International Code of Zoological Nomenclature
Encyclopedia
The International Code of Zoological Nomenclature (ICZN or ICZN Code) is a widely accepted convention
in zoology
that rules the formal scientific naming of organisms treated as animal
s. The rules principally regulate:
The Code was first published in 1905, although it has precedents such as Merton's Rules and Strickland's codes going back to 1843. The 1st edition was first proposed in 1895 in Leiden (3rd International Congress for Zoology) and published in three languages in 1905 (French, English, German; only French was official). The 2nd edition was from 1961, the 3rd edition from 1985, the present edition is the 4th edition (effective since 2000). The Code is elaborated by the Editorial Committee and issued by the International Commission on Zoological Nomenclature
. The Editorial Committee for the 4th edition was composed of seven persons appointed by the Commission. 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. Currently the Code consists of the original text 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 Code deals with zoological nomenclature, which is defined in the Glossary as
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 an entity to be recognized 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" 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 rank
s. The Code recognizes no case law
. Any dispute is to be 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 are to 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.
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 (a "binomen
"). No other rank can have a name composed of two names. Example:
In botanical nomenclature, the equivalent for "binominal nomenclature" is "binary nomenclature" (or sometimes "binomial nomenclature").
, the name that is to be used, called the valid name
, is the oldest available name
that applies to it.
It is certainly the most important principle and the fundamental guiding precept that preserves the stability of zoological nomenclature. It was first formulated in 1842 by a committee appointed by the British Association to consider the rules of zoological nomenclature; the committee's report was written by Hugh Edwin Strickland
.
Example:
There are approximately 2-3 million cases of this kind for which this Principle is applied in zoology.
In other words, the act of publishing a new zoological name thereby automatically and simultaneously establishes all the corresponding names in the relevant other ranks, with the same type.
In the species-group, publishing a species name (the binomen
) 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.
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, makes a choice and publishes the decision in the required manner, the First Reviser, is to be followed.
Example:
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, currently both names Ph. macrocephalus and Ph. catodon are used.
It means that any one animal name, in one particular spelling, may be used only once (within its group). This will usually be 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 can either be homonyms or not. A one-letter difference is not tolerated.
Examples:
In species there is a difference between primary and secondary homonyms. There can also be double homonyms (same genus and species). A slight difference in spelling is tolerated if Art. 58 applies.
Primary homonyms are those which have the same genus and the 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:
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:
Art. 59.3 states that in exceptional cases junior secondary homonyms which were replaced before 1961 by substitute names can become invalid "unless the substitute name is not in use", an exception of the exception. But 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 is also undefined what the expression "is not in use" should mean.
Example:
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:
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:
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 on which the name was established.
There are cases where two homonyms were established by the same author in the same year on the same page:
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 for animals and plants at the same time. For this kind of homonyms the expression "hemihomonyms" is sometimes used. Far more than 1000 such names are known.
Examples:
For names above the family level, the Principle of Homonymy does not apply.
Examples:
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:
This means that any named taxon
would have 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 type species
for a genus-group name is more complicated and follows exactly defined provisions in Art. 67-69.
Type species are very important, and there is no general zoological database that 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:
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 will always be 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:
A species-group name can have a name-bearing type specimen, but this is no must. 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 which will be binding for the users of that name. Fixing such a name-bearing type should only be done if this is taxonomically necessary (Art. 74.7.3, 75.2, 75.3).
Examples:
Links to the separate articles (these are redundant and can eventually be removed):
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 group, the genus group and the species group are fully regulated by the provisions in the Code. There is no limitation to the number of ranks allowed in the family group. In the genus group there are only two ranks: the genus
and the subgenus
. In the species group there are only two ranks: the species
and the subspecies
.
, say, Loxodonta africana, and of a subspecies, in three parts, a trinomen
, say Canis lupus albus, originally is a Latin phrase, and must be grammatically correct Latin. If the second part, the specific name (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 combinations of letters, this does not apply.
If a species is moved, therefore, the spelling of an ending may need to be changed. If Gryllus migratorius is moved to the genus Locusta
, it becomes Locusta migratoria. Confusion over proper Latin grammar have led to many incorrectly formed names appearing in print. An improper 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).
Accordingly, many laymen and some scientists object to continued adherence to this rule, especially those who work with butterflies and moths
. This has historical reasons. In 1758, Linnæus placed all butterflies in the genus Papilio
, which after a few decades contained thousands of species. From the beginning on the gender of Papilio was unclear, undecided and disputed. Some authors regarded it as masculine, others as feminine. Linnæus knew this problem and avoided any statement. All his 250 specific names in the genus Papilio were either nouns, unchangeable adjectives or adjectives ending in -is. He strictly did not use a single adjective ending in -us, -a, -um. P. Brown, Cramer
, Fabricius
, Fueßlin
, Goeze
, Poda
and Schrank regarded Papilio as masculine, Ménétriés
, Pontoppidan
and most modern authors as feminine. In ICZN Opinion 278 from 1954 it was regarded as masculine. In many cases lepidopterists would not change the ending of a name as used by the author who established a name. So we find for example Papilio fuscus
or Papilio macilentus
, but also Papilio osmana
and Papilio paradoxa. Only in few cases both versions are found in the web (an example is Papilio multicaudatus and Papilio multicaudata). This works also with other butterfly genera of which the gender is undisputed. Graphium
is clearly neuter, but only the incorrect versions Graphium angolanus
and Graphium mandarinus are used, while Graphium sandawanum can only be found in the correct declination. Likewise pairs are more frequently found in genera of which the gender is not obvious: Delias castaneus and Delias gigantea, Belenois albumaculatus and Belenois rubrosignata, Mylothris arabicus and Mylothris ruandana. Even in moths such pairs can be found: Xylophanes obscurus
and Xylophanes turbata
, Manduca boliviana
and Manduca caribbeus
, Sphinx caligineus
and Sphinx formosana
, Macroglossum albolineata
and Macroglossum vicinum
. It may also occur that a lepidopteran subspecies
can have a different gender than the name of the species
, as for example in Papilio multicaudata pusillus Austin & Emmel, 1998, or Papilio torquatus flavida Oberthür, 1879.
