principle of modern botanical nomenclature and zoological nomenclature. Essentially, it is the principle of recognising the first valid application of a name to a plant or animal. There are two asp ...

'', 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. Example: Linnaeus 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.

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

first reviser 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 ...

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) The following are not homonyms of ''Argus'': :''

Argua ''Declana'' is a genus of moths in the family Geometridae The geometer moths are moths belonging to the family Geometridae of the insect order Lepidoptera, the moths and butterflies. Their scientific name derives from the Ancient Greek ''geo' ...

'' Walker, 1863 (Lepidoptera), ''

Argusa Argura ( grc, Ἄργουρα), called Argissa (Ἄργισσα) in Homer's ''Iliad'', was a town and polis (city-state) in Pelasgiotis in ancient Thessaly, on the Peneus, and near Larissa. The name of the town was also given as Argusa (Ἆργο ...

'' Kelham, 1888 (Aves), ''

Argusina ''Irdex'' is a genus of earwigs belonging to the family Spongiphoridae Spongiphoridae is a family of little earwigs in the suborder Neodermaptera. There are more than 40 genera and 510 described species in Spongiphoridae. Genera These 43 gene ...

'' Hebard, 1927 (Dermaptera), †''

Arcus Arcus may refer to: Businesses and organizations *ARCUS, the Arctic Research Consortium of the United States, supporting Arctic policy in the U.S. *Arcus AS, a Norwegian producer of liquor * Arcus Co., a Bulgarian firearm manufacturer *Arcus Fou ...

'' Hong, 1983 (Diptera), ''

Argas ''Argas'' is a genus of tick. Species * '' Argas abdussalami'' Hoogstraal & McCarthy, 1965 * '' Argas acinus'' Whittick, 1938 * '' Argas africolumbae'' Hoogstraal, Kaiser, Walker, Ledger, Converse & Rice, 1975 * '' Argas arboreus'' Kaiser, Hoo ...

'' Latreille, 1795 (Araneae), ''

Argulus ''Argulus'' is a genus of fish lice in the family Argulidae The family Argulidae, whose members are commonly known as carp lice or fish lice, are parasitic crustaceans in the class Ichthyostraca. It is the only family in the monotypic subclas ...

'' Müller, 1785 (Crustacea). The following names are not homonyms of each others: :'' Isomya'' Cutler & Cutler, 1985 (Sipunculida), '' Isomyia'' Walker, 1859 (Diptera). :''

Adelomya The speckled hummingbird (''Adelomyia melanogenys''), is a species of hummingbird. It is the only member of the genus ''Adelomyia''. It inhabits Neotropical montane cloud forests at elevations of 1,000–2,500 meters and is confined to the ...

'' Mulsant & Verreaux, 1866 (Aves), '' Adelomyia'' Bonaparte, 1854 (Aves), †'' Adelomys'' Gervais, 1853 (Mammalia), †'' Adolomys'' Shevyreva, 1989 (Mammalia), '' Adulomya'' Kuroda, 1931 (Bivalvia). In species, there is a difference between primary and secondary homonyms. Some spelling variants are explicitly defined by the ''Code'' as being homonyms. Otherwise the one-letter difference rule applies. ''Primary homonyms'' are those with the same genus and same species in their original combination. The difference between a primary junior homonym and a subsequent use of a name is undefined, but it is commonly accepted that if the name referred to another species or form, and if there is in addition no evidence the author knew that the name was previously used, it is considered as a junior homonym. Examples: :Drury (1773) established ''

Cerambyx maculatus ''Stellognatha maculata'' is a species of beetle belonging to the family Cerambycidae. Description ''Stellognatha maculata'' can reach a body length of . The basic colour of these impressive long-horned beetles is blackish, with very long anten ...

'' (Coleoptera) for a species from Jamaica. Fueßlin (1775) established ''

'' for a different species from Switzerland, and did not refer to Drury's name. Fueßlin's name is a junior primary homonym. :Scopoli (1763) established ''

Curculio fasciatus ''Curculio'' is a genus of weevils belonging the family Curculionidae and subfamily Curculioninae. Members of the genus are commonly referred to as acorn weevils or nut weevils as they infest the seeds of trees such as oaks and hickories. The ...

'' (Coleoptera) for a species from Slovenia. Strøm (1768) established ''

'' for another species from Norway. De Geer (1775) established ''

'' for a 3rd species from Sweden. Müller (1776) established ''

'' for a 4th species from Denmark. Fourcroy (1785) established ''

'' for a 5th species from France. Olivier (1790) established ''

'' for a 6th species from France. Marsham (1802) established ''

'' for a 7th species from Britain. All these names had descriptions that clarified that different species were meant, and that their authors did not know that the name had been established by a previous author. ''Secondary homonyms'' can be produced if taxa with the same specific name but different original genus are later classified in the same genus (Art. 57.3, 59). A secondary synonym is only a temporary state, it is only effective in this classification. If another classification is applied, the secondary homonymy may not be produced, and the involved name can be used again (Art. 59.1). A name does not become unavailable or unusable if it was once in the course of history placed in such a genus where it produced a secondary homonymy with another name. This is one of the rare cases where a zoological species does not have a stable specific name and a unique species-author-year combination, it can have two names at the same time. Example: :Nunneley (1837) established ''

'' (Gastropoda), Wiktor (2001) classified it as a junior synonym of '' Limax (Limax) maximus'' Linnaeus, 1758 from S and W Europe. Kaleniczenko, 1851 established ''

Krynickillus maculatus ''Limacus maculatus'', the green cellar slug or Irish yellow slug, is a species of slug native to the Caucasus and Black Sea coast. It has also been introduced to a number of northern European countries. In its introduced range the species is of ...

