International Code of Zoological Nomenclature

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Not to be confused with International Commission on Zoological Nomenclature. International Code of Zoological Nomenclature_sentence_0

"Animal naming" redirects here. International Code of Zoological Nomenclature_sentence_1

For all other animal names, see List of animal names. International Code of Zoological Nomenclature_sentence_2

The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. International Code of Zoological Nomenclature_sentence_3

It is also informally known as the ICZN Code, for its publisher, the International Commission on Zoological Nomenclature (which shares the acronym "ICZN"). International Code of Zoological Nomenclature_sentence_4

The rules principally regulate: International Code of Zoological Nomenclature_sentence_5

International Code of Zoological Nomenclature_unordered_list_0

  • How names are correctly established in the frame of binominal nomenclatureInternational Code of Zoological Nomenclature_item_0_0
  • Which name must be used in case of name conflictsInternational Code of Zoological Nomenclature_item_0_1
  • How scientific literature must cite namesInternational Code of Zoological Nomenclature_item_0_2

Zoological nomenclature is independent of other systems of nomenclature, for example botanical nomenclature. International Code of Zoological Nomenclature_sentence_6

This implies that animals can have the same generic names as plants. International Code of Zoological Nomenclature_sentence_7

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. International Code of Zoological Nomenclature_sentence_8

The code is meant to guide only the nomenclature of animals, while leaving zoologists freedom in classifying new taxa. International Code of Zoological Nomenclature_sentence_9

In other words, whether a species itself is or is not a recognized entity is a subjective decision, but what name should be applied to it is not. International Code of Zoological Nomenclature_sentence_10

The code applies only to the latter. International Code of Zoological Nomenclature_sentence_11

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). International Code of Zoological Nomenclature_sentence_12

The rules in the code determine what names are valid for any taxon in the family group, genus group, and species group. International Code of Zoological Nomenclature_sentence_13

It has additional (but more limited) provisions on names in higher ranks. International Code of Zoological Nomenclature_sentence_14

The code recognizes no case law. International Code of Zoological Nomenclature_sentence_15

Any dispute is decided first by applying the code directly, and not by reference to precedent. International Code of Zoological Nomenclature_sentence_16

The code is also retroactive or retrospective, which means that previous editions of the code, or previous other rules and conventions have no force any more today, and the nomenclatural acts published 'back in the old times' must be evaluated only under the present edition of the code. International Code of Zoological Nomenclature_sentence_17

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. International Code of Zoological Nomenclature_sentence_18

Principles International Code of Zoological Nomenclature_section_0

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): International Code of Zoological Nomenclature_sentence_19

Principle of binominal nomenclature International Code of Zoological Nomenclature_section_1

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. International Code of Zoological Nomenclature_sentence_20

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". International Code of Zoological Nomenclature_sentence_21

No other rank can have a name composed of two names. International Code of Zoological Nomenclature_sentence_22

Examples: International Code of Zoological Nomenclature_sentence_23

International Code of Zoological Nomenclature_description_list_1

International Code of Zoological Nomenclature_unordered_list_2

International Code of Zoological Nomenclature_description_list_3

International Code of Zoological Nomenclature_unordered_list_4

  • Taxa at a rank above species have a name composed of one name, a "uninominal name".International Code of Zoological Nomenclature_item_4_6

International Code of Zoological Nomenclature_description_list_5

  • Genus Giraffa, family GiraffidaeInternational Code of Zoological Nomenclature_item_5_7

In botanical nomenclature, the equivalent for "binominal nomenclature" is "binary nomenclature" (or sometimes "binomial nomenclature"). International Code of Zoological Nomenclature_sentence_24

Principle of priority International Code of Zoological Nomenclature_section_2

Main article: Principle of Priority International Code of Zoological Nomenclature_sentence_25

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. International Code of Zoological Nomenclature_sentence_26

It is the most important principle—the fundamental guiding precept that preserves zoological nomenclature stability. International Code of Zoological Nomenclature_sentence_27

It was first formulated in 1842 by a committee appointed by the British Association to consider the rules of zoological nomenclature. International Code of Zoological Nomenclature_sentence_28

Hugh Edwin Strickland wrote the committee's report. International Code of Zoological Nomenclature_sentence_29

Example: International Code of Zoological Nomenclature_sentence_30

International Code of Zoological Nomenclature_description_list_6

  • Nunneley 1837 established Limax maculatus (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 must be used for the species.International Code of Zoological Nomenclature_item_6_8

