The nominal author(s) of a clade name is (are) the person(s) who first published the name (but see Notes 9.15A.1, 19.1.1), regardless of whether it was phylogenetically defined and regardless of whether it was initially applied to a taxon that differed somewhat in composition from the clade for which the name is being converted (provided that it is not a homonym; see Note 9.15A.2). The definitional author(s) of a clade name is (are) the person(s) who established that name, including publication of a phylogenetic definition for it (either the original definition or an emended one), under this code.
When determining nominal authorship, publications before the nomenclatural starting point for the particular group of organisms under the appropriate rank-based code are not considered.
For a new clade name (except a new replacement name), the nominal and definitional authors are the same. For a converted clade name or a replacement name, the nominal and definitional authors are frequently different.
The ICNAFP (Art. 39) requires that new taxon names (other than for fossils) published from 1935 through 2011 be accompanied by a Latin description or diagnosis or a reference to the same. By contrast, this code does not require a Latin description or diagnosis for the establishment of a name. Therefore, a person who published a preexisting botanical name with a description or diagnosis and otherwise satisfying the ICNAFP rules for a legitimate name (see Art. 6.2) may be considered the nominal author, regardless of whether the description or diagnosis was in Latin (although there are situations in which such a person might not be considered the nominal author; see Note 9.15A.1, Ex. 1).
A clade name or definition is to be attributed to the author(s) of the protologue, even though authorship of the publication as a whole may be different.
In some cases, a breadth of evidence may need to be considered to determine the correct author attribution, including ascription of the name, statements in the introduction, title, or acknowledgements, typographical distinctions in the text, and even statements made in other volumes and editions in the same series or in entirely different publications.
In the absence of evidence to the contrary, the authorship of the protologue can be assumed to be the same as the authorship of the entire publication in which it appears.
The nominal authors of a replacement name are the authors of that name, not the authors of the replaced name. However, because the definition remains the same (Art. 13.5), the definitional authors of the replacement name are the definitional authors of the replaced name.
A preexisting clade name is to be attributed to the author(s) of the protologue when only the name, but not the rest of the protologue, is attributable to (a) different author(s) (see Art. 20.8).
When the prevailing spelling of a preexisting name differs from the original spelling due to correction of orthographic or typographical errors in the original spelling or orthographic standardizations, whether imposed by a rank-based code or accepted by convention, the prevailing spelling is to be attributed to the author of the publication in which the original spelling was used.
Iguana, which is the prevailing spelling of the name, is attributed to Linnaeus even though he used the spelling Igvana in the original publication.
Article 19.5 does not apply to names whose spellings have been “corrected” under a rank-based code to the standard ending for the rank at which it was published (see Note 9.15A.4).
Under this code, the name Hypericaceae is not attributed to Jussieu, who published Hyperica as a family name, even though Hypericaceae is considered to be a “correction” of Hyperica under the ICNAFP, i.e., through addition of the standard ending for plant families (see Note 9.15A.4, Ex. 1).