Nomenclatural FAQs

This FAQ (Frequently Asked Questions) document is designed to help phycological authors avoid common errors in frequently used nomenclatural procedures. For more information and questions not covered here, please consult a nomenclatural expert or the current on-line version of The International Code of Nomenclature for algae, fungi and plants (ICN).

The ICN is a set of rules and recommendations that govern the scientific naming of all organisms traditionally treated as algae, fungi, or plants, whether fossil or non-fossil, including blue-green algae (Cyanobacteria), chytrids, oomycetes, slime moulds, and photosynthetic protists with their taxonomically related non-photosynthetic groups (but excluding [the genus] Microsporidia). Before 2011 it was called the International Code of Botanical Nomenclature (ICBN).

The current version of the ICN (Shenzhen Code) was published in July 2018 and can be purchased here. Changes approved (and not approved) by the XIXth International Botanical Congress are to be found at Taxon, Volume 66, Number 1, February 2017, pp. 217-274.

The present FAQ guide is provided with the caveat that the printed ICN is the definitive source of nomenclatural rules for algae (including Cyanobacteria) and that - like all regulatory instruments - it is open to interpretation. Expert advice is always helpful, but can be difficult to obtain.

 

Guía en español de Guiry & Pedroche (2022) (Descargar PDF).

 

Please note a major change that dates from the Melbourne Code (see McNeill & Turland, 2011):

"The second change to the Code approved in Melbourne to take effect from 1 January 2012 is that the description or diagnosis required for valid publication of the name of a new taxon of all organisms falling under the Code may be in either English or Latin. This is the current provision for names of plant fossils, but all new non-fossil taxa have required a Latin description or diagnosis (fungi and plants from 1 January 1935; algae (including cyanobacteria, if treated under the Code) from 1 January 1958). This has no bearing on the form of scientific names, which continue to be Latin or treated as Latin. Individual journal requirements for Latin and/or English will, of course, be determined by the editors of those journals."

Frequently Asked Questions

• How do I describe new taxa at the rank of species and below?
• How do I describe new taxa at the rank of genus and above?
• What is an ex-type?
• How and when do I designate a lectotype for a species?
• How and when do I designate a neotype for a species?
• How and when do I designate an epitype for a species?
• How do I validly publish new combinations?
• How do I validly publish a replacement name (a nomen novum)?
• How do I correctly give author citations for taxa?
• What is a basionym?
• What is a Starting Point?
• Which are the most common epithets used for new species?
  
  

Abbreviations

sp. nov. = species nova [not "novum"], new species

gen. nov. = genus novum [not "nova" or "novus"], new genus

fam. nov. = familia nova [not "novum"], new family (-aceae)

ord. nov. = ordo novus [not "nova"], new order (-ales)

classis nov. = classis nova [not "novis"] (-phyceae)

comb. nov. = combinatio nova, new combination

stat. nov. = status novus, name at a new rank

var. nov. = varietas nova, new variety

f. nov. = forma nova, new forma

1. New species or infraspecies

In order to describe a new taxon validly so that the name meets the requirements of the International Code of Nomenclature for algae fungi and plants (ICN), it must meet certain requirements below for validity (a-e, below).

a. Publish effectively

A name is not valid unless it is effectively published. Effective publication is currently achieved in two ways: the distribution of printed matter (through sale, exchange, or gift) to the general public or to scientific institutions with generally accessible libraries; or, after 1 January 2012, through the distribution of PDFs with an International Standard Serial Number (ISSN) or an International Standard Book Number (ISBN) (Art. 29.1). So papers published in Notulae Algarum meet the requirements for effective publication as they are in PDF format and have an ISSN number. Abstract booklets distributed at meetings and not deposited in a library do not. CDs and DVDs do not. Word documents used as "Supplementary Materials" do not (but PDFs do provided the journal has an ISSN number.

b. Conform with Arts 16–27

A name is not valid unless it conferms with ICN Articles 16-27 as follows:

• The name must be in Latin (or is acceptably Latinized); however, there is an extraordinary range of options open to the prospective author.
• Construct the name according to ICN Art. 23 and Art. 60. Make sure that the epithet conforms with recommendations and conventions if dedicating the name to a person, a place, or referring to growth on a substratum or host. Pay special attention to gender of generic names (see Art. 62.2 for some fixed genders for compound generic names), which are often provided in AlgaeBase, and the corresponding adjectival species epithets. However, this does not apply to epithets that are nouns—these retain their own gender and do not change their endings (e.g. Alexandrium catenella, not Alexandrium "catenellum"). A common error in naming a species after a female person is to use "-ii", as personification for a female is "-iae". For people whose names end in "a" (e.g., Kintaro Okamura) an "e" is added ("okamurae"). Epithets ending in "-cola" are not declinable (Art. 23). We provide a key to help with the formation of honorific epithets here.
• A tautonym is invalid: the genus name and the species epithet may not be exactly the same (e.g., Lutra lutra the European Otter), even though this is permitted in the Zoological Code, such a name would be invalid under the ICN. However, a name such as "Ceramium ceramoides" would be valid as it does not exactly repeat the genus name.
  