There are approximately 2-3 million cases of this kind for which this principle is applied in zoology. International Code of Zoological Nomenclature_sentence_31

Principle of coordination International Code of Zoological Nomenclature_section_3

Main article: Principle of Coordination International Code of Zoological Nomenclature_sentence_32

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. International Code of Zoological Nomenclature_sentence_33

In other words, publishing a new zoological name automatically and simultaneously establishes all corresponding names in the relevant other ranks with the same type. International Code of Zoological Nomenclature_sentence_34

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. International Code of Zoological Nomenclature_sentence_35

The same applies to the name of a subspecies; this establishes the corresponding species name. International Code of Zoological Nomenclature_sentence_36

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. International Code of Zoological Nomenclature_sentence_37

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). International Code of Zoological Nomenclature_sentence_38

Author citations for such names (for example a subgenus) are the same as for the name actually published (for example a genus). International Code of Zoological Nomenclature_sentence_39

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. International Code of Zoological Nomenclature_sentence_40

Principle of the first reviser International Code of Zoological Nomenclature_section_4

This is the principle that in cases of conflicts between simultaneously published divergent acts, the first subsequent author can decide which has precedence. International Code of Zoological Nomenclature_sentence_41

It supplements the principle of priority, which states that the first published name takes precedence. International Code of Zoological Nomenclature_sentence_42

The principle of the first reviser deals with situations that cannot be resolved by priority. International Code of Zoological Nomenclature_sentence_43

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. International Code of Zoological Nomenclature_sentence_44

In such cases, the first subsequent author who deals with the matter and chooses and publishes the decision in the required manner is the first reviser, and is to be followed. International Code of Zoological Nomenclature_sentence_45

Example: International Code of Zoological Nomenclature_sentence_46

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. International Code of Zoological Nomenclature_sentence_47

The two names are subjective synonyms. International Code of Zoological Nomenclature_sentence_48

Lönnberg 1931 acted as first reviser, cited both names and selected Strix scandiaca to have precedence. International Code of Zoological Nomenclature_sentence_49

Principle of homonymy International Code of Zoological Nomenclature_section_5

Main article: Principle of Homonymy International Code of Zoological Nomenclature_sentence_50

This is the principle that the name of each taxon must be unique. International Code of Zoological Nomenclature_sentence_51

Consequently, a name that is a junior homonym of another name must not be used as a valid name. International Code of Zoological Nomenclature_sentence_52

It means that any one animal name, in one particular spelling, may be used only once (within its group). International Code of Zoological Nomenclature_sentence_53

This is usually the first-published name; any later name with the same spelling (a homonym) is barred from being used. International Code of Zoological Nomenclature_sentence_54

The principles of priority and first reviser apply here. International Code of Zoological Nomenclature_sentence_55

For family-group names the termination (which is rank-bound) is not taken into account. International Code of Zoological Nomenclature_sentence_56

Genera are homonyms only if exactly the same — a one-letter difference is enough to distinguish them. International Code of Zoological Nomenclature_sentence_57

Examples: International Code of Zoological Nomenclature_sentence_58

International Code of Zoological Nomenclature_description_list_7

  • 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)International Code of Zoological Nomenclature_item_7_9
  • Argus Scopoli, 1763 (Lepidoptera: Lycaenidae: Polyommatinae)International Code of Zoological Nomenclature_item_7_10
  • Argus Scopoli, 1777 (Lepidoptera: Nymphalidae: Satyrinae)International Code of Zoological Nomenclature_item_7_11
  • Argus Poli, 1791 (Bivalvia)International Code of Zoological Nomenclature_item_7_12
  • Argus Temminck, 1807 (Aves)International Code of Zoological Nomenclature_item_7_13
  • Argus Lamarck, 1817 (Lepidoptera: Hesperiidae)International Code of Zoological Nomenclature_item_7_14
  • Argus Walckenaer, 1836 (Araneae)International Code of Zoological Nomenclature_item_7_15
  • Argus Gerhard, 1850 (Lepidoptera: Lycaenidae: Theclinae)International Code of Zoological Nomenclature_item_7_16
  • Homonyms of Argus are not:International Code of Zoological Nomenclature_item_7_17
  • Argua Walker, 1863 (Lepidoptera), Argusa Kelham, 1888 (Aves), Argusina Hebard, 1927 (Dermaptera), Arcus Hong, 1983 (Diptera), Argas Latreille, 1795 (Araneae), Argulus Müller, 1785 (Crustacea).International Code of Zoological Nomenclature_item_7_18

