CHAPTER II. Status, typification, and priority of names
SECTION 4. Limitation of the principle of priority
- In order to avoid disadvantageous nomenclatural changes entailed by the strict application of the rules, and especially of the principle of priority in starting from the dates given in Art. 13, this Code provides, in App. II–IV, lists of names of families, genera, and species that are conserved (nomina conservanda) (see Rec. 50E.1). Conserved names are legitimate even though initially they may have been illegitimate. The name of a subdivision of a genus or of an infraspecific taxon may be conserved with a conserved type and listed in App. III and IV, respectively, when it is the basionym of a name of a genus or species that could not continue to be used in its current sense without conservation.
- Conservation aims at retention of those names that best serve stability of nomenclature.
- The application of both conserved and rejected names is determined by nomenclatural types. The type of the species name cited as the type of a conserved generic name may, if desirable, be conserved and listed in App. III.
- A conserved name of a family or genus is conserved against all other names in the same rank based on the same type (homotypic, i.e. nomenclatural, synonyms, which are to be rejected) whether or not these are cited in the corresponding list as rejected names, and against those names based on different types (heterotypic, i.e. taxonomic, synonyms) that are listed as rejected1. A conserved name of a species is conserved against all names listed as rejected, and against all combinations based on the rejected names.
- Except as by Art. 14.15 (see also Art. 14.9), the Code does not provide for conservation of a name against itself, i.e. against an “isonym” (Art. 6 Note 2: the same name with the same type but with a different place and date of valid publication and perhaps with a different author). Only the earliest known isonyms are listed in App. IIA, III, and IV.
- A species name listed as conserved or rejected in App. IV may have been published as the name of a new taxon, or as a combination based on an earlier name. Rejection of a name based on an earlier name does not in itself preclude the use of the earlier name since that name is not “a combination based on a rejected name” (Art. 14.4).
- When a conserved name competes with one or more names based on different types and against which it is not explicitly conserved, the earliest of the competing names is adopted in accordance with Art. 11, except for the conserved family names listed in App. IIB, which are conserved against unlisted names.
- If Mahonia Nutt. (1818) is united with Berberis L. (1753), the combined genus will bear the prior name Berberis, although Mahonia is conserved and Berberis is not.
- Nasturtium R. Br. (1812) was conserved only against the homonym Nasturtium Mill. (1754) and the homotypic (nomenclatural) synonym Cardaminum Moench (1794); consequently if reunited with Rorippa Scop. (1760) it must bear the name Rorippa.
- Combretaceae R. Br. (1810) is conserved against the unlisted earlier heterotypic name Terminaliaceae J. St.-Hil. (Expos. Fam. Nat. 1: 178. 1805).
- When a name of a taxon has been conserved against an earlier heterotypic synonym, the latter is to be restored, subject to Art. 11, if it is considered the name of a taxon at the same rank distinct from that of the conserved name.
- The generic name Luzuriaga Ruiz & Pav. (1802) is conserved against the earlier names Enargea Banks ex Gaertn. (1788) and Callixene Comm. ex Juss. (1789). If, however, Enargea is considered to be a separate genus, the name Enargea is retained for it.
- To preserve the name Roystonea regia (Kunth) O. F. Cook (1900), its basionym Oreodoxa regia Kunth (1816) is conserved against Palma elata W. Bartram (1791). However, the name R. elata (W. Bartram) F. Harper (1946) can be used for a species distinct from R. regia.
- A rejected name, or a combination based on a rejected name, may not be restored for a taxon that includes the type of the corresponding conserved name.
- The listed type and spelling of a conserved name (evident misspellings excepted) may only be changed by the procedure outlined in Art. 14.12.
- A name may be conserved with a different type from that designated by the author or determined by application of the Code (see also Art. 10.4). Such a name may be conserved either from its place of valid publication (even though the type may not then have been included in the named taxon) or from a later publication by an author who did include the type as conserved. In the latter case the original name and the name as conserved are treated as if they were homonyms (Art. 53), whether or not the name as conserved was accompanied by a description or diagnosis of the taxon named.