, acting on behalf of all zoologists. The Commission takes such action in response to proposals submitted to it.
Convention (norm)
A convention is a set of agreed, stipulated or generally accepted standards, norms, social norms or criteria, often taking the form of a custom....
in zoology
Zoology
Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...
that rules the formal scientific naming of organisms treated as animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
s. The rules principally regulate:
- how names are correctly established in the frame of binominal nomenclature,
- which name has to be used in case of conflicts among various names,
- how names are to be cited in the scientific literature.
The Code was first published in 1905, although it has precedents such as Merton's Rules and Strickland's codes going back to 1843. The 1st edition was first proposed in 1895 in Leiden (3rd International Congress for Zoology) and published in three languages in 1905 (French, English, German; only French was official). The 2nd edition was from 1961, the 3rd edition from 1985, the present edition is the 4th edition (effective since 2000). The Code is elaborated by the Editorial Committee and issued by the International Commission on Zoological Nomenclature
International Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 28 members from 20 countries, mainly practicing zoological taxonomists...
. The Editorial Committee for the 4th edition was composed of seven persons appointed by the Commission. 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. Currently the Code consists of the original text 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 Code deals with zoological nomenclature, which is defined in the Glossary as
- "The system of scientific names for animal taxa and the provisions for the formation, treatment, and use of those names."
Zoological nomenclature is independent of other systems of nomenclature, for example botanical nomenclature
Botanical nomenclature
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...
. 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
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
judgment dictates otherwise. The Code is meant to guide only the nomenclature of animals, while leaving zoologists freedom in classifying new taxa
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
. In other words, whether a species itself is or is not an entity to be recognized 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" for the Loch Ness Monster
Loch Ness Monster
The Loch Ness Monster is a cryptid that is reputed to inhabit Loch Ness in the Scottish Highlands. It is similar to other supposed lake monsters in Scotland and elsewhere, though its description varies from one account to the next....
).
The rules in the Code determine what names are valid for any taxon in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
group, genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
group, and species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
group. It has additional (but more limited) provisions on names in higher rank
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
s. The Code recognizes no case law
Case law
In law, case law is the set of reported judicial decisions of selected appellate courts and other courts of first instance which make new interpretations of the law and, therefore, can be cited as precedents in a process known as stare decisis...
. Any dispute is to be decided first by applying the Code directly, and not by reference to precedent. The Code is also retroactive or retrospective
Retrospective
Retrospective generally means to take a look back at events that already have taken place. For example, the term is used in medicine, describing a look back at a patient's medical history or lifestyle.-Music:...
, 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 are to 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.
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.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 (a "binomen
Binomen
In zoological nomenclature, a binomen , is the two-part name of a species. The term was introduced in 1953, abolishing the previously used "binomial name" . A binomen consists of a generic name and a specific epithet...
"). No other rank can have a name composed of two names. Example:
- Species Giraffa camelopardalis
- Subspecies have a name composed of three names, a "trinomenTrinomenIn zoological nomenclature, a trinomen , or trinominal name, refers to the name of a subspecies.A trinomen is a name consisting of three names: generic name, specific name and subspecific name. The first two parts alone form the binomen or species name. All three names are typeset in italics, and...
": generic name, specific name, subspecific nameSubspecific nameIn zoological nomenclature, a subspecific name is the third part of a trinomen. In zoology there is only one rank below that of species, namely "subspecies"....
:
- Subspecies have a name composed of three names, a "trinomen
- Subspecies Giraffa camelopardalis rothschildi
- Taxa at a rank above species have a name composed of one name, a "uninominal name".
- Genus GiraffaGiraffaGiraffa is a genus of mammals in the Giraffidae family. The genus consists of seven species including the giraffe, Giraffa camelopardalis, the only extant species.- Species :There are six species in the genus Giraffa....
, familiy GiraffidaeGiraffidaeThe giraffids are ruminant artiodactyl mammals that share a common ancestor with deer and bovids. The biological family Giraffidae, once a diverse group spread throughout Eurasia and Africa, contains only two living members, the giraffe and the okapi. Both are confined to sub-saharan Africa: the...
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 taxonTaxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
, the name that is to be used, called the valid name
Valid name (zoology)
In zoological nomenclature, the valid name of a taxon is the zoological name that is to be used for that taxon following the rules in the International Code of Zoological Nomenclature . In other words: a valid name is the correct zoological name of a taxon.In contrast, an invalid name is a name...
, is the oldest available name
Available name
In zoology, an available name is a scientific name for a taxon of animals that has been published conforming to all the mandatory provisions of the ICZN Code for the establishment of a zoological name....
that applies to it.
It is certainly the most important principle and the fundamental guiding precept that preserves the stability of zoological nomenclature. It was first formulated in 1842 by a committee appointed by the British Association to consider the rules of zoological nomenclature; the committee's report was written by Hugh Edwin Strickland
Hugh Edwin Strickland
Hugh Edwin Strickland , was an English geologist, ornithologist,naturalist, and systematist.Strickland was born at Reighton, in the East Riding of Yorkshire. He was the second son of Henry Eustatius Strickland of Apperley, Gloucestershire, by his wife Mary, daughter of Edmund Cartwright, D.D. [q...
.
Example:
- Nunneley 1837 established Limax maculatusLimax maculatusLimax ecarinatus , is a large species of air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Limacidae....