'' for a different species from Ukraine. Wiktor, 2001 classified both ''Limax maximus'' Linnaeus, 1758 and ''Krynickillus maculatus'' Kaleniczenko, 1851 in the genus '' Limax''. This meant that ''L. maculatus'' Nunneley, 1837 and ''K. maculatus'' Kaleniczenko, 1851 were classified in the same genus, so both names were secondary homonyms in the genus Limax, and the younger name (from 1851) could not be used for the Ukrainian species. This made it necessary to look for the next younger available name that could be used for the Ukrainian species. This was ''

Limax ecarinatus ''Limacus maculatus'', the green cellar slug or Irish yellow slug, is a species of slug native to the Caucasus and Black Sea coast. It has also been introduced to a number of northern European countries. In its introduced range the species is oft ...

'' Boettger, 1881, a junior synonym of ''K. maculatus'' Kaleniczenko, 1851. :For Wiktor (2001) and those authors who follow Wiktor's system the name of the Ukrainian species must be ''

'' Boettger, 1881. For the others who classify ''

Limacus ''Limacus'' is a genus of air-breathing land slugs, terrestrial pulmonate gastropod mollusks in the family Limacidae, the short-keeled slugs. MolluscaBase (2019). MolluscaBase. Limacus Lehmann, 1864. Accessed through: World Register of Marine ...

'' as a separate genus, the name of the Ukrainian species must be ''

Limacus maculatus ''Limacus maculatus'', the green cellar slug or Irish yellow slug, is a species of slug native to the Caucasus and Black Sea coast. It has also been introduced to a number of northern European countries. In its introduced range the species is oft ...

'' (Kaleniczenko, 1851). :So the Ukrainian species can have two names, depending from its generic classification. ''

'', ''

'', the same species. Article 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 A helix () is a shape like a corkscrew or spiral staircase. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, ...

'' allot 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 not homonymy in the strict sense: 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'' Linnaeus, 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'' Linnaeus, 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 ''Erebus caprimulgus'' is a moth of the family Erebidae. It is found from the Oriental Region of India, Sri Lanka, Myanmar to Peninsular Malaysia, Sumatra and Borneo Borneo (; id, Kalimantan) is the third-largest island in the world a ...

'' Fabricius, 1775 (Lepidoptera), thus creating a double homonym. Double homonymy is no homonymy, both names are available. :The same happened with ''

Noctua variegata The New Ireland boobook (''Ninox variegata'') also known as the Bismarck hawk-owl or Bismarck boobook, is a small to medium-sized owl measuring in length. It is a dark rufous-brown above, with barred scapular feathers and variable amounts of spo ...

'' Jung, 1792 (Lepidoptera) and ''

'' 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. Examples: : '' Echidna'' Forster, 1777 (Actinopterygii), not '' Echidna'' Cuvier, 1797 (Mammalia) : '' Ansa'' Walker, 1858 (Lepidoptera), not ''Ansa'' Walker, 1868 (Hemiptera) : ''

Helix balcanica A helix () is a shape like a corkscrew or spiral staircase. It is a type of smoothness (mathematics), smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as ...

'' Kobelt, 1876, not ''

'' Kobelt, 1903 (both Gastropoda) : ''

Conus catenatus ''Conus'' is a genus of predatory sea snails, or cone snails, marine gastropod mollusks in the family Conidae.Bouchet, P.; Gofas, S. (2015). Conus Linnaeus, 1758. In: MolluscaBase (2015). Accessed through: World Register of Marine Species at h ...

'' Sowerby, 1850, not ''

'' Sowerby, 1875 (both Gastropoda) 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 is 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 ''Betousa'' is a monotypic moth genus of the family Crambidae described by Francis Walker in 1865. Its only species, ''Betousa dilecta'', was described by the same author in the same year. It is found on the Moluccas, Retrieved April 19, 2018. Wo ...

'' Walker, 1865 (Lepidoptera: Thyridae) (p. 1111), not ''

'' Walker, 1865 (Lepidoptera: Noctuidae) (p. 1208). :''

Cicada variegata The cicadas () are a superfamily, the Cicadoidea, of insects in the order Hemiptera (true bugs). They are in the suborder Auchenorrhyncha, along with smaller jumping bugs such as leafhoppers and froghoppers. The superfamily is divided into two ...

