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Essential ICN Rules (Madrid Code) to Know

Understanding the Core Principles of Botanical Nomenclature

Reference:

Turland, N.J., Wiersema, J.H., Barrie, F.R., Gandhi, K.N., Gravendyck, J., Greuter, W., Hawksworth, D.L., Herendeen, P.S., Klopper, R.R., Knapp, S., Kusber, W.-H., Li, D.-Z., May, T.W., Monro, A.M., Prado, J., Price, M.J., Smith, G.F. & Zamora Señoret, J.C. 2025. International Code of Nomenclature for algae, fungi, and plants (Madrid Code). Regnum Vegetabile 162. Chicago: University of Chicago Press.

https://www.iaptglobal.org/_functions/code/madrid

DEFINITION OF TERMS IN ICN (MADRID CODE)

Analysis: A figure or group of figures, often presented separately from the main illustration of the organism (though usually on the same page or plate), showing details aiding identification, with or without a separate caption (Art. 38.10; see also Art. 38.11).

Available name: A name published under the International Code of Zoological Nomenclature with a status equivalent to that of a validly published name under the International Code of Nomenclature for algae, fungi, and plants (Art. 45 Ex. 1 footnote).

Basionym: The legitimate, previously published name on which a new combination or name at new rank is based. The basionym does not itself have a basionym; it provides the final epithet, name, or stem of the new combination or name at new rank (Art. 6.10) (see also name at new rank, new combination).

Binding decision: A recommendation made by the General Committee and ratified by an International Botanical Congress on (1) whether or not a name is validly published (Art. 38.5) or (2) whether or not names are to be treated as homonyms (Art. 53.4) (see also Art. 20 Note 1). Binding decisions are listed in (1) App. VI or (2) App. VII.

Binomial (binary combination): A generic name combined with a specific epithet to form a species name (Art. 23.1) (see also combination).

Combination: A name of a taxon below the rank of genus, consisting of the name of a genus combined with one or two epithets (Art. 6.7).

Conserved name (nomen conservandum): (1) A name of a family, genus, or species, or in certain cases a name of a subdivision of a genus or of an infraspecific taxon, declared legitimate, even though it may have been illegitimate when published, and taking precedence over other specified names even if it lacks priority (Art. 14.1–14.7, 14.10, App. II, III, and IV). (2) A name for which the type, orthography, or gender has been determined by the conservation process (Art. 14.8, 14.9, 14.11, App. III, and IV) (see also protected name).

Conserved type (typus conservandus): A type attached to a name by the conservation process (Art. 14.8 and 14.9) to serve as the nomenclatural type when it would otherwise not be the type under Art. 7–10, 40, and F.5.4 (see also nomenclatural type).

Correct name: The name that must be adopted in accordance with the rules for a taxon with a particular circumscription, position, and rank (Art. 6.6, 11.1, 11.3, and 11.4)

Date of name: The date of valid publication of a name (Art. 33.1).

Description: A statement explicitly describing one or more features of an individual taxon. A description need not be diagnostic (Art. 38.4). It may include morphological, anatomical, biochemical, karyological, molecular, or similar features of the taxon but cannot serve as a validating description if it describes only properties such as those listed in Art. 38.3. Note that a description or a diagnosis is required for valid publication of a name of a new taxon (Art. 38.1(a)). A name, by itself, may convey some descriptive information about the taxon to which it is applied but is not sufficient to serve as a description or a diagnosis (see also diagnosis).

Descriptive name: A name of a taxon above the rank of family not formed from a generic name (Art. 16.1(b)).

Designation: [Not defined] – the term used for what appears to be a name but that (1) has not been validly published and hence is not a name in the sense of the Code (Art. 6.3) or (2) is not to be regarded as a name (Art. 20.4 and 23.7) (see also binary designation, type designation).

Diagnosis: A statement of properties that in the opinion of its author distinguishes a taxon from other taxa (Art. 38.2). Note that a diagnosis or a description is required for valid publication of a name of a new taxon (Art. 38.1(a)) (see also description).

Effective publication: Publication in accordance with Art. 29–31 (Art. 6.1).

Epithet: [Not defined] – used for the words in a combination other than the generic name and any rank-denoting term; hyphenated words are equivalent to a single word (Art. 6.7, 11.4, 21.1, 23.1, and 24.1; see also Art. H.10.2) (see also final epithet).

