Article 11. Requirements. To be available, a name or, where relevant, a nomenclatural act must satisfy the following provisions:

11.1. Publication. The name or nomenclatural act must have been published, in the meaning of Article 8, after 1757.

11.2. Mandatory use of Latin alphabet. A scientific name must, when first published, have been spelled only in the 26 letters of the Latin alphabet (taken to include the letters j, k, w and y); the presence in a name when first published of diacritic and other marks, apostrophes or ligatures, or a hyphen, or a numeral in a compound species-group name, does not render the name unavailable (for corrections, see Articles 27 and 32.5.2).

11.3. Derivation. Providing it meets the requirements of this Chapter, a name may be a word in or derived from Latin, Greek or any other language (even one with no alphabet), or be formed from such a word. It may be an arbitrary combination of letters providing this is formed to be used as a word.

Examples. Toxostoma and brachyrhynchos from the Greek; opossum from the Algonquian Indian; Abudefduf from the Arabic; korsac from the Russian; nakpo from the Tibetan; canguru from the Kokoimudji Aboriginal; Gythemon, an arbitrary combination of letters. The arbitrary combination of letters cbafdg cannot be used as a word and does not form a name.

Recommendation 11A. Use of vernacular names. An unmodified vernacular word should not be used as a scientific name. Appropriate latinization is the preferred means of formation of names from vernacular words.

11.4. Consistent application of binominal nomenclature. The author must have consistently applied the Principle of Binominal Nomenclature [Art. 5.1] in the work in which the name or nomenclatural act was published; however, this Article does not apply to the availability of names of taxa at ranks above the family group.

11.4.1. A published work containing family-group names or genus-group names without associated nominal species is accepted as consistent with the Principle of Binominal Nomenclature in the absence of evidence to the contrary.

11.4.2. The scientific name of a subspecies, a trinomen [Art. 5.2], is accepted as consistent with the Principle of Binominal Nomenclature.

11.4.3. An index published before 1931 in a work that is not consistently binominal is acceptable itself as a work consistent with the Principle of Binominal Nomenclature provided that the Principle is consistently applied to scientific names in the index; thus a scientific name published in such an index is available if the name satisfies the other provisions of this Chapter and of Articles 4, 5 and 6, and if there is an unambiguous link between the entry in the index and the description, illustration, or indication in the text.

11.5. Names to be used as valid when proposed. To be available, a name must be used as valid for a taxon when proposed, unless it was first published as a junior synonym and subsequently made available under the provisions of Article 11.6.1.

11.5.1. A name proposed conditionally for a taxon before 1961 is not to be excluded on that account alone [Art. 15].

11.5.2. The status of a previously unavailable name is not changed by its mere citation (that is, without adoption for a taxon) even if accompanied by a reference to the work in which the name was published but was not made available.

Example. Chemnitz in 1780 described the gastropod Conus moluccensis and treated its name as valid, but in a work which was not consistently binominal and thus the name is unavailable. Dillwyn in 1817 cited the name Conus moluccensis, but did not use it as the valid name of a taxon. The name Conus moluccensis is not made available by Dillwyn's act, even though his citation was accompanied by a reference to Chemnitz's work. Küster (1838) applied the name to a taxon and attributed it to Chemnitz by bibliographic reference, thereby making the name Conus moluccensis Küster, 1838 available.

11.6. Publication as a synonym. A name which when first published in an available work was treated as a junior synonym of a name then used as valid is not thereby made available.

11.6.1. However, if such a name published as a junior synonym had been treated before 1961 as an available name and either adopted as the name of a taxon or treated as a senior homonym, it is made available thereby but dates from its first publication as a synonym (for type species if a genus-group name see Article 67.12; for name-bearing type if a species-group name see Article 72.4.3; for authorship see Article 50.7).

Examples. Meigen (1818), in discussion under Ceratopogon flavipes Meigen (Diptera), stated that he had received the material from Megerle under the manuscript name Palpomyia geniculata. Palpomyia, there published as a synonym of Ceratopogon, is an available name because before 1961 it was used as a valid name; it is attributed to Meigen, 1818. The specific name geniculata, never having been adopted, is not available from Meigen (1818).

11.6.2. A name published before 1758 but after 1757 cited as a synonym of a name used as valid cannot be made available under Article 11.6.

Example. The name "Cidaris miliaris Klein" (i.e. of Klein, 1734) cited by Linnaeus (1758) in the synonymy of Echinus esculentus Linnaeus, 1758 does not become available from Linnaeus (1758) as a result of its mere adoption for a taxon by another author.