'' Fabricius, 1775 (p. 684), not ''

'' Fabricius, 1775 (p. 686) (both Auchenorrhyncha). :''

Noctua marginata ''Catocala epione'', the Epione underwing, is a moth of the family Erebidae. The species was first described by Dru Drury in 1773. It is found in North America from Quebec and Ontario south through Connecticut to Florida and west to Texas and O ...

'' Fabricius, 1775 (p. 597), not ''

'' 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 homonym the expression "hemihomonym" 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

Gastropoda The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. ...

, but the name is also (rarely) used for a group in

Arachnida Arachnida () is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegaroon ...

. : Reticulata is used as an order in Foraminifera, and as an undefined higher group in Ephemeroptera. 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 ''Bulimina'' is a genus of foraminifers belonging to the family Buliminidae. The genus has cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the worl ...

'' (Foraminifera) and ''

Buliminus ''Buliminus'', is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Enidae. Species Species within the genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of ...

'' (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 ''

Clarias ''Clarias'' is a genus of catfishes (order Siluriformes) of the family Clariidae, the airbreathing catfishes. The name is derived from the Greek ''chlaros'', which means lively, in reference to the ability of the fish to live for a long time out ...

'' (Actinopterygii) give both Clariidae, but only the actinopterygian fish name was used since 1845. Shortly after Clariidae had been proposed in Rotifera in 1990, the homonymy was discovered and the commission had to decide that the Rotiferan family had to be amended to

Clariaidae Clariaidae is a family of rotifers belonging to the order Ploima Ploima is an order of rotifers, microscopic invertebrates found in marine and freshwater habitats. Families According to the World Register of Marine Species, Ploima includes th ...

(Opinion 2032).

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 articles 67–69. Type species are very important, and no general zoological database has recorded the type species for all genera. Except in fishes and some minor groups, type species are rarely reliably recorded in online animal databases. In 60% of the cases the type species can be determined in the original publication. The type species is always the original name of the taxon (and not the currently used combination). Example: :The correctly cited type species of ''Locusta'' Linnaeus, 1758 (Caelifera) is ''

Gryllus migratorius ''Gryllus'' is a genus of field cricket (Orthoptera, Gryllidae, Gryllinae). Members of the genus are typically 15–31 mm long and darkly coloured. The type species is '' Gryllus campestris'' L.: the European field cricket. Until the mi ...

'' Linnaeus, 1758, not '' Locusta migratoria'' (Linnaeus, 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 (articles 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 Galba (; born Servius Sulpicius Galba; 24 December 3 BC – 15 January AD 69) was the sixth Roman emperor, ruling from AD 68 to 69. After his adoption by his stepmother, and before becoming emperor, he was known as Livius Ocella Sulpicius Ga ...

'' Schrank, 1803 (Gastropoda) was established with one species included, ''

Galba pusilla Galba (; born Servius Sulpicius Galba; 24 December 3 BC – 15 January AD 69) was the sixth Roman emperor, ruling from AD 68 to 69. After his adoption by his stepmother, and before becoming emperor, he was known as Livius Ocella Sulpicius Ga ...

'' Schrank, 1803. This would be the type species by monotypy. In Opinion 1896 (published in 1998) this type fixation was set aside and ''

Buccinum truncatulum ''Buccinum'' is a genus of medium-sized sea snails, marine gastropod molluscs in the family Buccinidae, the true whelks.Gofas, S.; Bouchet, P. (2014). Buccinum Linnaeus, 1758. Accessed through: World Register of Marine Species at http://www. ...

'' Müller, 1774 was fixed as type species under the plenary power(s) (now '' Galba truncatula''). ::Designation under Art. 70.3 (misidentified type species) (1 %) :::Examples: :::''

Bollingeria ''Multidentula'' is a genus of minute air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Enidae Enidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks. MolluscaBase eds. (20 ...

'' Forcart, 1940 (Gastropoda) was established with its type species ''

Chondrus pupoides ''Chondrus'' is a genus of red algae containing 11 accepted species: *''Chondrus armatus'' (Harvey) Okamura *''Chondrus canaliculatus'' (C.Agardh) Greville *''Chondrus crispus'' Stackhouse *''Chondrus elatus'' Holmes *''Chondrus giganteus'' Yend ...

'' Krynicki, 1833 proposed by original designation. But Forcart 1940 misidentified the type species and meant '' Bulimus lamelliferus'' Rossmässler, 1858. It would be convenient to designate '' Bulimus lamelliferus'' as type species under Art. 70.3. :::''

Helisoma ''Helisoma'' is a genus of freshwater air-breathing snail, a pulmonate gastropod mollusk in the family Planorbidae Planorbidae, common name the ramshorn snails or ram's horn snails, is a family of air-breathing freshwater snails, aquatic p ...

'' Swainson, 1840 (Gastropoda) was established with one species included, cited by Swainson as "'' H. bicarinata'' Sow. Gen. f. 4". This suggested that the type species was misidentified, and that ''

Planorbis campanulatus ''Planorbis'' is a genus of air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails, or planorbids. All species in this genus have sinistral or left-coiling shells.Bouchet, P.; Rosen ...