(Gastropoda), Wiktor 2001 classified it as a junior synonym of Limax maximus Linnæus 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 has to 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
This is the principle that within the family group, genus group and species group a name established for a taxon at any rank in the group is deemed to be simultaneously established with the same author and date for taxa based on the same name-bearing type at other ranks in the corresponding group.In other words, the act of publishing a new zoological name thereby automatically and simultaneously establishes all the corresponding names in the relevant other ranks, with the same type.
In the species-group, publishing a species name (the binomen
Binomen
In zoological nomenclature, a binomen , is the two-part name of a species. The term was introduced in 1953, abolishing the previously used "binomial name" . A binomen consists of a generic name and a specific epithet...
) Giraffa camelopardalis Linnaeus, 1758 also establishes the subspecies name (the trinomen
Trinomen
In zoological nomenclature, a trinomen , or trinominal name, refers to the name of a subspecies.A trinomen is a name consisting of three names: generic name, specific name and subspecific name. The first two parts alone form the binomen or species name. All three names are typeset in italics, and...
) 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
Giraffa
Giraffa is a genus of mammals in the Giraffidae family. The genus consists of seven species including the giraffe, Giraffa camelopardalis, the only extant species.- Species :There are six species in the genus Giraffa....
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
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
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 one shall be regarded as the one that should have precedence.It supplements the Principle of Priority
Principle of Priority
thumb|270px|Boa manditraIn zoology, the scientific study of animals, the Principle of Priority is one of the guiding principles of the International Code of Zoological Nomenclature, defined by Article 23....
, 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
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
, 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, makes a choice and publishes the decision in the required manner, the First Reviser, is to be followed.
Example:
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
Snowy Owl
The Snowy Owl is a large owl of the typical owl family Strigidae. The Snowy Owl was first classified in 1758 by Carolus Linnaeus, the Swedish naturalist who developed binomial nomenclature to classify and organize plants and animals. The bird is also known in North America as the Arctic Owl, Great...
. 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
Sperm Whale
The sperm whale, Physeter macrocephalus, is a marine mammal species, order Cetacea, a toothed whale having the largest brain of any animal. The name comes from the milky-white waxy substance, spermaceti, found in the animal's head. The sperm whale is the only living member of genus Physeter...
Linnæus 1758 established three subjective synonyms, Physeter macrocephalus, Physeter catodon and Physeter microps. The First Reviser remains unknown, currently both names 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 will usually be the first-published name; any later name with the same spelling (a homonym
Homonym (zoology)
In biology, a homonym is a name for a taxon that is identical in spelling to another such name, that belongs to a different taxon.The rule in the International Code of Zoological Nomenclature is that the first such name to be published is the senior homonym and is to be used ; any others are junior...
) is barred from being used. The Principles of Priority
Principle of Priority
thumb|270px|Boa manditraIn zoology, the scientific study of animals, the Principle of Priority is one of the guiding principles of the International Code of Zoological Nomenclature, defined by Article 23....
and the First Reviser
Principle of the First Reviser
In zoology, the Principle of the First Reviser is one of the guiding principles of the International Code of Zoological Nomenclature.It supplements the Principle of Priority, which states that the first published name takes precedence...
apply here. For family-group names the termination (which is rank-bound) is not taken into account.
Genera can either be homonyms or not. A one-letter difference is not tolerated.
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:
- Argua Walker 1863 (Lepidoptera), Argusa Kelham 1888 (Aves), Argusina Hebard 1927 (Dermaptera), ArcusArcusArcus may mean:*Arcus AS, a Norwegian producer of liquor*Arcus cloud, a low, horizontal cloud formation*Arcus Foundation, a foundation that envisions and contributes to a pluralistic world that celebrates diversity and dignity, invests in social justice, and promotes tolerance and compassion*Arcus...
Hong 1983 (Diptera), ArgasArgasArgas is a genus of tick.-Species:* Argas abdussalami Hoogstraal & McCarthy, 1965* Argas acinus Whittick, 1938* Argas africolumbae Hoogstraal, Kaiser, Walker, Ledger, Converse & Rice, 1975...
Latreille 1795 (Araneae), Argulus Müller 1785 (Crustacea).
- Homonyms are not: Isomya Cutler & Cutler 1985 (Sipunculida), Isomyia Walker 1859 (Diptera).
- Homonyms are not: Adelomya 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. There can also be double homonyms (same genus and species). A slight difference in spelling is tolerated if Art. 58 applies.
Primary homonyms are those which have the same genus and the 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 (Coleoptera) for a species from JamaicaJamaicaJamaica is an island nation of the Greater Antilles, in length, up to in width and 10,990 square kilometres in area. It is situated in the Caribbean Sea, about south of Cuba, and west of Hispaniola, the island harbouring the nation-states Haiti and the Dominican Republic...
. Fueßlin 1775 established Cerambyx maculatus 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 (Coleoptera) for a species from Slovenia. Strøm 1768 established Curculio fasciatus for another species from Norway. De Geer 1775 established Curculio fasciatus for a 3rd species from Sweden. Müller 1776 established Curculio fasciatus for a 4th species from Denmark. Fourcroy 1785 established Curculio fasciatus for a 5th species from France. Olivier 1790 established Curculio fasciatus for a 6th species from France. Marsham 1802 established Curculio fasciatus for a 7th species from Britain. All these names had descriptions which made clear that different species were meant, and that their authors had not known 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 Limax maculatusLimax maculatusLimax ecarinatus , is a large species of air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Limacidae....
(Gastropoda), Wiktor 2001 classified it as a junior synonym of Limax (Limax) maximus Linnæus 1758 from S and W Europe. Kaleniczenko 1851 established Krynickillus maculatus for a different species from Ukraine. Wiktor 2001 classified both Limax maximus Linnæus, 1758 and Krynickillus maculatus Kaleniczenko, 1851 in the genus LimaxLimaxLimax is a genus of air-breathing land slugs, terrestrial pulmonate gastropod mollusks in the family Limacidae.The generic name Limax literally means "slug"....