Figure: See analysis.

Final epithet: The last epithet in sequence in any particular combination, whether at the rank of a subdivision of a genus, or of a species, or of an infraspecific taxon (Art. 6.10 footnote).

Fossil-taxon: A taxon (diatom taxa excepted) the name of which is based on a fossil type (Art. 1.2 and 13.3).

Gathering: Material collected by the same collector(s) at the same time from a single locality and presumed to be of a single taxon (Art. 8.2 footnote; see also Art. 8 Note 1) (see also duplicate).

Holotype: The one specimen or illustration designated in the protologue as the nomenclatural type of a name of a new species or infraspecific taxon or, when no type was designated, used by the author(s) when preparing the protologue (Art. 9.1, 9.2, and Note 1) (see also nomenclatural type).

Homonym: A name spelled exactly like another name published for a taxon at the same rank based on a different type (Art. 53.1). Note that names of subdivisions of the same genus or of infraspecific taxa within the same species that are based on different types and have the same final epithet are homonyms, even if they differ in rank (Art. 53.3), because the rank-denoting term is not part of the name (Art. 21 Note 1 and Art. 24 Note 2) (see also confusingly similar names).

Illegitimate name: A validly published name that is not in accordance with specified rules (Art. 6.4), principally those on superfluity (Art. 52) and homonymy (Art. 53 and 54) (see also homonym, superfluous name).

Illustration: A work of art or a photograph depicting a feature or features of a species or infraspecific taxon, e.g. a drawing, a picture of a herbarium specimen, or a scanning or transmission electron micrograph, but not a photograph of habitat (Art. 6.1 footnote).

Improper Latin termination: A termination of a name or epithet not in accordance with the termination required by the Code (Art. 16.3, 18.4, 19.7, and 32.2).

Indelible autograph: Handwritten material reproduced by some mechanical or graphic process (such as lithography, offset, or metallic etching) (Art. 30.6).

Indirect reference. A clear (if cryptic) indication, by an author citation or in some other way, that a previously and effectively published description or diagnosis applies (Art. 38.15) or that a basionym or replaced synonym exists (Art. 41.3).

Lectotype: One specimen or illustration designated from the original material as the nomenclatural type, in conformity with Art. 9.11 and 9.12, if the name was published without a holotype, or if the holotype is lost or destroyed, or if a type is found to belong to more than one taxon (Art. 9.3) (see also nomenclatural type).

Legitimate name: A validly published name that is in accordance with the rules, i.e. one that is not illegitimate (Art. 6.5) (see also illegitimate name).

Monotypic genus. A genus for which a single binomial is validly published (Art. 38.7).

Name: A name that has been validly published, whether it is legitimate or illegitimate (Art. 6.3) (see also designation).

Neotype: A specimen or illustration selected to serve as the nomenclatural type if no original material exists or as long as it is missing (Art. 9.8 and 9.13; see also Art. 9.16 and 9.19) (see also nomenclatural type).

Nomen conservandum (nom. cons.): See conserved name.

Nomen novum (nom. nov.): See replacement name.

Nomen nudum (nom. nud.): A designation of a new taxon published without a description or diagnosis or reference to a description or diagnosis (Art. 38 Ex. 1, Rec. 50B) (see description, designation, diagnosis).

Nomen rejiciendum (nom. rej.): A name rejected in favour of a name conserved under Art. 14 or a name ruled as rejected under Art. 56 (App. IIA, III, IV, and V) (see also nomen utique rejiciendum, rejected name).

Nomen sanctionatum (nom. sanct.): See sanctioned name.

Nomenclatural type: A specimen, or in some cases an illustration (Art. 8.1), to which the name of a taxon is permanently attached (Art. 7.2). The nomenclatural type of the name of a species or infraspecific taxon is a holotype (Art. 9.1), lectotype (Art. 9.3), neotype (Art. 9.8), or conserved type (Art. 14.9), any of which may be supported by an epitype (Art. 9.9).

Non-fossil taxon. A taxon the name of which is based on a non-fossil type (Art. 13.3).

Nothogenus: A hybrid genus (Art. 3.2).