'' Say, 1821 and not ''

Planorbis bicarinatus ''Planorbis'' is a genus of air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails, or planorbids. All species in this genus have sinistral or left-coiling shells.Bouchet, P.; Rose ...

'' Say, 1819 was meant. But since the incorrect type species ''

'' has been regarded as type, it would be convenient to fix this as type under Art. 70.3. * Type fixation in the original work: ::Original designation (31 %) :::Examples: :::Montfort 1810 established the genus '' Theodoxus'' (Gastropoda) and designated ''

Theodoxus lutetianus ''Theodoxus'' is a genus of nerites, small water snails with an operculum, some of which live in freshwater, and some in both freshwater and brackish water, aquatic gastropod mollusks in the family Neritidae, the nerites.Bouchet, P. (2014). Theo ...

'' Montfort 1810 as type species (now ''

Theodoxus fluviatilis ''Theodoxus fluviatilis'', common name the river nerite, is a species of small freshwater and brackish water snail with a gill and an operculum, an aquatic gastropod mollusk in the family Neritidae, the nerites.Neubauer, Thomas A. (2014). ''T ...

''). :::Vest 1867 established the subgenus ''

Clausilia (Isabellaria) ''Clausilia'' is a European genus of small, air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Clausiliidae, the door snails, all of which have a clausilium.Bank, R.; Bouchet, P. (2017). Clausilia Draparnaud, 1805. ...

'' (Gastropoda) and designated ''

Clausilia isabellina ''Clausilia'' is a European genus of small, air-breathing land snails, terrestrial molluscs, terrestrial pulmonate gastropod mollusks in the family Clausiliidae, the door snails, all of which have a clausilium.Bank, R.; Bouchet, P. (2017). Claus ...

'' Pfeiffer, 1842 as type species (now ''

Isabellaria isabellina ''Isabellaria'' is a genus of gastropods belonging to the family Clausiliidae. The species of this genus are found in Mediterranean. Species: *''Isabellaria abyssoclista'' *''Isabellaria almae'' *''Isabellaria bathyclista'' *''Isabellaria cla ...

''). :::Riedel 1987 established the genus ''

Turcozonites ''Turcozonites'' is a genus of gastropods belonging to the family Zonitidae. The species of this genus are found in Eastern Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin ...

'' (Gastropoda) and designated ''

Zonites wandae ''Zonites'' is a genus of mostly small, air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Zonitidae. The genus Zonites, which includes 26 extant species, is distributed in the northeastern Mediterranean area and e ...

'' Riedel, 1982 as type species (now ''

Turcozonites wandae ''Turcozonites'' is a genus of gastropods belonging to the family Zonitidae. The species of this genus are found in Eastern Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin a ...

''). ::Monotypy (28 %) :::Examples: :::''

Anodonta ''Anodonta'' is a genus of freshwater mussels in the family Unionidae, the river mussels. Species Species in this genus include: * ''Anodonta anatina'' Linné, 1758 – duck mussel * '' Anodonta beringiana'' Middendorff, 1851 – Yukon f ...

'' Lamarck, 1799 (Bivalvia) was originally established with one included nominal species, ''

Mytilus cygneus Mytilus may refer to: * Mytilus of Illyria, an ancient Illyrian king * ''Mytilus'' (bivalve), a mollusc genus {{disambig ...

'' Linnaeus, 1758. This is the type species fixed by monotypy (now '' Anodonta cygnea''). :::''

Microcondylaea ''Microcondylaea'' is a genus of freshwater mussels in the family Unionidae The Unionidae are a family of freshwater mussels, the largest in the order Unionida, the bivalve molluscs sometimes known as river mussels, or simply as unionids. ...

'' Vest 1866 (Bivalvia) was originally established with two included nominal species, ''

Unio bonellii Unio may refer to: * ''Unio'' (bivalve), a genus of freshwater mussels * ''Unio'' (sternwheeler), a steamboat that operated in Oregon, United States, in 1861, before being renamed ''Union'' * UNI/O, an asynchronous serial bus * UNIO Satu Mare, a ...

'' Férussac, 1827 and with doubts ''

Anodonta lata ''Anodonta'' is a genus of freshwater mussels in the family Unionidae, the river mussels. Species Species in this genus include: * ''Anodonta anatina'' Linné, 1758 – duck mussel * '' Anodonta beringiana'' Middendorff, 1851 – Yukon f ...

'' Rafinesque, 1820. Doubtfully included species do not count, type species is ''

'' fixed by monotypy (now ''

Microcondylaea bonellii ''Microcondylaea bonellii'' is a species of bivalve belonging to the family Unionidae. The species is endemic to South Europe. ''Microcondylaea bonellii'' is a freshwater bivalve occurring in both rivers and lakes. It is known from Switzerland, ...

''). ::Absolute tautonymy (2 %) :::Examples: :::Kobelt 1871 established the gastropod genus-group name ''

Candidula ''Candidula'' is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Geomitridae, . MolluscaBase eds. (2020). MolluscaBase. Candidula Kobelt, 1871. Accessed through: World Register of Marine Species at ...