- Bromus sterilis L. (1753) has been conserved from its place of valid publication even though its conserved type, a specimen (Hubbard 9045, E) collected in 1932, was not originally included in Linnaeus’s species.
- Protea L. (1753) did not include the conserved type of the generic name, P. cynaroides (L.) L. (1771), which in 1753 was placed in the genus Leucadendron. Protea was therefore conserved from the 1771 publication, and Protea L. (1771), although not intended to be a new generic name and still including the original type elements, is treated as if it were a validly published homonym of Protea L. (1753).
- A conserved name, with any corresponding autonym, is conserved against all earlier homonyms. An earlier homonym of a conserved name is not made illegitimate by that conservation but is unavailable for use; if not otherwise illegitimate, it may serve as basionym of another name or combination based on the same type (see also Art. 55.3).
- The generic name Smithia Aiton (1789), conserved against Damapana Adans. (1763), is conserved automatically against the earlier homonym Smithia Scop. (1777) – Blumea DC. (1833) is conserved automatically against Blumea Rchb. (1828–1829), although the latter name is not listed alongside the former in App. III.
- A name may be conserved in order to preserve a particular spelling or gender. A name so conserved is to be attributed without change of date to the author who validly published it, not to an author who later introduced the conserved spelling or gender.
- The spelling Rhodymenia, used by Montagne (1839), has been conserved against the original spelling Rhodomenia, used by Greville (1830). The name is to be cited as Rhodymenia Grev. (1830).
- The lists of conserved names will remain permanently open for additions and changes. Any proposal of an additional name must be accompanied by a detailed statement of the cases both for and against conservation. Such proposals must be submitted to the General Committee (see Div. III), which will refer them for examination to the committees for the various taxonomic groups (see also Art. 34.1 and 56.2).
- In the interest of nomenclatural stability, for organisms treated as fungi (including lichenicolous fungi, but excluding lichen-forming fungi and those fungi traditionally associated with them taxonomically, e.g. Mycocaliciaceae), lists of names may be submitted to the General Committee, which will refer them to the Nomenclature Committee for Fungi (see Div. III) for examination by subcommittees established by that Committee in consultation with the General Committee and appropriate international bodies. Accepted names on these lists, which become Appendices of the Code once reviewed and approved by the Nomenclature Committee for Fungi and the General Committee, are to be listed with their types together with those competing synonyms (including sanctioned names) against which they are treated as conserved (see also Art. 56.3).
- Entries of conserved names may not be deleted.
- Alternaria “Nees ex Wallr. (1833)” was conserved against Macrosporium Fr. (1832) in the Seattle Code (1972), as Fries’s name had been used in the then starting-point work for fungi. Following the abolition of later starting-point dates for fungi at the Sydney Congress in 1981 and in the Sydney Code (1983), and the recognition that Nees’s name had been accepted by Fries in the introduction to the sanctioning work (Syst. Mycol. 1: xlvi. 1821), conservation became unnecessary. As the entry cannot be deleted, Alternaria Nees (1816–1817) continues to be listed in App. III, but without a corresponding rejected name.
- The places of publication cited for conserved names of families in App. IIB are treated as correct in all circumstances and consequently are not to be changed, except under the provisions of Art. 14.12, even when otherwise such a name would not be validly published or when it is a later isonym.
- When a proposal for the conservation of a name has been approved by the General Committee after study by the Committee for the taxonomic group concerned, retention of that name is authorized subject to the decision of a later International Botanical Congress (see also Art. 34.2 and 56.4).
- When a proposal for the conservation of a name has been referred to the appropriate Committee for study, authors should follow existing usage of names as far as possible pending the General Committee’s recommendation on the proposal (see also Rec. 34A and 56A).
1 The International Code of Zoological Nomenclature and the International Code of Nomenclature of Bacteria use the terms “objective synonym” and “subjective synonym” for homotypic and heterotypic synonym, respectively.