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The PhyloCode
Chapter IX. Citation of Authors and Registration Numbers
Article 20.
20.1. Citation of nominal and definitional authors (Art 19.1) is optional, but if authors are cited, Arts. 20.220.8 are to be followed.
20.2. Authors' names are to be cited after the clade name. Nominal authors of any name, whether preexisting or new, are to be cited without enclosing symbols. Definitional authors are to be cited within enclosing symbols. The author of the original definition (i.e., the definitional author of a new or converted name) is to be cited in square brackets ([ ]; Art. 20.4, Example 1). The author of an emended definition is to be cited in braces ({ }; Art. 20.6, Example 1).
20.3. If more than one author is cited, they are to be cited in the following order: nominal author of the preexisting or new name (including a replacement name); author of the original definition; author of an emended definition.
20.4. If the definitional author of a converted name is cited, the nominal author of the preexisting name on which it is based, if known, must also be cited.
Example 1. Suppose that Larson established a converted clade name Hypotheticus in 2010 based on the preexisting name Hypotheticus of Meekins (published in 1956). In this situation, the citation of the converted name would be Hypotheticus Meekins [Larson]. Meekins is the nominal author; Larson is the definitional author.
Example 2. If Larson established a converted clade name Hypotheticus based on the preexisting name Hypotheticus, and if the authorship of this name were unknown, the citation of the converted name would be Hypotheticus [Larson].
Note 20.4.1. The publication years of the preexisting name and converted name may follow the names of the respective authors.
Example 1. Using Example 1 of Art. 20.4, the citation with publication years would be Hypotheticus Meekins 1956 [Larson 2010].
Recommendation 20.4A. If a preexisting name was used in association with more than one rank or composition, and authorship is cited, the nominal author cited should be the original author of the name, as spelled for the purpose of conversion, rather than the first author who applied the name later in association with a different rank or composition (but see Rec. 9.8A).
Recommendation 20.4B. If a preexisting name has been attributed to an author other than the first author who used the name being converted (as can occur under the Principle of Coordination of the ICZN), the nominal author cited should not be the former but rather the author of the name as spelled for the purpose of conversion (but see Note 9.8A.2 and its Example 1.)
20.5. If the nominal author of a replacement name is cited, the definitional author of the replacement name (i.e., the definitional author of the replaced name; see Arts. 13.5, 19.3) must also be cited.
Example 1. Suppose that Holmes was the definitional author of the name Cladus, which turned out to be a later homonym of Cladus (established by a different author), and then Clarke published the new name Imaginarius as a replacement name for Cladus Holmes. The full citation of the replacement name would be Imaginarius Clarke [Holmes]. If, instead, Clarke had converted the replacement name from the preexisting name Fabricatus Merriam, the full citation of the replacement name would be Fabricatus Merriam [Holmes].
20.6. If the author of an emended definition (see Art. 15) is cited, the author of the original definition must also be cited.
Example 1. If Fictitius was established as a new name by Stein, and Maki subsequently emended Stein's definition, the full citation would be Fictitius Stein {Maki}. If, instead, Stein had converted Fictitius from the preexisting name Fictitius Merriam, the full citation would be Fictitius Merriam [Stein] {Maki}.
20.7. When authorship of a name differs from authorship of the publication in which it is established, both may be cited, connected by the word "in." In such a case, "in" and what follows are part of a bibliographic citation and are only to be included if the publication is referred to, at least by its year.
20.8. The optional use of "ex" under the ICBN to cite author(s) to whom the name, but not the rest of the protologue, is attributable is not adopted in this code.
Recommendation 20A. Bibliographic references to the protologue of established names are available in the registration database and may be accessed by either clade name or registration number. However, only the registration number is reliably unique. Therefore, in cases of potential ambiguity, the registration number should be cited at least once in any publication in which the corresponding name is used.