Article 22. Citation of date. When cited, the date of publication of a name follows the name of the author (see Article 51).
Recommendation 22A. Citation.
22A.1. Citation of date. It is strongly recommended that the date of publication (and the authorship; see Article 50) of a name be cited at least once in a work which deals with a taxon. This is particularly important for homonyms and for species-group names not in their original combinations.
22A.2. Method of citation. In citing the date of publication of a name, an author
22A.2.1. should not interpose more than a comma between the name of the author and the date;
22A.2.2. if the actual date of publication is different from the date specified in the work (imprint date), should cite the actual date of publication; except that
22A.2.3. if wishing to cite both the actual and the imprint dates, should first cite the actual date (cited as above), followed by the imprint date for information and enclosed in parentheses or other brackets and quotation marks; for a different use of parentheses for the dates of family-group replacement names maintained under Article 40.2.1, see Recommendation 40A.
Examples. Ctenotus alacer Storr, 1970 ("1969"), or Ctenotus alacer Storr, 1970 ["1969"], or Ctenotus alacer Storr, 1970 (imprint 1969), or Ctenotus alacer Storr, 1970 (not 1969), was established in a work which, although published in 1970, carried an imprint date of 1969; Anomalopus truncatus (Peters, 1876 ["1877"]) was established in a different genus from Anomalopus in a work which, although published in 1876, carried an imprint date of 1877.
22A.3. Date in a changed combination. When the original date of publication of a species-group name is cited with the name in a changed combination, the date should be enclosed within the same parentheses as the name of the original author [Art. 51.3].
Example. Limax ater Linnaeus, 1758 should be cited as Arion ater (Linnaeus, 1758) when the species is included in the genus Arion.