International Code of Zoological Nomenclature_description_list_8

  • Not homonyms of each others: Isomya Cutler & Cutler, 1985 (Sipunculida), Isomyia Walker, 1859 (Diptera).International Code of Zoological Nomenclature_item_8_19
  • Not homonyms of each others: Adelomya Mulsant & Verreaux, 1866 (Aves), Adelomyia Bonaparte, 1854 (Aves), Adelomys Gervais, 1853 (Mammalia), Adolomys Shevyreva, 1989 (Mammalia), Adulomya Kuroda, 1931 (Bivalvia).International Code of Zoological Nomenclature_item_8_20

In species, there is a difference between primary and secondary homonyms. International Code of Zoological Nomenclature_sentence_59

There can also be double homonyms (same genus and species). International Code of Zoological Nomenclature_sentence_60

A slight difference in spelling is tolerated if Article 58 applies. International Code of Zoological Nomenclature_sentence_61

Primary homonyms are those with the same genus and same species in their original combination. International Code of Zoological Nomenclature_sentence_62

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. International Code of Zoological Nomenclature_sentence_63

Examples: International Code of Zoological Nomenclature_sentence_64

International Code of Zoological Nomenclature_description_list_9

  • Drury (1773) established Cerambyx maculatus (Coleoptera) for a species from Jamaica. 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.International Code of Zoological Nomenclature_item_9_21
  • 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 that clarified that different species were meant, and that their authors did not know that the name had been established by a previous author.International Code of Zoological Nomenclature_item_9_22

Secondary homonyms can be produced if taxa with the same specific name but different original genus are later classified in the same genus (Art. International Code of Zoological Nomenclature_sentence_65

57.3, 59). International Code of Zoological Nomenclature_sentence_66

A secondary synonym is only a temporary state, it is only effective in this classification. International Code of Zoological Nomenclature_sentence_67

If another classification is applied, the secondary homonymy may not be produced, and the involved name can be used again (Art. International Code of Zoological Nomenclature_sentence_68

59.1). International Code of Zoological Nomenclature_sentence_69

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. International Code of Zoological Nomenclature_sentence_70

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. International Code of Zoological Nomenclature_sentence_71

Example: International Code of Zoological Nomenclature_sentence_72

International Code of Zoological Nomenclature_description_list_10

  • Nunneley (1837) established Limax maculatus (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 Limax. This meant that L. maculatus Nunneley, 1837 and K. maculatus Kaleniczenko, 1851 were classified in the same genus, so both names were secondary homonyms in the genus Limax, and the younger name (from 1851) could not be used for the Ukrainian species. This made it necessary to look for the next younger available name that could be used for the Ukrainian species. This was Limax ecarinatus Boettger, 1881, a junior synonym of K. maculatus Kaleniczenko, 1851.International Code of Zoological Nomenclature_item_10_23
  • 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 Limacus as a separate genus, the name of the Ukrainian species must be Limacus maculatus (Kaleniczenko, 1851).International Code of Zoological Nomenclature_item_10_24
  • So the Ukrainian species can have two names, depending from its generic classification. Limax ecarinatus, Limacus maculatus, the same species.International Code of Zoological Nomenclature_item_10_25

Article 59.3 states that in exceptional cases, junior secondary homonyms replaced before 1961 by substitute names can become invalid, "...unless the substitute name is not in use," an exception of the exception. International Code of Zoological Nomenclature_sentence_73

However, the ICZN Code does not give an example for such a case. International Code of Zoological Nomenclature_sentence_74

It seems that this passage in the ICZN Code is widely ignored. International Code of Zoological Nomenclature_sentence_75

It also does not define what the expression "is not in use" should mean. International Code of Zoological Nomenclature_sentence_76

Example: International Code of Zoological Nomenclature_sentence_77

International Code of Zoological Nomenclature_description_list_11

  • Glischrus caelata Studer, 1820 (Gastropoda) was once classified in the genus Helix, 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 now known as Trochulus caelatus (Studer, 1820), and Art. 59.3 is commonly ignored.International Code of Zoological Nomenclature_item_11_26