'' and included 23 species. Among these was '' Glischrus candidula'' Studer 1820. '' Glischrus candidula'' is type species fixed by absolute tautonymy (now ''

Candidula unifasciata ''Candidula unifasciata'' is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Geomitridae. MolluscaBase eds. (2020). MolluscaBase. Candidula unifasciata (Poiret, 1801). Accessed through: World Regist ...

''). :::Draparnaud 1801 established the gastropod genus ''

Succinea ''Succinea'', common name the amber snails, is a large genus of small, air-breathing land snails, terrestrial pulmonate gastropod molluscs in the family Succineidae. MolluscaBase eds. (2021). MolluscaBase. Succinea Draparnaud, 1801. Access ...

'' and included two species, ''

Succinea amphibia ''Succinea'', common name the amber snails, is a large genus of small, air-breathing land snails, terrestrial pulmonate gastropod molluscs in the family Succineidae. MolluscaBase eds. (2021). MolluscaBase. Succinea Draparnaud, 1801. Access ...

'' Draparnaud 1801 and ''

Succinea oblonga ''Succinella oblonga'' is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Succineidae. MolluscaBase eds. (2022). MolluscaBase. Succinella oblonga (Draparnaud, 1801). Accessed through: World Register ...

'' Draparnaud 1801. Among the synonyms of '' S. amphibia'', Draparnaud listed a name ''

Helix succinea A helix () is a shape like a corkscrew or spiral staircase. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, ...

'' Müller 1774. Synonyms do count here, so ''

'' is type species by absolute tautonymy (now '' Succinea putris''). :::Kobelt 1904 established the gastropod subgenus ''

Iberus (Balearica) ''Iberus'' is a genus of air-breathing land snails, terrestrial molluscs, terrestrial pulmonate gastropod mollusks in the subfamily Helicinae of the family Helicidae. MolluscaBase eds. (2021). MolluscaBase. Iberus Montfort, 1810. Accessed through ...

'' and included 10 species. Among these was ''

Helix balearica A helix () is a shape like a corkscrew or spiral staircase. It is a type of smoothness (mathematics), smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as ...

'' Rossmässler 1838, which Kobelt cited as '' Iberus (Balearica) balearicus''. The ending -us is irrelevant here, ''

'' is type species by absolute tautonymy (currently ''

Iberellus balearicus ''Allognathus'' is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Helicidae, the true snails. The genus is endemic to the Balearic Islands (Western Mediterranean) being present in all major islands an ...

'' or ''

Iberellus hispanicus ''Allognathus'' is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Helicidae, the true snails. The genus is endemic to the Balearic Islands (Western Mediterranean) being present in all major islands an ...

''). :::''

Euxinolauria ''Leiostyla'' is a genus of small air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Lauriidae.Falkner G., Obrdlík P., Castella E. & Speight M. C. D. 2001 ''Shelled Gastropoda of Western Europe''. München: Frie ...

'' Lindholm, 1924 (Gastropoda: Lauriidae) was established as a new replacement name for '' Caucasica'' Caziot & Margier, 1909 (not '' Caucasica'' Boettger, 1877 (Gastropoda: Clausiliidae)). '' Caucasica'' Caziot & Margier, 1909 contained originally four species, among which was ''

Pupa caucasica A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

'' Pfeiffer, 1857. This is the type species for '' Caucasica'' Caziot & Margier, 1909 fixed by absolute tautonymy, and also for ''

'' (now ''

Euxinolauria caucasica ''Leiostyla'' is a genus of small air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Lauriidae.Falkner G., Obrdlík P., Castella E. & Speight M. C. D. 2001 ''Shelled Gastropoda of Western Europe''. München: Friedri ...

''). :::The following examples do not represent absolute tautonymy: '' Scomber scombrus'' Linnaeus, 1758 (Actinopterygii), '' Babyrousa babyrussa'' (Linnaeus, 1758) (Mammalia), ''

Suricata suricatta MeerKAT, originally the Karoo Array Telescope, is a radio telescope consisting of 64 antennas in the Meerkat National Park, in the Northern Cape of South Africa. In 2003, South Africa submitted an expression of interest to host the Square Ki ...

'' (Schreber, 1776) (Mammalia), ''

Merlangius merlangus ''Merlangius merlangus'', commonly known as Whiting or merling, is an important food fish in the eastern North Atlantic Ocean and the northern Mediterranean, western Baltic, and Black Sea. In Anglophonic countries outside the Whiting's natural ...

'' (Linnaeus, 1758) (Actinopterygii), ''

'' (Pfeiffer, 1842) (Gastropoda), ''

Rupestrella rupestris ''Rupestrella'' is a genus of gastropods belonging to the family Chondrinidae. The species of this genus are found in Mediterranean. Species: *'' Rupestrella dupotetii'' *'' Rupestrella homala'' *'' Rupestrella occulta'' *'' Rupestrella phil ...

'' (Philippi, 1836) (Gastropoda). ::Linnean tautonymy (0.3 %) :::Example: :::Linnaeus 1758 established '' Castor'' (Mammalia) and included two species, '' Castor fiber'' and ''

Castor moschatus Castor most commonly refers to: *Castor (star), a star in the Gemini constellation *Castor, one of the Dioscuri/Gemini twins Castor and Pollux in Greco-Roman mythology Castor or CASTOR may also refer to: Science and technology *Castor (rocket s ...