  

c. Description or diagnosis

• Provide a description or diagnosis (or both) for your taxon or give a full and direct reference to a previously published description or diagnosis uniquely applicable to your alga. From January 1, 2012, for valid publication an English or Latin diagnosis or description must be provided. A diagnosis or description in any other language is currently not acceptable.
• You may use a single combined description or diagnosis (i.e. a descriptio generico-specifica) for both a new genus and a new species if there is a single species in the new genus and both are new.
• Some diatomists have developed the habit of providing a full description and a differential diagnosis, which is very hepful but not required for validity.
  
  

d. Designate a type

• Designate a type (authors must use the word "typus","type", "holotypus" or "holotype," and cite the single herbarium or place the specimen is housed). See Index Herbariorum for approved institutional acronyms. You do not have to say "here designated" for a type (only a lectotype, epitype or neotype).
• Designate a single collection made at one place and time represented as a single specimen (or admixture for microalgae) in a single institute (list the collector, date, and collection number);
• Or designate a permanently metabolically inactive culture or tissue [e.g. frozen, dried, or pickled] designated by a unique reference and in a single institute (one should write "preserved in a permanently inactive state" or a similar phrase to ensure that readers know the type is not a living culture or one that is in a temporarily inactive state).
• Or designate an effectively published illustration (concurrently or previously published) if and only if there are technical difficulties preserving a collection of a microalga. If previously published, a full and direct reference to the place of prior publication is required.
• Do not indicate that the "type" is in more than one physical location. Duplicates of the type collection are isotypes when deposited elsewhere or are otherwise separate from the type.
• Cultures derived from the holotype, or used to generate the holotype are not themselves types. Because preserved cultures can serve as 'type,' do not indiscriminately cite both a specimen and a culture as type. Ensure one is specifically designated as holotype and specifically state where that single type is located. Otherwise the name will be invalid.
  

 

e. Alternative names and expressing doubt

• Do not provide alternative Latin names for the same taxon. Otherwise all names will be invalid (Art. 36.2).
• Do not suggest that your new scientific name is tentative, provisional, a temporary fix, or express any other doubt about accepting a name for a new taxon, including the inclusion of a question mark. Otherwise you may may render itinvalid.
  

 

f. Provide an illustration

• In order to be valid a non-fossil alga must, in accordance with Art. 44.2 be provided with an illustration: "In order to be validly published, a name of a new taxon of non-fossil algae of specific or lower rank published on or after 1 January 1958 must be accompanied by an illustration or figure showing the distinctive morphological features, ...or by a reference to a previously and effectively published illustration or figure. Recommendation 44A.1 is that the illustration or figure should be prepared from actual specimens, preferably including the type.
  
  

e. Be legitimate

• While this is not required for validity, a name spelled exactly like an earlier valid name (regardless of whether this name is legitimate or illegitimate), or confusingly closely spelled is illegitimate. Homonyms in use in other Codes are not necessarily illegitimate but should be avoided.
  
  

Example:

Rhodophyllis imbricata J.J.Smith, sp. nov. (Figs 1-10)
Diagnosis: From other species of the genus differing in the imbricate leaves and marginal cystocarps.
Type: USA: Alaska: Anchorage (61.2181° N, 149.9003° W), 12 m depth, 07.ii.1910, coll. J.J. Smith No. 22213 (US 1234567; Fig. 1).
Etymology: from the Latin imbricatus, -a, -um (adj.) , having adjacent edges ovelapping.

Remember: an invalid name can be validated, but an illegitimate name cannot be legitimised, except by nomenclatural conservation.

2.How do I describe new taxa at the rank of genus and above?

Conform generally with the stipulations above for species and below.

Construct the name according to ICN Art. 20 and 60. Follow Recommendation 20A(h) and 60B when dedicating the name of the genus to a person. Check databases (see above) to make sure the generic name has not been used previously.

You must not coin a genus name that concides with a tern used in morphology (e.g. Parvulus, -a, -um, Lanceolatus, -a, -um, Pulvinatus, -a, -um). However, a compund like Chloroparvula is acceptable. A genus name must be one word or two words joined by a hyphen, but is better to avoid hyphenated generic names.

Otherwise a name may be taken from any source whatever, and may even be composed in an absolutely arbitrary manner, but it must not end in -virus.

Examples: Cafeteria (presumably coined whilst eating); Bangia (named for Neils Hofman-Bang (1776-1855), a Danish botanist and not for any explosive sound; Cabra ("Place where small organisms live" (from the language of the Eora, an indigenous people of Botany Bay, but also in Irish An Chabrach, meaning "poor land", anglicized to Cabra, an area of north Dublin).

A diagnosis or description must be supplied when describing a new genus or any other taxon.

Designate the type of the genus by citing the name of one previously or concurrently, validly published species. Use the word "typus" or "type."