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. International Code of Zoological Nomenclature_sentence_78

Examples: International Code of Zoological Nomenclature_sentence_79

International Code of Zoological Nomenclature_description_list_12

  • The name Noctua Linnæus, 1758 was established for a lepidopteran subgenus. In 1764 he established a genus Noctua Linné ,1764 for birds, ignoring that he had already used this name a few years ago in Lepidoptera. Noctua Linné, 1764 (Aves) is a junior homonym of Noctua Linnæus, 1758 (Lepidoptera).International Code of Zoological Nomenclature_item_12_27
  • Garsault (1764) used Noctua for a bird and established a name Garsault, 1764 (Aves). Fabricius (1775) established a name Noctua caprimulgus Fabricius, 1775 (Lepidoptera), thus creating a double homonym. Double homonymy is no homonymy, both names are available.International Code of Zoological Nomenclature_item_12_28
  • The same happened with Noctua variegata Jung, 1792 (Lepidoptera) and Noctua variegata Quoy & Gaimard, 1830 (Aves).International Code of Zoological Nomenclature_item_12_29

For disambiguating one genus-group name from its homonym, it is important to cite author and year. International Code of Zoological Nomenclature_sentence_80

Citing the author alone is often not sufficient. International Code of Zoological Nomenclature_sentence_81

Examples: International Code of Zoological Nomenclature_sentence_82

International Code of Zoological Nomenclature_description_list_13

  • Echidna Forster, 1777 (Actinopterygii), not Echidna Cuvier, 1797 (Mammalia)International Code of Zoological Nomenclature_item_13_30
  • Ansa Walker, 1858 (Lepidoptera), not Ansa Walker, 1868 (Hemiptera)International Code of Zoological Nomenclature_item_13_31
  • Helix balcanica Kobelt, 1876, not Helix balcanica Kobelt, 1903 (both Gastropoda)International Code of Zoological Nomenclature_item_13_32
  • Conus catenatus Sowerby, 1850, not Conus catenatus Sowerby, 1875 (both Gastropoda)International Code of Zoological Nomenclature_item_13_33

The name Ansa can only be used for a lepidopteran taxon. International Code of Zoological Nomenclature_sentence_83

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. International Code of Zoological Nomenclature_sentence_84

The only option to use the 1868 name for the hemipteran taxon is to get the 1858 name officially suppressed by the commission. International Code of Zoological Nomenclature_sentence_85

In some cases, the same genus-group or species-group name was published in the same year by the same author. International Code of Zoological Nomenclature_sentence_86

In these cases it is useful to cite the page where the name was established. International Code of Zoological Nomenclature_sentence_87

International Code of Zoological Nomenclature_description_list_14

  • Amydona Walker, 1855 (Lepidoptera: Limacodidae) (p. 1110), not Amydona Walker, 1855 (Lepidoptera: Lasiocampidae) (p. 1413)International Code of Zoological Nomenclature_item_14_34
  • Betousa Walker, 1865 (Lepidoptera: Thyridae) (p. 1111), not Betousa Walker, 1865 (Lepidoptera: Noctuidae) (p. 1208).International Code of Zoological Nomenclature_item_14_35
  • Cicada variegata Fabricius, 1775 (p. 684), not Cicada variegata Fabricius, 1775 (p. 686) (both Auchenorrhyncha).International Code of Zoological Nomenclature_item_14_36
  • Noctua marginata Fabricius, 1775 (p. 597), not Noctua marginata Fabricius, 1775 (p. 610) (both Lepidoptera: Noctuidae).International Code of Zoological Nomenclature_item_14_37
  • Clausilia (Albinaria) oertzeni Boettger, 1889 (p. 42), not Clausilia (Albinaria) schuchi var. oertzeni Boettger, 1889 (p. 52) (both Gastropoda: Clausiliidae).International Code of Zoological Nomenclature_item_14_38

There are cases where two homonyms were established by the same author in the same year on the same page: International Code of Zoological Nomenclature_sentence_88

International Code of Zoological Nomenclature_description_list_15

  • Zonites verticillus var. graeca Kobelt, 1876 (Gastropoda) (p. 48), not Zonites albanicus var. graeca Kobelt, 1876 (p. 48).International Code of Zoological Nomenclature_item_15_39

Animal, plant, and fungi nomenclature are entirely independent from each other. International Code of Zoological Nomenclature_sentence_89