''. Among the synonyms of '' Castor fiber'' was cited the one-word name Castor with references to six pre-Linnean works (Gesner 1598, Rondelet 1554, Jonston 1650, Dodart 1676, Ray 1693 and Aldrovandi 1649). '' Castor fiber'' Linnaeus 1758 is type species fixed by Linnean tautonymy (now '' Castor fiber''). * Subsequent methods of type fixation: ::Subsequent monotypy (2 %) :::Examples: :::'' Valvata'' Müller, 1773 (Gastropoda) was established with a short description and without species. Müller 1774 included one species ''

Valvata cristata ''Valvata cristata'' is a species of minute freshwater snail with an operculum, an aquatic gastropod mollusk or micromollusk in the family Valvatidae ''Valvatidae'', the valve snails, is a taxonomic family of very small freshwater snails ...

'' Müller 1774. ''

'' is type species by subsequent monotypy (now ''

''). :::''

Omphiscola ''Omphiscola'' is a genus of small to medium-sized, air-breathing, freshwater snails, aquatic pulmonate gastropod mollusks in the family Lymnaeidae. Distribution This is a European genus. Species Species within the genus include: * '' Omphi ...

'' Rafinesque, 1819 (Gastropoda) was established without species included. Beck 1837

838 __NOTOC__ Year 838 ( DCCCXXXVIII) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. Events By place Byzantine Empire * July 22 – Battle of Dazimon: Caliph Al-Mu'tasim launches a ma ...

included one species '' Buccinum glabrum'' Müller, 1774. '' Buccinum glabrum'' is type species by subsequent monotypy (now ''

Omphiscola glabra ''Omphiscola glabra'' (Synonym: Stagnicola glaber (O. F. Müller, 1774)) is a species of small to medium-size, air-breathing, freshwater snail, an aquatic pulmonate gastropod mollusk in the family Lymnaeidae.Glöer P. (2002). Überfamilie Lym ...

''). ::Subsequent absolute tautonymy (only very few cases) :::Examples: :::''Alosa Garsault, 1764'' (Actinopterygii) was established without included species. As first author, Cuvier, 1829 included two species ''

Clupea alosa ''Clupea'' is genus of planktivorous bony fish belonging to the family Clupeidae, commonly known as herrings. They are found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Two main ...

'' and ''

Clupea fincta ''Clupea'' is genus of planktivorous bony fish belonging to the family Clupeidae, commonly known as herrings. They are found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Two mai ...

''. Type species is ''

'' Linnaeus 1758 by subsequent absolute tautonymy (now ''

Alosa alosa The allis shad (''Alosa alosa'') is a widespread Northeast Atlantic species of fish in the herring family, Clupeidae. It is an anadromous fish which migrates into fresh water to spawn. It is found in the eastern Atlantic Ocean, the western Ba ...

''). :::''

Rupicapra ''Rupicapra'' is a genus of goat-antelope called the chamois. They belong to the bovine family of hoofed mammals, the Bovidae. Two extant species are recognized. The Apennine chamois (Rupicapra pyrenaica ornata) is a subspecies of the Pyrene ...

'' Garsault, 1764 (Mammalia) was established without included species. As first author, Blainville, 1816 included three species ''

Capra rupicapra Capra may refer to: * Capra (genus), ''Capra'' (genus), comprising the goats * Capra (goat dance), a Romanian custom * Capra (titular see), a titular see in the Catholic Church * Capra (car), a pick-up brand from the Iranian Bahman Group People * ...

'' Linnaeus, 1758, '' Capra pudu'', and ''

Capra americana Capra may refer to: * ''Capra'' (genus), comprising the goats * Capra (goat dance), a Romanian custom * Capra (titular see), a titular see in the Catholic Church * Capra (car), a pick-up brand from the Iranian Bahman Group People * Buzz Capra (b ...

''. Type species is ''

'' by subsequent absolute tautonymy (now ''

Rupicapra rupicapra The chamois (''Rupicapra rupicapra'') or Alpine chamois is a species of goat-antelope native to mountains in Europe, from west to east, including the Alps, the Dinarides, the Tatra and the Carpathian Mountains, the Balkan Mountains, the R ...

''). ::Subsequent Linnean tautonymy (only theoretical, there might be no case) ::Subsequent designation (32 %) :::Examples: :::''

Aplexa ''Aplexa'' is a genus of small, left-handed or sinistral, air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the family Physidae. Shell description These small snails are quite distinctive, because they have shells tha ...

'' Fleming, 1820 (Gastropoda) was established with two species, ''

Bulla hypnorum Bulla (Latin, 'bubble') may refer to: Science and medicine * Bulla (dermatology), a bulla * Bulla, a focal lung pneumatosis, an air pocket in the lung * Auditory bulla, a hollow bony structure on the skull enclosing the ear * Ethmoid bulla, ...