. 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 LimaxLimaxLimax is a genus of air-breathing land slugs, terrestrial pulmonate gastropod mollusks in the family Limacidae.The generic name Limax literally means "slug"....
, 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 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 Limax ecarinatus Boettger 1881. For the others who classify LimacusLimacusLimacus is a subgenus of air-breathing land slugs, terrestrial pulmonate gastropod mollusks in the family Limacidae, the keelback slugs.Limacus is considered as a subgenus of the genus Limax.-Species:Species within this subgenus include:...
as a separate genus, the name of the Ukrainian species must be Limacus maculatus (Kaleniczenko 1851). - So the Ukrainian species can have two names, depending from its generic classification. Limax ecarinatus, Limacus maculatus, the same species.
Art. 59.3 states that in exceptional cases junior secondary homonyms which were replaced before 1961 by substitute names can become invalid "unless the substitute name is not in use", an exception of the exception. But 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 is also undefined what the expression "is not in use" should mean.
Example:
- Glischrus caelata Studer, 1820 (Gastropoda) was once classified in the genus HelixHelixA helix is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helixes are coil springs and the handrails of spiral staircases. A "filled-in" helix – for...
, and became a junior secondary homonym of Helix caelata [Vallot], 1801. Locard 1880 established a replacement name Helix glypta, which has very rarely been used. The species is currently 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 NoctuaNoctuaNoctua was a seldom mentioned constellation that was once placed between the end of the tail of Hydra, the sea-serpent and Libra. The origins of the constellation are unknown, but an image of it appears in the American astronomer Elijah Burritt's Atlas , part of his Geography of the Heavens...
Linnæus 1758 was established for a lepidopteran subgenus. In 1764 he established a genus NoctuaNoctuaNoctua was a seldom mentioned constellation that was once placed between the end of the tail of Hydra, the sea-serpent and Libra. The origins of the constellation are unknown, but an image of it appears in the American astronomer Elijah Burritt's Atlas , part of his Geography of the Heavens...
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 used 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.
Examples:
- EchidnaMoray eelMoray eels are cosmopolitan eels of the family Muraenidae. The approximately 200 species in 15 genera are almost exclusively marine, but several species are regularly seen in brackish water and a few, for example the freshwater moray can sometimes be found in freshwater...
Forster, 1777 (Actinopterygii), not EchidnaEchidnaEchidnas , also known as spiny anteaters, belong to the family Tachyglossidae in the monotreme order of egg-laying mammals. There are four extant species, which, together with the platypus, are the only surviving members of that order and are the only extant mammals that lay eggs...
Cuvier, 1797 (Mammalia) - AnsaAnsa (moth)Ansa is a genus of moths of the Noctuidae family.-References:*...
Walker, 1858 (Lepidoptera), not Ansa Walker, 1868 (Hemiptera) - Helix balcanica Kobelt, 1876, not Helix balcanica Kobelt, 1903 (both Gastropoda)
- Conus catenatus Sowerby, 1850, not Conus catenatus 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 would be useful to cite the page on which the name was established.
- Amydona Walker 1855 (Lepidoptera: Limacodidae) (p. 1110), not Amydona Walker 1855 (Lepidoptera: Lasiocampidae) (p. 1413)
- BetousaBetousaBetousa is a genus of moths of the Crambidae family.-Species:*Betousa aspirans Warren, 1899*Betousa dilecta Walker, 1865...
Walker 1865 (Lepidoptera: Thyridae) (p. 1111), not BetousaBetousaBetousa is a genus of moths of the Crambidae family.-Species:*Betousa aspirans Warren, 1899*Betousa dilecta Walker, 1865...
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
Biodiversity Informatics
Biodiversity Informatics is the application of informatics techniques to biodiversity information for improved management, presentation, discovery, exploration and analysis...
) is that the same generic name can be used for animals and plants at the same time. For this kind of homonyms the expression "hemihomonyms" is sometimes used. Far more than 1000 such names are known.
Examples:
- The generic name DryasDryas (plant)Dryas is a genus of dwarf perennial herbaceous plants in the rose family Rosaceae, native to the arctic and alpine regions of Europe, Asia and North America. The genus is named after the Greek nymph Dryas. The classification of Dryas within the Rosaceae has been unclear...
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: TandoniaTandoniaTandonia is a genus of air-breathing, keeled, land slugs. These are shell-less terrestrial gastropod mollusks in the family Milacidae.- Distribution :Distribution of genus Tandonia include Europe to north Africa and Asia Minor...
), 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 GastropodaGastropodaThe Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomic class within the phylum Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to quite large...
, but the name is also (rarely) used for a group in Arachnida. - Reticulata is used as an order in ForaminiferaForaminiferaThe Foraminifera , or forams for short, are a large group of amoeboid protists which are among the commonest plankton species. They have reticulating pseudopods, fine strands of cytoplasm that branch and merge to form a dynamic net...
, 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 (Foraminifera) and BuliminusBuliminusBuliminus, is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Enidae.-References:*...
(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 to be asked for a solution (Opinion 2018). - Claria (Rotifera) and ClariasClariasClarias is a genus of catfishes 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 of water....
(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 needed to be amended to Clariaidae (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 to provide the objective standard of reference by which the application of the name is determined.This means that any named taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
would have a name-bearing type
Name-bearing type
Under the International Code of Zoological Nomenclature , the name-bearing type is the biological type that determines the application of a name. Each taxon regulated by the Code at least potentially has a name-bearing type. The name-bearing type can be either a type genus , type species , or 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
Type genus
In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
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 SpheniscusSpheniscusThe banded penguins are the penguins of the Spheniscus genus. There are four living species of penguins known as banded penguins, and all have similar coloration. They are sometimes also known as "Jack-ass penguins" due to their loud locator calls sounding similar to a donkey braying...