The most evident shortcoming of this situation (for their use in biodiversity informatics) is that the same generic name can be used simultaneously for animals and plants. International Code of Zoological Nomenclature_sentence_90

For this kind of homonym the expression "hemihomonym" is sometimes used. International Code of Zoological Nomenclature_sentence_91

Far more than 1000 such names are known. International Code of Zoological Nomenclature_sentence_92

Examples: International Code of Zoological Nomenclature_sentence_93

International Code of Zoological Nomenclature_description_list_16

  • The generic name Dryas L. (1753) represents a genus of magnoliophytan plants (family Rosaceae), and at the same time Dryas Hübner, 1807 is also a lepidopteran insect genus (family Nymphalidae).International Code of Zoological Nomenclature_item_16_40
  • The genus Tandonia was established in animals (Gastropoda: Tandonia), in plants (Euphorbiaceae) and in Fungi (Ascomycetes).International Code of Zoological Nomenclature_item_16_41
  • 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).International Code of Zoological Nomenclature_item_16_42

For names above the family level, the principle of homonymy does not apply. International Code of Zoological Nomenclature_sentence_94

Examples: International Code of Zoological Nomenclature_sentence_95

International Code of Zoological Nomenclature_description_list_17

  • Pulmonata is usually used for a very prominent group in Gastropoda, but the name is also (rarely) used for a group in Arachnida.International Code of Zoological Nomenclature_item_17_43
  • Reticulata is used as an order in Foraminifera, and as an undefined higher group in Ephemeroptera.International Code of Zoological Nomenclature_item_17_44

Homonyms occur relatively rarely in families (only if generic names are identical or very similar and adding an ending "-idae" produces identical results). International Code of Zoological Nomenclature_sentence_96

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. International Code of Zoological Nomenclature_sentence_97

Very often the Commission must be asked to take a decision. International Code of Zoological Nomenclature_sentence_98

Examples: International Code of Zoological Nomenclature_sentence_99

International Code of Zoological Nomenclature_description_list_18

  • Bulimina (Foraminifera) and Buliminus (Gastropoda) give both Buliminidae, and both families were used since the 1880s. When the homonymy was discovered 110 years later in the 1990s, the younger (gastropod) taxon had to receive a new family name, and the commission needed was asked for a solution (Opinion 2018).International Code of Zoological Nomenclature_item_18_45
  • Claria (Rotifera) and Clarias (Actinopterygii) give both Clariidae, but only the actinopterygian fish name was used since 1845. Shortly after Clariidae had been proposed in Rotifera in 1990, the homonymy was discovered and the commission had to decide that the Rotiferan family had to be amended to Clariaidae (Opinion 2032).International Code of Zoological Nomenclature_item_18_46

Principle of typification International Code of Zoological Nomenclature_section_6

Main article: Principle of Typification International Code of Zoological Nomenclature_sentence_100

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. International Code of Zoological Nomenclature_sentence_101

This means that any named taxon has a name-bearing type, which allows the objective application of that name. International Code of Zoological Nomenclature_sentence_102

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. International Code of Zoological Nomenclature_sentence_103

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). International Code of Zoological Nomenclature_sentence_104

Example: International Code of Zoological Nomenclature_sentence_105

International Code of Zoological Nomenclature_description_list_19

  • The family name Spheniscidae has as its type genus the genus Spheniscus Brisson, 1760.International Code of Zoological Nomenclature_item_19_47

The type species for a genus-group name is more complicated and follows exactly defined provisions in articles 67–69. International Code of Zoological Nomenclature_sentence_106

Type species are very important, and no general zoological database has recorded the type species for all genera. International Code of Zoological Nomenclature_sentence_107

Except in fishes and some minor groups, type species are rarely reliably recorded in online animal databases. International Code of Zoological Nomenclature_sentence_108

In 60% of the cases the type species can be determined in the original publication. International Code of Zoological Nomenclature_sentence_109

The type species is always the original name of the taxon (and not the currently used combination). International Code of Zoological Nomenclature_sentence_110

Example: International Code of Zoological Nomenclature_sentence_111

International Code of Zoological Nomenclature_description_list_20

  • The correctly cited type species of Locusta Linnæus, 1758 (Caelifera) is Gryllus migratorius Linnæus, 1758, not Locusta migratoria (Linnæus, 1758).International Code of Zoological Nomenclature_item_20_48