'' Linnaeus, 1758 and ''

Bulla rivalis Bulla (Latin, 'bubble') may refer to: Science and medicine * Bulla (dermatology), a bulla * Bulla, a focal lung pneumatosis, an air pocket in the lung * Auditory bulla, a hollow bony structure on the skull enclosing the ear * Ethmoid bulla, pa ...

'' Turton, 1807. Herrmannsen 1846 fixed ''

'' as type by subsequent designation (now ''

Aplexa hypnorum ''Aplexa hypnorum'', or by the common name, the moss bladder snail, is a species of small air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Physidae, a family which are sometimes known as the bladder snails. ...

''). :::''

Pseudanodonta ''Pseudanodonta'' is a genus of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. MolluscaBase eds. (2021). MolluscaBase. Pseudanodonta Bourguignat, 1877. Accessed through: World Register of Marine Speci ...

'' Bourguignat 1877 (Bivalvia) was established with seven species, ''

Anodonta complanata ''Anodonta'' is a genus of freshwater mussels in the family Unionidae, the river mussels. Species Species in this genus include: * '' Anodonta anatina'' Linné, 1758 – duck mussel * ''Anodonta beringiana'' Middendorff, 1851 – Yukon ...

'' Rossmässler 1835, and six others. Westerlund 1902 validly designated ''

'' as type species (now'' Pseudanodonta complanata''). A ''species-group name'' can have a name-bearing type specimen, but this is not a requirement. In many cases species-group names have no type specimens, or they are lost. In those cases the application of the species-group name is usually based on common acceptance. If there is no common acceptance, there are provisions in the Code to fix a name-bearing type specimen that is binding for users of that name. Fixing such a name-bearing type should only be done if this is taxonomically necessary (articles 74.7.3, 75.2, 75.3). Examples: : ''

Aptenodytes patagonica The genus ''Aptenodytes'' contains two extant species of penguins collectively known as "the great penguins". Etymology The name "Aptenodytes" is a composite of Ancient Greek elements, "ἀ-πτηνο-δύτης" (without-wings-diver). Taxon ...

'' Miller, 1778 is either based on a type specimen, perhaps deposited in the Natural History Museum London or somewhere else, or its type is lost. This is now irrelevant because the usage of the name (as ''

Aptenodytes patagonicus The king penguin (''Aptenodytes patagonicus'') is the second largest species of penguin, smaller, but somewhat similar in appearance to the emperor penguin. There are two subspecies: ''A. p. patagonicus'' and ''A. p. halli''; ''patagonicus'' ...

'') for the king penguin is unambiguously accepted. : The name-bearing type for '' Homo sapiens'' Linnaeus, 1758 is deposited in Uppsala (the bones of Carl von Linné). This is a lectotype designated by Stearn 1959, correctly but unnecessarily because the usage of the name was unambiguous at that time, and still is.

Structure

The code divides names in the following manner: * Names above the family group * Family-group names * Genus-group names * Species-group names The names above the family group are regulated only as to the requirements for publication; there is no restriction to the number of ranks and the use of names is not restricted by priority. 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 In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...

''. The species group has only two ranks: '' species'' and ''

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

''.

Gender agreement

In the species group ''gender agreement'' applies. The name of a species, in two parts, a

, say, ''

Loxodonta africana The African bush elephant (''Loxodonta africana'') is one of two extant African elephant species and one of three extant elephant species. It is the largest living terrestrial animal, with bulls reaching a shoulder height of up to and a body ...

'', and of a subspecies, in three parts, a trinomen, say ''

Canis lupus albus The tundra wolf (''Canis lupus albus''), also known as the Turukhan wolf,Mech, L. David (1981), The Wolf: The Ecology and Behaviour of an Endangered Species', University of Minnesota Press, p. 353, is a subspecies of grey wolf native to Eurasia ...

'', is in the form of a Latin phrase, and must be grammatically correct Latin. If the second part, the

(or the third part, the subspecific name) is adjectival in nature, its ending must agree in gender with the name of the genus. If it is a noun, or an arbitrary combination of letters, this does not apply. * For instance, the generic name ''

Equus Equus may refer to: * ''Equus'' (genus), a genus of animals including horses, donkeys and zebras * ''Equus'' (play), a play by Peter Shaffer * ''Equus'' (film), a film adaptation of the Peter Shaffer play * Equus (comics), a comic book characte ...

'' is masculine; in the name " Equus africanus," the specific name ''africanus'' is an adjective and its ending follows the gender of the generic name. * In ''

Equus zebra The mountain zebra (''Equus zebra'') is a zebra species in the family Equidae, native to southwestern Africa. There are two subspecies, the Cape mountain zebra (''E. z. zebra'') found in South Africa and Hartmann's mountain zebra (''E. z. hartm ...

'' the specific name ''zebra'' is a noun, it may not be "corrected" to "Equus zebrus". * In ''

Equus quagga burchellii Burchell's zebra (''Equus quagga burchellii'') is a southern subspecies of the plains zebra. It is named after the British explorer and naturalist William John Burchell. Common names include bontequagga, Damaraland zebra, and Zululand zebra (Gray ...