Original material: The set of specimens and illustrations from which a lectotype may be chosen (see Art. 9.4, Art. 9 Notes 2–5, Art. F.3.10, and Art. F.3 Note 2 for details), or the holotype (see Art. 9.1).

Page reference: Citation of the page or pages on which the basionym or replaced synonym was validly published or on which the protologue appears (Art. 41 Note 1; see also Art. 41 Note 2 and Rec. 41A.2).

Paratype: Any specimen cited in the protologue that is neither the holotype nor an isotype, nor one of the syntypes if in the protologue two or more specimens were simultaneously designated as types (Art. 9.7).

Priority: A right to precedence established by the date of valid publication of a legitimate name (Art. 11) or of an earlier homonym (Art. 53 Note 4), or by the date of designation of a type (Art. 7.10, 7.11, and F.5.4).

Pro synonymo (pro syn., as synonym): A citation indicating that a name or a designation is merely cited as a synonym (Art. 36.1(b) and Rec. 50A) (see designation).

Protected name: The name of an organism treated as a fungus listed (in App. IIA, III, or IV) with its type and treated as conserved against any competing listed or unlisted synonyms or homonyms (including sanctioned names), although conservation under Art. 14 overrides this protection (Art. F.2.1) (see also conserved name).

Protologue: Everything associated with a name at its valid publication, e.g. description, diagnosis, illustrations, photographs of habitat, references, synonymy, geographical data, citation of specimens, discussion, and comments (Art. 6.13 footnote).

Provisional name: A designation proposed in anticipation of the future acceptance of the taxon concerned, or of a particular circumscription, position, or rank of the taxon (Art. 36.1(a)) (see designation).

Rank: [Not defined] – used for the relative position of a taxon in the taxonomic hierarchy (Art. 2.1). For suprageneric names published on or after 1 January 1887, the rank is indicated by the termination of the name (see Art. 37.2 and footnote). For names published on or after 1 January 1953, a clear indication of the rank is required for valid publication (Art. 37.1).

Rejected name: A name ruled as not to be used, either by formal action under Art. 14, 56, or F.7 overriding other provisions of the Code (see nomen rejiciendum, nomen utique rejiciendum) or because it was nomenclaturally superfluous when published (Art. 52) or a later homonym (Art. 53 and 54). A name treated as rejected under Art. F.7 may become eligible for use by conservation under Art. 14.

Replaced synonym: The legitimate or illegitimate, previously published name on which a replacement name (nomen novum) is based. The replaced synonym, when legitimate, does not provide the final epithet, name, or stem of the replacement name (Art. 6.11) (see replacement name).

Replacement name (nomen novum): A new name published as an explicit substitute (avowed substitute) for a legitimate or illegitimate, previously published name, which is its replaced synonym and which, when legitimate, does not provide the final epithet, name, or stem of the replacement name (Art. 6.11 and 7.4; for names not explicitly proposed as substitutes see Art. 6.12 and 6.13) (see replaced synonym).

Sanctioned name (nomen sanctionatum): The name of a fungus treated as if conserved against earlier homonyms and competing synonyms, through acceptance in a sanctioning work (Art. F.3.1).

Specimen: A gathering, or part of a gathering, of a single species or infraspecific taxon, disregarding admixtures, mounted either as a single preparation or as more than one preparation with the parts clearly labelled as being part of the same specimen or having a single, original label in common (Art. 8.2 and 8.3; for fossil-taxa see Art. 8.6). A specimen may not be a living organism or an active culture (Art. 8.4) (see gathering).

Subdivision of a family: Any taxon at a rank between and not including family and genus (Art. 4 Note 2).

Subdivision of a genus: Any taxon at a rank between and not including genus and species (Art. 4 Note 2).

Superfluous name: A name that, when published, was applied to a taxon that, as circumscribed by its author, definitely included the type of a name that ought to have been adopted, or of which the epithet ought to have been adopted, under the rules (Art. 52.1). A superfluous name is illegitimate except as provided by Art. 52.4 or unless conserved (Art. 14), protected (Art. F.2), or sanctioned (Art. F.3).superseded. [Not defined] – used for a designation of a type that is not followed but is replaced by a subsequent designation of a different type under the provisions of Art. 9.15, 9.18, 9.19, 10.2, or 10.5.