Designation and fixation have different meanings. International Code of Zoological Nomenclature_sentence_112

A designation is the proposal of the type species. International Code of Zoological Nomenclature_sentence_113

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. International Code of Zoological Nomenclature_sentence_114

If the designation is valid, the type species is fixed. International Code of Zoological Nomenclature_sentence_115

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. International Code of Zoological Nomenclature_sentence_116

There are various possible modes of type species designation. International Code of Zoological Nomenclature_sentence_117

This is their order of legal importance, with approximate proportions of occurrence and examples: International Code of Zoological Nomenclature_sentence_118

International Code of Zoological Nomenclature_unordered_list_21

  • Superior type fixation:International Code of Zoological Nomenclature_item_21_49

International Code of Zoological Nomenclature_description_list_22

  • International Code of Zoological Nomenclature_item_22_50
    • Designation by ICZN under the plenary powers (3 %)International Code of Zoological Nomenclature_item_22_51
      • Example:International Code of Zoological Nomenclature_item_22_52
      • 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).International Code of Zoological Nomenclature_item_22_53
    • Designation under Art. 70.3 (misidentified type species) (1 %)International Code of Zoological Nomenclature_item_22_54
      • Examples:International Code of Zoological Nomenclature_item_22_55
      • 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.International Code of Zoological Nomenclature_item_22_56
      • 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.International Code of Zoological Nomenclature_item_22_57

International Code of Zoological Nomenclature_unordered_list_23

  • Type fixation in the original work:International Code of Zoological Nomenclature_item_23_58

International Code of Zoological Nomenclature_description_list_24

  • International Code of Zoological Nomenclature_item_24_59
    • Original designation (31 %)International Code of Zoological Nomenclature_item_24_60
    • Monotypy (28 %)International Code of Zoological Nomenclature_item_24_65
      • Examples:International Code of Zoological Nomenclature_item_24_66
      • Anodonta Lamarck, 1799 (Bivalvia) was originally established with one included nominal species, Mytilus cygneus Linnæus, 1758. This is the type species fixed by monotypy (now Anodonta cygnea).International Code of Zoological Nomenclature_item_24_67
      • 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).International Code of Zoological Nomenclature_item_24_68
    • Absolute tautonymy (2 %)International Code of Zoological Nomenclature_item_24_69
    • Linnean tautonymy (0.3 %)International Code of Zoological Nomenclature_item_24_76
      • Example:International Code of Zoological Nomenclature_item_24_77
      • Linnæus 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 Linnæus 1758 is type species fixed by Linnean tautonymy (now Castor fiber).International Code of Zoological Nomenclature_item_24_78

International Code of Zoological Nomenclature_unordered_list_25

  • Subsequent methods of type fixation:International Code of Zoological Nomenclature_item_25_79

International Code of Zoological Nomenclature_description_list_26

  • International Code of Zoological Nomenclature_item_26_80
    • Subsequent monotypy (2 %)International Code of Zoological Nomenclature_item_26_81
      • Examples:International Code of Zoological Nomenclature_item_26_82
      • 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).International Code of Zoological Nomenclature_item_26_83
      • Omphiscola Rafinesque, 1819 (Gastropoda) was established without species included. Beck 1837 included one species Buccinum glabrum Müller, 1774. Buccinum glabrum is type species by subsequent monotypy (now Omphiscola glabra).International Code of Zoological Nomenclature_item_26_84
    • Subsequent absolute tautonymy (only very few cases)International Code of Zoological Nomenclature_item_26_85
    • Subsequent Linnean tautonymy (only theoretical, there might be no case)International Code of Zoological Nomenclature_item_26_89
    • Subsequent designation (32 %)International Code of Zoological Nomenclature_item_26_90

A species-group name can have a name-bearing type specimen, but this is not a requirement. International Code of Zoological Nomenclature_sentence_119

In many cases species-group names have no type specimens, or they are lost. International Code of Zoological Nomenclature_sentence_120

In those cases the application of the species-group name is usually based on common acceptance. International Code of Zoological Nomenclature_sentence_121

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. International Code of Zoological Nomenclature_sentence_122

Fixing such a name-bearing type should only be done if this is taxonomically necessary (articles 74.7.3, 75.2, 75.3). International Code of Zoological Nomenclature_sentence_123

