International Code of Zoological Nomenclature

In regulating the names of animals it holds by six central principles, which were first set out (as principles) in the third edition of the code (1985): Principle of binominal nomenclature This is the principle that the scientific name of a species, and not of a taxon at any other rank, is a combination of two names; the use of a trinomen for the name of a subspecies and of uninominal names for taxa above the species group is in accord with this principle. This means that in the system of nomenclature for animals, the name of a species is composed of a combination of a generic name and a specific name; together they make a "binomen". No other rank can have a name composed of two names. Examples: :Species Giraffa camelopardalis • Subspecies have a name composed of three names, a "trinomen": generic name, specific 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. There are over 2 million junior synonyms recorded in zoology, primarily at the species level. 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. 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, citing both names and selecting 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. Examples: :The genus Tandonia was established in animals (Gastropoda), in plants (Euphorbiaceae), and in Fungi (Ascomycetes). :Prominent plant/animal pairings: Ammophila (Poaceae and Hymenoptera), Arenaria (Caryophyllaceae and Aves), Betula (Betulaceae and Hymenoptera), Chloris (Cactaceae and Aves), Dryas (Rosaceae and Lepidoptera), Dugesia (Asteraceae and Platyhelminthes), Erica (Ericaceae and Araneae), Hystrix (Poaceae and Mammalia), Iris (Iridaceae and Orthoptera), Liparis (Orchidaceae and Actinopterygii), Phalaenopsis (Orchidaceae and Aves), Pinus (Pinaceae and Mollusca), Prunella (Lamiaceae and Aves), Ricinus (Euphorbiaceae and Psocodea), Taxus (Taxaceae and Mammalia), Typha (Typhaceae and Porifera), Ulva (Ulvophyceae and Lepidoptera), Viola (Violaceae and Lepidoptera). 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 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 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) (now Galba truncatula). ::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. :::Helisoma 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 Theodoxus (Gastropoda) and designated Theodoxus lutetianus Montfort 1810 as type species (now Theodoxus fluviatilis). :::Vest 1867 established the subgenus Clausilia (Isabellaria) (Gastropoda) and designated Clausilia isabellina Pfeiffer, 1842 as type species (now Isabellaria isabellina). :::Riedel 1987 established the genus Turcozonites (Gastropoda) and designated Zonites wandae Riedel, 1982 as type species (now Turcozonites wandae). ::Monotypy (28%) :::Examples: :::Anodonta Lamarck, 1799 (Bivalvia) was originally established with one included nominal species, Mytilus cygneus Linnaeus, 1758. This is the type species fixed by monotypy (now 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 (now Microcondylaea bonellii). ::Absolute tautonymy (2%) :::Examples: :::Kobelt 1871 established the gastropod genus-group name Candidula and included 23 species. Among these was Glischrus candidula Studer 1820. Glischrus candidula is type species fixed by absolute tautonymy (now Candidula unifasciata). :::Draparnaud 1801 established the gastropod genus Succinea 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 (now Succinea putris). :::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 four 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 (now Euxinolauria caucasica). :::The following examples do not represent absolute tautonymy: Scomber scombrus Linnaeus, 1758 (Actinopterygii), Babyrousa babyrussa (Linnaeus, 1758) (Mammalia), Suricata suricatta (Schreber, 1776) (Mammalia), Merlangius merlangus (Linnaeus, 1758) (Actinopterygii), Isabellaria isabellina (Pfeiffer, 1842) (Gastropoda), Rupestrella rupestris (Philippi, 1836) (Gastropoda). ::Linnean tautonymy (0.3%) :::Example: :::Linnaeus 1758 established Castor (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 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 Müller 1774. Valvata cristata is type species by subsequent monotypy (now Valvata cristata). :::Omphiscola 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 (now Omphiscola glabra). ::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 Linnaeus 1758 by subsequent absolute tautonymy (now Alosa alosa). :::Rupicapra Garsault, 1764 (Mammalia) was established without included species. As first author, Blainville, 1816 included three species Capra rupicapra Linnaeus, 1758, Capra pudu, and Capra americana. Type species is Capra rupicapra by subsequent absolute tautonymy (now Rupicapra rupicapra). ::Subsequent Linnean tautonymy (only theoretical, there might be no case) ::Subsequent designation (32%) :::Examples: :::Aplexa Fleming, 1820 (Gastropoda) was established with two species, Bulla hypnorum Linnaeus, 1758 and Bulla rivalis Turton, 1807. Herrmannsen 1846 fixed Bulla hypnorum as type by subsequent designation (now Aplexa hypnorum). :::Pseudanodonta Bourguignat 1877 (Bivalvia) was established with seven species, Anodonta complanata Rossmässler 1835, and six others. Westerlund 1902 validly designated Anodonta complanata 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 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) 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. The species group has only two ranks: species and subspecies. Gender agreement In the species group gender agreement applies. If the name of a species, in two parts, a binomen, say, Loxodonta africana, or of a subspecies, in three parts, a trinomen, for example, Canis lupus albus, is in the form of a Latin phrase, it 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 combination of letters, this does not apply. • For instance, the generic name Equus is masculine; in the name "Equus africanus", the specific name africanus is an adjective and its ending follows the gender of the generic name. • 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 case ("of Burchell"). If a species is moved, 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 Code 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 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 International Commission on Zoological Nomenclature. The ICZN Commission takes its power from a general biological congress (IUBS, International Union of Biological Sciences). The editorial committee for the fourth edition was composed of seven persons. Such new editions of the ICZN Code are not democratically approved by the 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 International Commission on Zoological Nomenclature, acting on behalf of all zoologists. The Commission takes such action in response to proposals submitted to it. == Electronic publications ==

The latest amendments (specifically A-2012) 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 requires 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. Local changes, such as the changes proposed by the Turkish government, are not recognised by the ICZN. ==Citation==

• Strickland, H.E. [et 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. BHL. [Also 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. BHL. • ICZN. 1964. International Code of Zoological Nomenclature. Second edition. The International Trust for Zoological Nomenclature, London, UK. BHL. • ICZN. 1985. International Code of Zoological Nomenclature. Third edition. The International Trust for Zoological Nomenclature, London, UK. BHL. • ICZN. 1999. International Code of Zoological Nomenclature. Fourth edition. The International Trust for Zoological Nomenclature, London, UK. BHL. The Code Online (ICZN). ==See also==