Synonym: [Not defined] – one of two or more names that apply to the same taxon. Also used in the sense of a name that applies to a taxon but is not the correct name for that taxon (see heterotypic synonym, homotypic synonym).

Syntype: Any specimen cited in the protologue when there is no holotype, or any of two or more specimens simultaneously designated in the protologue as types (Art. 9.6). Illustrations cannot be syntypes.

Tautonym: A binary designation in which the specific epithet exactly repeats the generic name (Art. 23.4).

Taxon (taxa): A taxonomic group at any rank (Art. 1.1).

Validly published: Effectively published and in accordance with the relevant provisions of Art. 32–45, F.4, F.5.2, F.5.3, and H.9 (Art. 6.2) (see designation, name; see also effective publication).

Ponticulifora

Article 51.1. Legitimate Name

A legitimate name must not be rejected merely because it, or its epithet, is inappropriate or disagreeable, or because another is preferable or better known (but see Art. 14, 56.1, and F.7.1), or because it has lost its original meaning.

Example:

Watznaueria angustoralis Reinhardt, 1964 not be rejected in favour of invalid but better known Tremalithus barnesiae Black, 1959 [Invalid ICN, Art. 35.1]

Z sileensis 1

Article 6.4. Illegitimate Name

An illegitimate name is one that is designated as such in Art. 18.3, 19.6, 52–54, F.3.3, or F.6.1(see also Art. 21 Note 1 and Art. 24 Note 2). A name that according to this Code was illegitimate when published can become legitimate later only if:

(a) it is conserved (Art. 14), protected (Art. F.2), or sanctioned (Art. F.3); or

(b) the name is nomenclaturally superfluous under Art. 52 and its intended basionym is conserved or protected; or

(c) Art. 18.3 or 19.6 so provide.

T pulcher

Article 11.2. Priority

A name has no priority outside the rank in which it is published (but see Art. 53.4).

Example:

Species Cyclococcolithus astroporus Stradner, 1963 has priority over the subspecies Cyclococcolithus leptoporus inversus Deflandre in Deflandre &Fert, 1954

Species Helicosphaera truncata Bramlette & Wilcoxon, 1967 has priority over the subspecies Helicosphaera seminulum recta Haq, 1966 [if considered synonyms]

Because Cyclococcolithus astroporus and Helicosphaera truncata were published before the above subspecies were amended into species ranks

Syracosphaera pulchra 1473 5

Article 12.1. Status

A name of a taxon has no status under this Code unless it is validly published (see Art. 6.3, but see Art. 14.4 and 14.9).

If the species is invalid when published can not be amended because the invalid species has no statute under ICN.

Loeblich & Tappan (1966) states, "According to ICZN, an available name satisfies the rule; the valid name of a taxon is the oldest available name applied to it. The equivalent terms in the ICBN (=ICN) are legitimate and correct, respectively."

Discoaster brouweri 1466 11


Article 9.1. Holotype
A holotype of a name of a species or infraspecific taxon is the one specimen or illustration (but see Art. 40.6) either:

(a) designated in the protologue as the nomenclatural type; or

(b) used by the author(s) in preparing the protologue when no type was designated; or

(c) as described in Art. 9 Note 1.

As long as the holotype exists, it fixes the application of the name concerned (but see Art 9.15).

Holococcolith pon 1473 15



Article 40.1. Type

Publication on or after 1 January 1958 of the name of a new taxon of the rank of genus or below is valid only when the type of the name is indicated (see Art. 7-10; but see Art. H9 Note 1for the names of certain hybrids).

C dela web




Article 35.1. Assignment

A name of a taxon below the rank of genus is not validly published unless the name of the genus or species to which it is assigned is validly published at the same time or was validly published previously (but see Art. 13.4).

D kuepperi 4

Article 9.3. Lectotype

A lectotype is one specimen or illustration designated from the original material (Art. 9.4) as the nomenclatural type, in conformity with Art. 9.11 and 9.12:

(a) if the name was published without a holotype; or(

b) if the holotype is lost or destroyed; or

(c) if a type is found to belong to more than one taxon (see also Art. 9.14).

For sanctioned names (Art. F.3), a lectotype may be selected from among elements associated with either or both the protologue and the sanctioning treatment (Art. F.3.10).