Examples: International Code of Zoological Nomenclature_sentence_124

International Code of Zoological Nomenclature_description_list_27

  • 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.International Code of Zoological Nomenclature_item_27_94
  • The name-bearing type for Homo sapiens Linnæus, 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.International Code of Zoological Nomenclature_item_27_95

Structure International Code of Zoological Nomenclature_section_7

The code divides names in the following manner: International Code of Zoological Nomenclature_sentence_125

International Code of Zoological Nomenclature_unordered_list_28

  • Names above the family groupInternational Code of Zoological Nomenclature_item_28_96
  • Family-group namesInternational Code of Zoological Nomenclature_item_28_97
  • Genus-group namesInternational Code of Zoological Nomenclature_item_28_98
  • Species-group namesInternational Code of Zoological Nomenclature_item_28_99

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. International Code of Zoological Nomenclature_sentence_126

The names in the family, genus, and species groups are fully regulated by the provisions in the code. International Code of Zoological Nomenclature_sentence_127

There is no limitation to the number of ranks allowed in the family group. International Code of Zoological Nomenclature_sentence_128

The genus group has only two ranks: genus and subgenus. International Code of Zoological Nomenclature_sentence_129

The species group has only two ranks: species and subspecies. International Code of Zoological Nomenclature_sentence_130

Gender agreement International Code of Zoological Nomenclature_section_8

In the species group gender agreement applies. International Code of Zoological Nomenclature_sentence_131

The name of a species, in two parts, a binomen, say, Loxodonta africana, and of a subspecies, in three parts, a trinomen, say Canis lupus albus, is in the form of a Latin phrase, and must be grammatically correct Latin. International Code of Zoological Nomenclature_sentence_132

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. International Code of Zoological Nomenclature_sentence_133

If it is a noun, or an arbitrary combination of letters, this does not apply. International Code of Zoological Nomenclature_sentence_134

International Code of Zoological Nomenclature_unordered_list_29

  • 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.International Code of Zoological Nomenclature_item_29_100
  • In Equus zebra the specific name zebra is a noun, it may not be "corrected" to "Equus zebrus".International Code of Zoological Nomenclature_item_29_101
  • In Equus quagga burchellii the subspecific name burchellii is a noun in the genitive case ("of Burchell").International Code of Zoological Nomenclature_item_29_102

If a species is moved, therefore, the spelling of an ending may need to change. International Code of Zoological Nomenclature_sentence_135

If Gryllus migratorius is moved to the genus Locusta, it becomes Locusta migratoria. International Code of Zoological Nomenclature_sentence_136

Confusion over Latin grammar has led to many incorrectly formed names appearing in print. International Code of Zoological Nomenclature_sentence_137

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). International Code of Zoological Nomenclature_sentence_138

History International Code of Zoological Nomenclature_section_9

Written nomenclatural rules in zoology were compiled in various countries since the late 1830s, such as Merton's Rules and Strickland's codes going back to 1843. International Code of Zoological Nomenclature_sentence_139

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. International Code of Zoological Nomenclature_sentence_140

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). International Code of Zoological Nomenclature_sentence_141

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). International Code of Zoological Nomenclature_sentence_142

These were only published in English, and can only be found in the reports of these congresses or other official publications. International Code of Zoological Nomenclature_sentence_143

The 1905 rules became increasingly outdated. International Code of Zoological Nomenclature_sentence_144

They soon sold out, and it became increasingly difficult to obtain to a complete set of the Rules with all amendments. International Code of Zoological Nomenclature_sentence_145

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. International Code of Zoological Nomenclature_sentence_146

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. International Code of Zoological Nomenclature_sentence_147

The second edition of the code (only weakly modified) came in 1963. International Code of Zoological Nomenclature_sentence_148

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. International Code of Zoological Nomenclature_sentence_149

The third edition of the code came out in 1985. International Code of Zoological Nomenclature_sentence_150

The present edition is the 4th edition, effective since 2000. International Code of Zoological Nomenclature_sentence_151

These code editions were elaborated on by editorial committees appointed by the International Commission on Zoological Nomenclature. International Code of Zoological Nomenclature_sentence_152

The ICZN Commission takes its power from a general biological congress (IUBS, International Union of Biological Sciences). International Code of Zoological Nomenclature_sentence_153

The editorial committee for the fourth edition was composed of seven persons. International Code of Zoological Nomenclature_sentence_154