'' the subspecific name ''burchellii'' is a noun in the genitive case ("of Burchell"). 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).

History

Written nomenclatural rules in zoology were compiled in various countries since the late 1830s, such as Merton's Rules and Strickland's codes going back to 1843. At the first and second International Zoological Congresses (Paris 1889, Moscow 1892) zoologists saw the need to establish commonly accepted international rules for all disciplines and countries to replace conventions and unwritten rules that varied across disciplines, countries, and languages. Compiling "International Rules on Zoological Nomenclature" was first proposed in 1895 in Leiden (3rd International Congress for Zoology) and officially published in three languages in 1905 (French, English, German; only French was official). From then on, amendments and modifications were subsequently passed by various zoological congresses (Boston 1907, Graz 1910, Monaco 1913, Budapest 1927, Padua 1930, Paris 1948, Copenhagen 1953, and London 1958). These were only published in English, and can only be found in the reports of these congresses or other official publications. 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 second 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 third edition of the code came out in 1985. The present edition is the 4th edition, effective since 2000. These code editions were elaborated on by editorial committees appointed by the

. The ICZN Commission takes its power from a general biological congress (IUBS, International Union of Biological Sciences). The editorial committee for the fourth 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 fourth 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.

Commission

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

, acting on behalf of all zoologists. The commission takes such action in response to proposals submitted to it. * Carl Linnaeus named the

domestic cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members o ...

''Felis catus'' in 1758;

Johann Christian Daniel von Schreber Johann Christian Daniel von Schreber (17 January 1739 in Weißensee, Thuringia – 10 December 1810 in Erlangen), often styled J.C.D. von Schreber, was a German naturalist. Career He was appointed professor of'' materia medica'' at the Univers ...

named the wildcat ''Felis silvestris'' in 1775. For taxonomists who consider these two kinds of cat a single species the

means that the species ought to be named ''F. catus'', but in practice almost all biologists have used ''F. silvestris''. In 2003, the commission issued a ruling (

Opinion 2027 Opinion 2027 is a 2003 ruling of the International Commission on Zoological Nomenclature (ICZN) concerning the conservation of 17 species names of wild animals with domestic derivatives. Opinion 2027 is in response to Case 3010 and subsequent comm ...

) that "conserved the usage of 17 specific names based on wild species, which are pre-dated, by or contemporary with those based on domestic forms", confirming ''F. silvestris'' for the wild cat. Taxonomists who consider the domesticated cat the same species as the wild cat should use ''F. silvestris''; taxonomists who consider the domesticated cat a subspecies of the wild cat should use ''F. silvestris catus''; taxonomists who consider the domesticated cat a separate species should use ''F. catus''. The latest amendments enacted by the commission concern electronic publishing, which is now permitted for works published under an ISBN or ISSN after 2011 in a way that ensures registration with ZooBank as well as archival of multiple copies.

Local usage and name changes

The ICZN is used by the scientific community worldwide. Changes are governed by guidelines in the code.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 ''Discorbis'' is a genus of benthic Foraminifera (Kingdom Protista in paleontological classifications), that made its first appearance during the Eocene. Its present distribution is cosmopolitan. ''Discorbis'' produces a smooth plano-convex to u ...

to Discorbis duwiensis. However, the International Code of Zoological Nomenclature (Chapter 7 Article 32) does not allow such a change" Local changes, such as the changes proposed by the Turkish government, are not recognised by ICZN.

Citation

The current (fourth edition) code is 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.

Versions

* Strickland, H.E. t al.1843. Report of a committee appointed "to consider of the rules by which the Nomenclature of Zoology may be established on a Uniform and Permanent Basis." The Strickland Code".In: ''Report of 12th Meeting of the British Association for the Advancement of Science'', June 1842, p. 105-121
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lso published in the ''Philosophical Magazine'' and the ''Annals of Natural History''.* Strickland, H.E. 1878. ''Rules for Zoological Nomenclature''. John Murray, London
Internet Archive
* 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''. Rudeval, Paris
Google Books
* ICZN. 1961. ''International Code of Zoological Nomenclature: adopted by the XV International Congress of Zoology''. The International Trust for Zoological Nomenclature, London, UK
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* ICZN. 1964. ''International Code of Zoological Nomenclature''. Second edition. The International Trust for Zoological Nomenclature, London, UK
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* ICZN. 1985. ''International Code of Zoological Nomenclature''. Third edition. The International Trust for Zoological Nomenclature, London, UK
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* ICZN. 1999. ''International Code of Zoological Nomenclature''. Fourth edition. The International Trust for Zoological Nomenclature, London, UK.
BHLThe Code Online (ICZN)

Notes

References

External links

ICZN website

Current text of the code

Code-1, Stoll et al. 1961

Code-2, Stoll et al. 1964

Code-3, Ride et al. 1985

Code-4, Ride et al. 2000

ZooBank: The World Register of Animal Names

Proposed amendment of the International Code of Zoological Nomenclature to expand and refine methods of publication
{{Carl Linnaeus * Nomenclature codes