Brisson, 1760.
The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
for a genus-group name is more complicated and follows exactly defined provisions in Art. 67-69.
Type species are very important, and there is no general zoological database that 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 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 will always be 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:
- GalbaGalbaGalba , was Roman Emperor for seven months from 68 to 69. Galba was the governor of Hispania Tarraconensis, and made a bid for the throne during the rebellion of Julius Vindex...
Schrank, 1803 (Gastropoda) was established with one species included, Galba pusilla 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 Müller, 1774 was fixed as type species under the plenary power(s) (currently Galba truncatulaGalba truncatulaGalba truncatula is a species of air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Lymnaeidae, the pond snails.Until recently, this species was commonly known as Lymnaea truncatula.-Description:...
).
- Designation under Art. 70.3 (misidentified type species) (1 %)
- Examples:
- Bollingeria Forcart, 1940 (Gastropoda) was established with its type species Chondrus pupoides 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.
- HelisomaHelisomaHelisoma is a genus of freshwater air-breathing snail, a pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails.-Species:Species within the genus Helisoma include:...
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 Say, 1821 and not Planorbis bicarinatus Say, 1819 was meant. But since the incorrect type species Planorbis bicarinatus 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 TheodoxusTheodoxusTheodoxus is a genus of small freshwater and brackish water neritid snail with an operculum.- Distribution :Distribution of the genus Theodoxus include Europe and northern Africa to southern Iran.- Description :...
(Gastropoda) and designated Theodoxus lutetianus Montfort 1810 as type species (currently Theodoxus fluviatilisTheodoxus fluviatilisTheodoxus fluviatilis, common name the river nerite, is a small species of freshwater and brackish water snail with a gill and an operculum. It is an aquatic gastropod mollusk in the family Neritidae, the nerites....
). - Vest 1867 established the subgenus Clausilia (Isabellaria) (Gastropoda) and designated Clausilia isabellina Pfeiffer, 1842 as type species (currently Isabellaria isabellina).
- Riedel 1987 established the genus Turcozonites (Gastropoda) and designated Zonites wandae Riedel, 1982 as type species (currently Turcozonites wandae).
- Monotypy (28 %)
- Examples:
- AnodontaAnodontaAnodonta is a genus of medium-sized to large freshwater mussels, aquatic bivalve molluscs in the family Unionidae.-Species:Species in this genus include:* Duck mussel, Anodonta anatina Linné, 1758* Anodonta beringiana Middendorff, 1851...
Lamarck, 1799 (Bivalvia) was originally established with one included nominal species, Mytilus cygneus Linnæus, 1758. This is the type species fixed by monotypy (currently Anodonta cygnea). - Microcondylaea Vest 1866 (Bivalvia) was originally established with two included nominal species, Unio bonellii Férussac, 1827 and with doubts Anodonta lata Rafinesque, 1820. Doubtfully included species do not count, type species is Unio bonellii fixed by monotypy (currently Microcondylaea bonellii).
- Absolute tautonymy (2 %)
- Examples:
- Kobelt 1871 established the gastropod genus-group name CandidulaCandidulaCandidula is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Hygromiidae, the hairy snails and their allies.-Species:Species within the genus Candidula include:* Candidula arganica...
and included 23 species. Among these was Glischrus candidula Studer 1820. Glischrus candidula is type species fixed by absolute tautonymy (currently Candidula unifasciataCandidula unifasciataCandidula unifasciata is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Hygromiidae, the hairy snails and their allies.- Distribution :This species occurs in European countries and islands including:...
). - Draparnaud 1801 established the gastropd genus SuccineaSuccineaSuccinea, common name amber snails, is a genus of small, air-breathing, land snails, terrestrial pulmonate gastropod molluscs in the family Succineidae.They usually live in damp habitats such as marshes.-Species:...
and included two species, Succinea amphibia Draparnaud 1801 and Succinea oblonga Draparnaud 1801. Among the synonyms of S. amphibia, Draparnaud listed a name Helix succinea Müller 1774. Synonyms do count here, so Helix succinea is type species by absolute tautonymy (currently Succinea putrisSuccinea putrisSuccinea putris is a species of small, air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Succineidae, the amber snails.-Distribution:Distribution: European-Siberian region.* Czech Republic - least concern * Germany...
). - Kobelt 1904 established the gastropod subgenus Iberus (Balearica) and included 10 species. Among these was Helix balearica Rossmässler 1838, which Kobelt cited as Iberus (Balearica) balearicus. The ending -us is irrelevant here, Helix balearica is type species by absolute tautonymy (currently Iberellus balearicus or Iberellus hispanicus).
- Euxinolauria 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 4 species, among which was Pupa caucasica Pfeiffer, 1857. This is the type species for Caucasica Caziot & Margier, 1909 fixed by absolute tautonymy, and also for Euxinolauria (currently Euxinolauria caucasica).
- The following examples do not represent absolute tautonymy: Scomber scombrus Linnæus, 1758 (Actinopterygii), Babyrousa babyrussa (Linnæus, 1758) (Mammalia), Suricata suricatta (Schreber, 1776) (Mammalia), Merlangius merlangusMerlangius merlangusMerlangius merlangus, commonly known as whiting is an important food fish in the eastern North Atlantic, northern Mediterranean, western Baltic, and Black Sea...
(Linnæus, 1758) (Actinopterygii), Isabellaria isabellina (Pfeiffer, 1842) (Gastropoda), Rupestrella rupestris (Philippi, 1836) (Gastropoda).
- Linnean tautonymy (0.3 %)
- Example:
- Linnæus 1758 established CastorCastorCastor derives from the , meaning "beaver", or "he who excels". It originally referred to Castor, one of the Dioscuri/Gemini twins of Graeco-Roman mythology.Castor or CASTOR may also refer to:-Science and technology:...