________

Conditions for the designation of lectotype can be summarised as below:

1. illustration from the original material as the nomenclatural type

Only original slide or sample is acceptable for "original material". The type area or the type section can not be satisfactory for "original material" designation. They may contain multiple stratigraphic levels / different nannofossil assemblages.

2. if no holotype was indicated at the time of publication

The lectotype can only be designated for the species published before 1 January 1958 if no holotype was indicated at the original publication.

After 1 January 1958, if no holotype was indicated at the original publication, that species is invalid and has no place in ICN (Art. 12.1).

Example: Cribrosphaerella danica Brotzen, 1959

3. if the holotype is missing

This is not applicable for nannofossils because the holotypes photos of all the nannofossils published are publicly available.

4. if a type is found to belong to more than one taxon

This is the only genuine reason for the designation of a lectotype for post 1 January 1958 publications.

Tenebrislaminam lordii 1466 2

LATIN TERMS AND THEIR ABBREVIATIONS USED IN THE MADRID CODE

This list includes Latin terms and their abbreviations, either or both of which appear in this Code, except for Latin words abbreviated as part of book or journal titles in bibliographic citations. Terms in bold have entries in the Glossary.

TermAbbreviationMeaning
ad interimad int.for the time being
AnonymusAnon.Anonymous
auctorumauct.of the authors
clarus / clarissimuscl.famous / most famous
combinatio novacomb. nov.new combination
confercf.compare
descriptio generico-specifica–description of genus and species, i.e. one description simultaneously validating the name of a genus and the name of its single species
emendavitemend.(he / she) has emended
epitypus–epitype
et aliiet al. / & al.and others
et ceteraetc.and the others (remainder, rest)
ex / e–from
ex holotypo–ex-holotype
ex isotypo–ex-isotype
ex typo–ex-type
exclusa specie / exclusis speciebusexcl. sp.excluding the species (singular) / excluding the species (plural)
exclusa varietate / exclusis varietatibusexcl. var.excluding the variety / excluding the varieties
excluso genere / exclusis generibusexcl. gen.excluding the genus / excluding the genera
exempli gratiae.g.for example
filiusf.son (in author citations)
forma specialis / formae specialesf. sp.special form / special forms
genus novumgen. nov.new genus
hic designatus–designated here
holotypus–holotype
HortulanorumHort.of gardeners (in citations of scientific names; could also refer to hortus, garden)
iconic.image, i.e. an illustration
id esti.e.that is
in litterisin litt.in writing
incertae sedis–of an uncertain seat, i.e. of uncertain taxonomic position
ineditusined.not published
lectotypus–lectotype
loco citatol.c. / loc. cit.in the place cited
manuscriptum / manuscriptams. / mss.manuscript / manuscripts
mihim.for me, used after a scientific name to indicate that the author has introduced it
mutatis characteribusmut. char.with changed features (characters)
nec–and not, nor
neotypus–neotype
nobisnob.for us, used in the same way as mihi
nomen alternativumnom. alt.alternative name, for eight specified family names and one subfamily name
nomen conservandumnom. cons.name to be conserved, i.e. conserved name
nomen novumnom. nov.new name, i.e. a replacement name
nomen nudumnom. nud.naked name, i.e. without a validating description or diagnosis or reference to one
nomen rejiciendumnom. rej.name to be rejected, i.e. rejected name
nomen sanctionatumnom. sanct.sanctioned name
nomen specificum legitimum–legitimate specific name, i.e. Linnaean phrase name
nomen triviale / nomina trivialia–trivial name, i.e. Linnaean specific epithet / trivial names
nomen utique rejiciendumnom. utique rej.name to be rejected outright (suppressed name)
non–not
opera utique oppressa–suppressed works
opere citatoop. cit.in the work cited
orthographia conservandaorth. cons.orthography to be conserved (see orthographical variants)
pro hybridapro hybr.as a hybrid
pro partep. p.in part
pro speciepro sp.as a species
pro synonymopro syn.as a synonym
sensu amplos. ampl.in a large (ample) sense
sensu latos. l.in a broad (wide) sense
sensu strictos. str.in a narrow (strict) sense
species novasp. nov.new species
status novusstat. nov.new status, i.e. name at new rank
tabulat.tablet, i.e. plate (illustration)
typus–type, i.e. nomenclatural type
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