11.6.3. A name first published after 1960 and treated as a junior synonym on that occasion cannot be made available from that act under Article 11.6.

11.7. Family-group names.

11.7.1. A family-group name when first published must meet all the following criteria. It must:

11.7.1.1. be a noun in the nominative plural formed from the stem of an available generic name [Art. 29] (indicated either by express reference to the generic name or by inference from its stem, but for family-group names proposed after 1999 see Article 16.2); the generic name must be a name then used as valid in the new family-group taxon [Arts. 63, 64] (use of the stem alone in forming the name is accepted as evidence that the author used the generic name as valid in the new family-group taxon unless there is evidence to the contrary);

Examples. The name ERYCIINAE Robineau-Desvoidy, 1830 (originally spelled ERYCINAE) is available because it was published for a family-group taxon that included the genus Erycia Robineau-Desvoidy, 1830. The name TRICHOCERIDAE Rondani, 1841 is available, although proposed without explicit mention of Trichocera Meigen, 1803, because it was published in a classification of the families of the Diptera of Europe with reference to Meigen and with a clear statement of Rondani's basic principle of forming all family names on the name of an included genus. PINNIDAE Leach, 1819 included not only Modiola Lamarck, 1801 and Mytilus Linnaeus, 1758, but also, by inference from the stem, Pinna Linnaeus, 1758, for which it was obviously founded; it is available.

The name "Macromydae" of Robineau-Desvoidy (1830) is not available because, although a formal latinized group name (not a vernacular), it was a descriptive term for a group of genera that did not include Macromya Robineau-Desvoidy, 1830, a genus placed in context in a different and distant division of the family Tachinidae.

11.7.1.2. be clearly used as a scientific name to denote a suprageneric taxon and not merely as a plural noun or adjective referring to the members of a genus;

Example. Osten Sacken (1882) published a key to eleven species of the dipteran genus Graptomyza under the heading "Graptomyzae of the Indo-Malayan Archipelago". The word "Graptomyzae" is a plural noun referring only to "the species of the genus Graptomyza"; it is not available as a family-group name.

11.7.1.3. end with a family-group name suffix except as provided in Article 11.7.2; a family-group name of which the family-group name suffix [Art. 29.2] is incorrect is available with its original authorship and date, but with a corrected suffix [Arts. 29, 32.5.3];

Example. Latreille (1802) established a family Tipulariae, based on Tipula Linnaeus, 1758. The suffix -ariae is corrected to -IDAE; TIPULIDAE is attributed to Latreille, not to the author who first corrected the spelling.

11.7.1.4. not be based on certain names applied only to fossils and ending in the suffix -ites, -ytes or -ithes [Art. 20];

11.7.1.5. not be based on a genus-group name that has been suppressed by the Commission [Art. 78].

11.7.2. If a family-group name was published before 1900, in accordance with the above provisions of this Article but not in latinized form, it is available with its original author and date only if it has been latinized by later authors and has been generally accepted as valid by authors interested in the group concerned and as dating from that first publication in vernacular form.

Example. The mite family name TETRANYCHIDAE is generally attributed to Donnadieu, 1875. He published the name as "Tétranycidés", but in view of the general acceptance of TETRANYCHIDAE from 1875 it is to be attributed to his work and date, not to Murray (1877), who first latinized it.

11.8. Genus-group names. A genus-group name (see also Article 10.3) must be a word of two or more letters and must be, or be treated as, a noun in the nominative singular.

11.8.1. A genus-group name proposed in Latin text but written otherwise than in the nominative singular because of the requirements of Latin grammar is available, provided that it meets the other requirements of availability, but it is to be corrected to the nominative singular.

Example. The generic name Diplotoxa (Diptera) was proposed by Loew (1863) in a note under "Chlorops versicolor nov. sp." as follows: "Chlor. versicolor cum similibus proprium genus ... constituit, cui nomen Diplotoxae propono" [Chlor. versicolor and similar species constitute a separate genus, for which I propose the name of Diplotoxa].

11.9. Species-group names.

11.9.1. A species-group name must be a word of two or more letters, or a compound word (see Article 11.9.5), and, if a Latin or latinized word must be, or be treated as,

11.9.1.1. an adjective or participle in the nominative singular (as in Echinus esculentus, Felis marmorata, Seioptera vibrans), or

11.9.1.2. a noun in the nominative singular standing in apposition to the generic name (as in Struthio camelus, Cercopithecus diana), or

11.9.1.3. a noun in the genitive case (e.g. rosae, sturionis, thermopylarum, galliae, sanctipauli, sanctaehelenae, cuvieri, merianae, smithorum), or

11.9.1.4. an adjective used as a substantive in the genitive case and derived from the specific name of an organism with which the animal in question is associated (as in Lernaeocera lusci, a copepod parasitic on Trisopterus luscus).