(Mammalia) and included two species, Castor fiber and Castor moschatus. 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 Linnæus 1758 is type species fixed by Linnean tautonymy (currently Castor fiber).- Subsequent methods of type fixation:
- Subsequent monotypy (2 %)
- Examples:
- ValvataValvataValvata is a genus of very small freshwater snails with an operculum, aquatic gastropod mollusks in the family Valvatidae, the valve snails.-Species:The type species for this genus is Valvata cristata O.F. Müller, 1774....
Müller, 1773 (Gastropoda) was established with a short description and without species. Müller 1774 included one species Valvata cristataValvata cristataValvata cristata is a species of minute freshwater snail with an operculum, an aquatic gastropod mollusk or micromollusk in the family Valvatidae, the valve snails.-Shell description:...
Müller 1774. Valvata cristataValvata cristataValvata cristata is a species of minute freshwater snail with an operculum, an aquatic gastropod mollusk or micromollusk in the family Valvatidae, the valve snails.-Shell description:...
is type species by subsequent monotypy (currently Valvata cristataValvata cristataValvata cristata is a species of minute freshwater snail with an operculum, an aquatic gastropod mollusk or micromollusk in the family Valvatidae, the valve snails.-Shell description:...
). - OmphiscolaOmphiscolaOmphiscola is a genus of small to medium-sized, air-breathing, freshwater snails, aquatic pulmonate gastropod mollusks in the family Lymnaeidae.-Species:Species within the genus include:* Omphiscola glabra - type species...
Rafinesque, 1819 (Gastropoda) was established without species included. Beck 1837 [1838] included one species Buccinum glabrum Müller, 1774. Buccinum glabrum is type species by subsequent monotypy (currently Omphiscola glabraOmphiscola glabraOmphiscola glabra is a species of small to medium-size, air-breathing, freshwater snail, an aquatic pulmonate gastropod mollusk in the family Lymnaeidae.-Distribution:This European snail can be found from southern Scandinavia to southern Spain....
).
- 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 and Clupea fincta. Type species is Clupea alosa Linnæus 1758 by subsequent absolute tautonymy (currently Alosa alosa).
- RupicapraRupicapraRupicapra is a genus of the family Bovidae , which contains two species:*Chamois *Pyrenean Chamois .-External links and references:...
Garsault, 1764 (Mammalia) was established without included species. As first author, Blainville, 1816 included 3 species Capra rupicapra Linnæus, 1758, Capra pudu and Capra americana. Type species is Capra rupicapra by subsequent absolute tautonymy (currently Rupicapra rupicapra).
- Subsequent Linnean tautonymy (only theoretical, there might be no case)
- Subsequent designation (32 %)
- Examples:
- AplexaAplexaAplexa is a genus of small, left-handed or sinistral, air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the family Physidae.-Shell description:...
Fleming, 1820 (Gastropoda) was established with two species, Bulla hypnorum Linnæus, 1758 and Bulla rivalis Turton, 1807. Herrmannsen 1846 fixed Bulla hypnorum as type by subsequent designation (currently Aplexa hypnorumAplexa hypnorumAplexa hypnorum, 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....
). - PseudanodontaPseudanodontaPseudanodonta is a genus of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels.-Species:Species within this genus include:* Pseudanodonta complanata* Pseudanodonta middendorffi...
Bourguignat 1877 (Bivalvia) was established with 7 species, Anodonta complanata Rossmässler 1835 and 6 others. Westerlund 1902 validly designated Anodonta complanata as type species (currently Pseudanodonta complanata).
- Designation by ICZN under the plenary powers (3 %)
A species-group name can have a name-bearing type specimen, but this is no must. 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 which will be binding for the users of that name. Fixing such a name-bearing type should only be done if this is taxonomically necessary (Art. 74.7.3, 75.2, 75.3).
Examples:
- Aptenodytes patagonica Miller, 1778 is either based on a type specimen, perhaps deposited in the Natural History MuseumNatural History MuseumThe Natural History Museum is one of three large museums on Exhibition Road, South Kensington, London, England . Its main frontage is on Cromwell Road...
London or somewhere else, or its type is lost. This is currently irrelevant because the usage of the name (as Aptenodytes patagonicus) for the king penguinKing PenguinThe King Penguin is the second largest species of penguin at about , second only to the Emperor Penguin. There are two subspecies—A. p. patagonicus and A. p...
is unambiguously accepted. - The name-bearing type for Homo sapiens Linnæus, 1758 is deposited in Uppsala (the bones of Carl von Linné). This is a lectotypeLectotypeIn botanical nomenclature and zoological nomenclature, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype...
designated by Stearn 1959, correctly but unnecessarily because the usage of the name was unambiguous at that time and still is.
Links to the separate articles (these are redundant and can eventually be removed):
- Principle of CoordinationPrinciple of CoordinationIn zoology, the Principle of Coordination is one of the guiding principles of the International Code of Zoological Nomenclature.It states that the act of publishing a new zoological name thereby automatically and simultaneously establishes all the corresponding names in the relevant other ranks,...
- Principle of the First ReviserPrinciple of the First ReviserIn zoology, the Principle of the First Reviser is one of the guiding principles of the International Code of Zoological Nomenclature.It supplements the Principle of Priority, which states that the first published name takes precedence...
- Principle of HomonymyPrinciple of HomonymyIn zoology, the Principle of Homonymy is one of the guiding principles of the International Code of Zoological Nomenclature.It states that any one name, in one particular spelling, may be used only once . This will be the first-published name; any later name with the same spelling is barred from...
- Principle of PriorityPrinciple of Prioritythumb|270px|Boa manditraIn zoology, the scientific study of animals, the Principle of Priority is one of the guiding principles of the International Code of Zoological Nomenclature, defined by Article 23....