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. International Code of Zoological Nomenclature_sentence_155

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. International Code of Zoological Nomenclature_sentence_156

The Code consists of the original text of the fourth edition and Declaration 44. International Code of Zoological Nomenclature_sentence_157

The code is published in an English and a French version; both versions are official and equivalent in force, meaning, and authority. International Code of Zoological Nomenclature_sentence_158

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. International Code of Zoological Nomenclature_sentence_159

Commission International Code of Zoological Nomenclature_section_10

The rules in the code apply to all users of zoological names. International Code of Zoological Nomenclature_sentence_160

However, its provisions can be interpreted, waived, or modified in their application to a particular case when strict adherence would cause confusion. International Code of Zoological Nomenclature_sentence_161

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. International Code of Zoological Nomenclature_sentence_162

The commission takes such action in response to proposals submitted to it. International Code of Zoological Nomenclature_sentence_163

International Code of Zoological Nomenclature_unordered_list_30

  • Carl Linnaeus named the domestic cat Felis catus in 1758; Johann Christian Daniel von Schreber named the wildcat Felis silvestris in 1775. For taxonomists who consider these two kinds of cat a single species the principle of priority means that the species ought to be named F. catus, but in practice almost all biologists have used F. silvestris. In 2003, the commission issued a ruling (Opinion 2027) that "conserved the usage of 17 specific names based on wild species, which are pre-dated, by or contemporary with those based on domestic forms", confirming F. silvestris for the wild cat. Taxonomists who consider the domesticated cat the same species as the wild cat should use F. silvestris; taxonomists who consider the domesticated cat a subspecies of the wild cat should use F. silvestris catus; taxonomists who consider the domesticated cat a separate species should use F. catus.International Code of Zoological Nomenclature_item_30_103

The latest amendments enacted by the commission concern electronic publishing, which is now permitted for works published under an ISBN or ISSN after 2011 in a way that ensures registration with ZooBank as well as archival of multiple copies. International Code of Zoological Nomenclature_sentence_164

Local usage and name changes International Code of Zoological Nomenclature_section_11

The ICZN is used by the scientific community worldwide. International Code of Zoological Nomenclature_sentence_165

Changes are governed by guidelines in the code. International Code of Zoological Nomenclature_sentence_166

Local changes, such as the changes proposed by the Turkish government, are not recognised by ICZN. International Code of Zoological Nomenclature_sentence_167

Citation International Code of Zoological Nomenclature_section_12

The current (fourth edition) code is cited in scientific papers as ICZN (1999) and in reference lists as:- International Code of Zoological Nomenclature_sentence_168

ICZN 1999. International Code of Zoological Nomenclature. International Code of Zoological Nomenclature_sentence_169

Fourth Edition. International Code of Zoological Nomenclature_sentence_170

The International Trust for Zoological Nomenclature, London, UK. International Code of Zoological Nomenclature_sentence_171

306 pp. International Code of Zoological Nomenclature_sentence_172

Versions International Code of Zoological Nomenclature_section_13

International Code of Zoological Nomenclature_unordered_list_31

  • 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. . [Also published in the Philosophical Magazine and the Annals of Natural History.]International Code of Zoological Nomenclature_item_31_104
  • Strickland, H.E. 1878. Rules for Zoological Nomenclature. John Murray, London. .International Code of Zoological Nomenclature_item_31_105
  • 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. .International Code of Zoological Nomenclature_item_31_106
  • ICZN. 1961. International Code of Zoological Nomenclature: adopted by the XV International Congress of Zoology. The International Trust for Zoological Nomenclature, London, UK. .International Code of Zoological Nomenclature_item_31_107
  • ICZN. 1964. International Code of Zoological Nomenclature. Second edition. The International Trust for Zoological Nomenclature, London, UK. .International Code of Zoological Nomenclature_item_31_108
  • ICZN. 1985. International Code of Zoological Nomenclature. Third edition. The International Trust for Zoological Nomenclature, London, UK. .International Code of Zoological Nomenclature_item_31_109
  • ICZN. 1999. International Code of Zoological Nomenclature. Fourth edition. The International Trust for Zoological Nomenclature, London, UK. . .International Code of Zoological Nomenclature_item_31_110

See also International Code of Zoological Nomenclature_section_14

International Code of Zoological Nomenclature_unordered_list_32

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: Code of Zoological Nomenclature.