11.9.2. An adjectival species-group name proposed in Latin text but written otherwise than in the nominative singular because of the requirements of Latin grammar is available provided that it meets the other requirements of availability, but it is to be corrected to the nominative singular if necessary.

Example. Accompanying his treatment of the species Musca grossa and M. tremula, Illiger (1807) described a new fly stating "... species occurrit, Grossae et Tremulae intermedia ... quam Pavidam nuncupamus" [there is a species intermediate between M. grossa and M. tremula, which is here called pavida]. The specific name published in the accusative case as pavidam is corrected to the nominative pavida.

11.9.3. A species-group name must be published in unambiguous combination with a generic name (either explicit, or implicit by context);

Example. In the Example to Article 11.9.2 above, the combinations are not revealed explicitly by juxtaposition, or language (i.e. the use of Latin names distinct from the rest of the text), but are clear from the context. The specific name pavida is taken to have been published in combination with Musca.

11.9.3.1. the generic name need not be valid or even available;

11.9.3.2. a species-group name is deemed to have been published in combination with the correct original spelling of the generic name, even if it was actually published in combination with an emendation or incorrect spelling of the generic name [Art. 33];

11.9.3.3. the generic name may be cited as an abbreviation providing it is unambiguous in the context in which the new species-group name is published;

11.9.3.4. the generic combination, although it must be unambiguous, can be tentative;

Example. In the binomen Dysidea? papillosa Johnston, 1842, the tentative generic combination does not affect the availability of the specific name.

11.9.3.5. a species-group name first published as an interpolated name [Art. 6.2] cannot be made available from that act;

11.9.3.6. a species-group name first published before 1961 in combination with a previously available generic name, but accompanied in the same work by a new nominal genus conditionally proposed [Art. 15] to contain the new species or subspecies, is deemed to have been made available in combination with the previously available generic name (see Articles 15.1 and 51.3.3).

Example. Lowe (1843) established the new fish species Seriola gracilis and at the same time conditionally proposed a new genus Cubiceps to contain that nominal species. By that action he is deemed to have established first the nominal species Seriola gracilis Lowe, 1843 and then to have transferred it to the conditionally proposed genus Cubiceps, in which its name is cited as Cubiceps gracilis (Lowe, 1843).

11.9.4. A species-group name must not consist of words related by a conjunction nor include a sign that cannot be spelled out in the Latin alphabet (see Article 11.2; for the use of the hyphen, see Article 32.5.2.4.3).

Examples. Expressions like "rudis planusque" (in which "-que" is a conjunction) and "?-album" are not admissible as species-group names.

11.9.5. If a species-group name is published as separate words that together represent or refer to a single entity (e.g. host species, geographical area), in a work in which the author has otherwise consistently applied the Principle of Binominal Nomenclature [Art. 5.1], the component words are deemed to form a single word and are united without a hyphen [Art. 32.5.2.2].

Examples. The specific names in Coluber novaehispaniae, Calliphora terraenovae and Cynips quercusphellos (the last named based on the binominal name of the host plant) were originally published as two words, but they are admissible because together they denote a single entity. However, the words "aquilegiae flava" in Aphis aquilegiae flava (i.e. the yellow aphis of Aquilegia) do not form an admissible species-group name because they are a descriptive phrase not based on the name of a single entity.

11.10. Deliberate employment of misidentifications. If an author employs a specific or subspecific name for the type species of a new nominal genus-group taxon, but deliberately in the sense of a previous misidentification of it, then the author's employment of the name is deemed to denote a new nominal species and the specific name is available with its own author and date as though it were newly proposed in combination with the new genus-group name (see Article 67.13 for fixation as type species of a species originally included as an expressly stated earlier misidentification, and Article 69.2.4 for the subsequent designation of such a species as the type species of a previously established nominal genus or subgenus).

Example. Leach (1817) when establishing the nominal genus Plea (Heteroptera) fixed Notonecta minutissima as the type species by monotypy, but he expressly employed the name N. minutissima in the sense of a misidentification used by Geoffroy in Fourcroy (1785) and other authors and not in the taxonomic sense of Linnaeus (1758), the original author of the binomen. By that act Leach is deemed to have established the new nominal species Plea minutissima Leach, 1817 for the taxon actually involved and to have fixed this (and not Notonecta minutissima Linnaeus, 1758) as the type species of Plea.