- Principle of TypificationPrinciple of TypificationIn zoology, the Principle of Typification is one of the guiding principles of the International Code of Zoological Nomenclature.It states that any named taxon, in the family group, genus group or species group, has a name-bearing type which allows the application of the name of the taxon to be...
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 group, the genus group and the species group are fully regulated by the provisions in the Code. There is no limitation to the number of ranks allowed in the family group. In the genus group there are only two ranks: the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
and the subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
. In the species group there are only two ranks: the species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
and the subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
.
Gender agreement
In the species group gender agreement applies. The name of a species, in two parts, a binomenBinomen
In zoological nomenclature, a binomen , is the two-part name of a species. The term was introduced in 1953, abolishing the previously used "binomial name" . A binomen consists of a generic name and a specific epithet...
, say, Loxodonta africana, and of a subspecies, in three parts, a trinomen
Trinomen
In zoological nomenclature, a trinomen , or trinominal name, refers to the name of a subspecies.A trinomen is a name consisting of three names: generic name, specific name and subspecific name. The first two parts alone form the binomen or species name. All three names are typeset in italics, and...
, say Canis lupus albus, originally is a Latin phrase, and must be grammatically correct Latin. If the second part, the specific name (or the third part, the subspecific name
Subspecific name
In zoological nomenclature, a subspecific name is the third part of a trinomen. In zoology there is only one rank below that of species, namely "subspecies"....
) is adjectival
Adjective
In grammar, an adjective is a 'describing' word; the main syntactic role of which is to qualify a noun or noun phrase, giving more information about the object signified....
in nature, its ending must agree in gender with the name of the genus. If it is a noun, or an arbitrary combinations of letters, this does not apply.
- For instance, the generic name EquusEquus (genus)Equus is a genus of animals in the family Equidae that includes horses, donkeys, and zebras. Within Equidae, Equus is the only extant genus. Like Equidae more broadly, Equus has numerous extinct species known only from fossils. This article deals primarily with the extant species.The term equine...
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 specific name zebra is a noun, it may not be "corrected" to "Equus zebrus".
- In Equus quagga burchellii the subspecific name burchellii is a noun in the genitive ("of the esteemed Burchell").
If a species is moved, therefore, the spelling of an ending may need to be changed. If Gryllus migratorius is moved to the genus Locusta
Locusta
Locusta was a Roman serial killer during the 1st century AD.Locusta was born in the Roman province of Gaul. In AD 54, she may have been hired by Agrippina the Younger to kill the Emperor Claudius, possibly with a poisoned dish of mushrooms. In 55, she was convicted of poisoning another victim...
, it becomes Locusta migratoria. Confusion over proper Latin grammar have led to many incorrectly formed names appearing in print. An improper 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).
Accordingly, many laymen and some scientists object to continued adherence to this rule, especially those who work with butterflies and moths
Moths
Moths may refer to:* Gustav Moths , German rower* The Moths!, an English indie rock band* MOTHS, members of the Memorable Order of Tin Hats...
. This has historical reasons. In 1758, Linnæus placed all butterflies in the genus Papilio
Papilio
Papilio is a genus in the swallowtail butterfly family, Papilionidae. The word papilio is Latin for butterfly.The genus includes a number of well-known North American species such as the Western Tiger Swallowtail...
, which after a few decades contained thousands of species. From the beginning on the gender of Papilio was unclear, undecided and disputed. Some authors regarded it as masculine, others as feminine. Linnæus knew this problem and avoided any statement. All his 250 specific names in the genus Papilio were either nouns, unchangeable adjectives or adjectives ending in -is. He strictly did not use a single adjective ending in -us, -a, -um. P. Brown, Cramer
Pieter Cramer
Pieter Cramer , was a wealthy Dutch merchant in linen and Spanish wool, and an entomologist. Cramer was the director of the Zealand Society, a scientific society located in Flushing and a member of Concordia et Libertate, based in Amsterdam...
, Fabricius
Johan Christian Fabricius
Johan Christian Fabricius was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others...
, Fueßlin
Johann Kaspar Füssli
Johann Kaspar Füssli, also written Johann Caspar Fuesslins, was a Swiss painter, entomologist and publisher....
, Goeze
Johann August Ephraim Goeze
Johann August Ephraim Goeze was a German zoologist from Aschersleben.He was the son of Johann Heinrich and Catherine Margarete . He studied theology at University of Halle. He married Leopoldine Maria Keller in 1770, by whom he had four children. In 1751, he became a pastor at Aschersleben in...
, Poda
Nikolaus Poda von Neuhaus
Nikolaus Poda von Neuhaus was an Austrian entomologist born in Vienna.Von Neuhaus was the author of Insecta Musei Graecensis , the first purely entomological work to follow the binomial nomenclature of Carolus Linnaeus.-External links:**...
and Schrank regarded Papilio as masculine, Ménétriés
Édouard Ménétries
Édouard Ménétries was a French entomologist, zoologist, and herpetologist.Ménétries was born in Paris, and became a student of Georges Cuvier and Pierre André Latreille. On their recommendation he was chosen as the zoologist on a Russian expedition to Brazil in 1822, led by Baron von Langsdorff...
, Pontoppidan
Erik Pontoppidan
Erik Pontoppidan was a Danish author, bishop, historian and antiquary, born in Aarhus August 24, 1698; died in Copenhagen December 20, 1764. He was educated in Fredericia , after which he was a private tutor in Norway, and then studied in Holland, and in London and Oxford, England...
and most modern authors as feminine. In ICZN Opinion 278 from 1954 it was regarded as masculine. In many cases lepidopterists would not change the ending of a name as used by the author who established a name. So we find for example Papilio fuscus
Papilio fuscus
The Canopus Swallowtail is a butterfly of the Papilionidae family, that is found on Timor, Northern Australia and New Guinea.The wingspan is about 80 mm.The larvae feed on Rutaceae species.-External links:* *...
or Papilio macilentus
Papilio macilentus
Papilio macilentus is a Papilionidae butterfly found in Japan, China and Korea. It is found in the valleys or the margins of the forest. This species has the longest tail in the family Papilionidae. The spring type is found from April to June, and the summer type from July to August. The larvae...
, but also Papilio osmana
Papilio osmana
Papilio osmana is a species of butterfly in the Papilionidae family. It is endemic to the Philippines.-Source:* Gimenez Dixon, M. 1996. . Downloaded on 31 July 2007....
and Papilio paradoxa. Only in few cases both versions are found in the web (an example is Papilio multicaudatus and Papilio multicaudata). This works also with other butterfly genera of which the gender is undisputed. Graphium
Graphium
Graphium is a genus of mostly tropical swallowtail butterflies commonly known as swordtails, kite swallowtails, or ladies. Native to Eurasia, Africa, and Oceania, the genus is represented by over 100 species. Their coloration is as variable as the habitats they frequent; from rainforest to savannah...
is clearly neuter, but only the incorrect versions Graphium angolanus
Graphium angolanus
The Angola White Lady is a species of butterfly in the Papilionidae family, found in Subsaharan Africa.The wingspan is 65–70 mm in males and 70–75 mm in females...
and Graphium mandarinus are used, while Graphium sandawanum can only be found in the correct declination. Likewise pairs are more frequently found in genera of which the gender is not obvious: Delias castaneus and Delias gigantea, Belenois albumaculatus and Belenois rubrosignata, Mylothris arabicus and Mylothris ruandana. Even in moths such pairs can be found: Xylophanes obscurus
Xylophanes obscurus
Xylophanes obscurus is a moth of the Sphingidae family. It is known from Peru and Brazil.It is similar to Xylophanes cosmius but the forewing upperside is darker, more uniform and sombre brown. Furthermore, the dark patch distal to discal spot is larger and trapezoidal. The conspicuous postmedian...
and Xylophanes turbata
Xylophanes turbata
Xylophanes turbata is a moth of the Sphingidae family. It is known from Mexico to Nicaragua and Costa Rica. An occasional stray may be found up to southern Arizona....
, Manduca boliviana
Manduca boliviana
Manduca boliviana is a moth of the Sphingidae family. It is known from Bolivia.The length of the forewings is about 44 mm. It is similar to Manduca scutata and Manduca brasiliensis, but smaller, much lighter coloured and the forewings are shorter and more rounded than the latter...
and Manduca caribbeus
Manduca caribbeus
Manduca caribbeus is a moth of the Sphingidae family. It is known from Haiti and the Dominican Republic.The wingspan is 80-85 mm. Adults have been recorded from May to June....
, Sphinx caligineus
Sphinx caligineus
Sphinx caligineus is a moth of the Sphingidae family. It is known from Japan, north-eastern, eastern, central and southern China, South Korea, northern Thailand and southern Vietnam.The wingspan is 55-76 mm....
and Sphinx formosana
Sphinx formosana
Sphinx formosana is a moth of the Sphingidae family. It is known from the northern central mountains of Taiwan....
, Macroglossum albolineata
Macroglossum albolineata
Macroglossum albolineata is a moth of the Sphingidae family. It is known from Papua New Guinea....
and Macroglossum vicinum
Macroglossum vicinum
Macroglossum vicinum is a moth of the Sphingidae family. It is known from southern India, southern China and Thailand.The wingspan is 40-48 mm. It is a forest species which is on wing during the rainy season....
. It may also occur that a lepidopteran subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
can have a different gender than the name of the species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, as for example in Papilio multicaudata pusillus Austin & Emmel, 1998, or Papilio torquatus flavida Oberthür, 1879.
Commission
The rules in the Code are to be followed by 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 his or her field, but only by the International Commission on Zoological NomenclatureInternational Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 28 members from 20 countries, mainly practicing zoological taxonomists...
, acting on behalf of all zoologists. The Commission takes such action in response to proposals submitted to it.
- Carolus LinnaeusCarolus LinnaeusCarl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...
named the Domestic Cat Felis catus in 1758; Johann Christian Daniel von SchreberJohann Christian Daniel von SchreberJohann Christian Daniel von Schreber , often styled I.C.D. von Schreber, was a German naturalist.-Career:He was elected Professor of Materia medica at the University of Erlangen in 1769....
named the WildcatWildcatWildcat is a small felid native to Europe, the western part of Asia, and Africa.-Animals:Wildcat may also refer to members of the genus Lynx:...
Felis silvestris in 1775. For taxonomists who consider these two kinds of cat to be a single species the Principle of PriorityPrinciple of Prioritythumb|270px|Boa manditraIn zoology, the scientific study of animals, the Principle of Priority is one of the guiding principles of the International Code of Zoological Nomenclature, defined by Article 23....
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 2027Opinion 2027Opinion 2027 is a ruling of the International Commission on Zoological Nomenclature concerning the conservation of 17 species names of wild animals with domestic derivatives...
) 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 to be 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.
See also
- BinomenBinomenIn zoological nomenclature, a binomen , is the two-part name of a species. The term was introduced in 1953, abolishing the previously used "binomial name" . A binomen consists of a generic name and a specific epithet...
- TrinomenTrinomenIn zoological nomenclature, a trinomen , or trinominal name, refers to the name of a subspecies.A trinomen is a name consisting of three names: generic name, specific name and subspecific name. The first two parts alone form the binomen or species name. All three names are typeset in italics, and...
- Rank (zoology)
- Homonym (biology)
- Synonym (taxonomy)Synonym (taxonomy)In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
- Nomen oblitumNomen oblitumA nomen oblitum is a technical term, used in zoological nomenclature, for a particular kind of disused scientific name....
- Nomen dubiumNomen dubiumIn zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
- Nomen nudumNomen nudumThe phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
- International Code of Botanical Nomenclature