Examples

Rhodymeniopsis J.J.Smith, gen. nov.
Diagnosis: Similar to the genus Rhodymenia but differing in the development of tetrasporangia and cystocarps on the underside of peltate surface proliferations.
Type: Rhodymeniopsis antarctica J.J. Smith

Rhodymeniopsidaceae J.J.Smith, fam. nov.
Diagnosis: Similar to the family Rhodymeniaceae but differing in the development 6-celled carpogonial branched and tetrasporangia with tetrahedrally arranged spores.
Type: Rhodymeniopsis antarctica J.J.Smith

Rhodymeniopsidales J.J.Smith, ord. nov.
Diagnosis: Similar to the order Rhodymeniaceae but differing in the development 6-celled carpogonial branched and tetrasporangia with tetrahedrally arranged spores.
Type: Rhodymeniopsis antarctica J.J.Smith

Rhodymeniopsidophyceae J.J.Smith, cl. nov.
Diagnosis: Similar to the order Florideophyceae but differing in the development of 6-celled carpogonial branched and tetrasporangia with tetrahedrally arranged spores.
Type: Rhodymeniopsis antarctica J.J.Smith

3. What is an ex-type?

A living culture of algae or fungi permanently preserved in a metabolically inactive state obtained from a type may be referred to as an ex-type (See ICN Art. 8, Recommendation 8.B2 for more information) or a "representative strain". It is linked to the type, but it is not the same as the type. Depending on the nature of the type, it may be called an ex-holotype, ex-neotype, ex-epitype, etc. Such cultures, as well as the place where the living culture is preserved, should be indicated in publications, especially for new taxa. This information is often listed next to the type designation.

Example

Chlorella arboricola P.M.Smith, sp. nov.
Diagnosis: From other species of the genus differing in its thick cell walls with spiny outgrowths.
Typus: USA: Idaho, Valley Co., near McCall, on the bark of Pinus sp., 07.vii.1912, coll. P.M. Smith, Smith 22 (NY); ex-type: UTEX 7493.

4. How and when do I designate a lectotype for a species?

A lectotype is designated when there was no holotype in the original description or if it has been lost or destroyed. Rarely, a lectotype may be designated when the holotype belongs to more than one taxon (see ICN Art. 9 for more information).

A lectotype is a designated specimen or illustration that is part of the original material (protologue). Simply speaking, original material consists of specimens and published or unpublished illustrations that were definitely used in the original description of a name.

When designating a lectotype, priority must be given to the following types of materials in the order given below (see ICN Art. 9.12):

1. Isotype (for a definition see ICN Art. 9.3)
2. Syntype (also possibly an isosyntype) (for a definition see ICN Art. 9.4)
3. Paratype (for a definition see ICN Art. 9.5)
4. Uncited specimen, uncited illustration, cited illustration

On or after 1 January 1990, the herbarium housing the specimen or unpublished illustration must be cited and the term "lectotypus" or "lectotype" must be given along with the phrase "hic designatus" or "designated here." A full and direct reference to the place of publication of previously published illustrations should be given, and it is ideal if the illustration can be reproduced in the current work. Lectotypification is only achieved through effective publication, not merely by the annotation of specimens in a collection. In the case of accepted names based on a basionym or replaced synonym, the basionym or replaced synonym should be the name that is lectotypified.

Example

Pseudophyllophora baltica (Peck) Peck, Phycologia 3: 377. 1965.
Basionym: Phyllophora baltica Peck, Phycologia 1: 100. 1963. Lectotype of Phyllophora baltica (here designated): Sweden: Gothenburg, coll. Peck, Peck 1239 (BM).

5. How and when do I designate a neotype for a species?

A neotype is designated when no original material (specimens and published or unpublished illustrations that were definitely used in the original description of a name) exists. With rare exceptions, a lectotype designated from original material supersedes a neotype. Thus, it is important to not overlook any original material when considering neotype designation.

A neotype is a specimen or illustration, preferably the former. Special consideration should be given so that the designated neotype matches the material described in the protologue as closely as possible.

On or after 1 January 1990, the herbarium housing the specimen or unpublished illustration must be cited and the term "neotypus" or "neotype" must be given along with the phrase "hic designatus" or "designated here." Neotypification is only achieved through effective publication. In the case of accepted names based on a basionym or replaced synonym, the basionym or replaced synonym should be the name that is neotypified.

Example (not intended for valid publication):

Schottera nyssae (Peck) Peck, Phycologia 3: 9. 1965.
Basionym: Phyllophora nyssae Peck, Phycologia 2: 39. 1964.

Neotypus of Phyllophora nyssae (here designated): USA: California, near Eureka, in pools, 10.vii.2001, coll. J.D. Smith, Smith 2211 (UC).

6. How and when can I designate an epitype for a species?

An epitype is designated when the existing nomenclatural type (holotype, lectotype, or neotype) or all the original material is insufficient to allow for precise application of a name. An epitype may be a specimen or illustration, but a specimen should nearly always be employed. Only one epitype is allowed per name. So, it must be carefully chosen and authors should ensure that the epitype represents the same taxon as the type it supports.

For an epitypification to be effected, the herbarium housing the specimen or unpublished illustration must be cited or in the case of a published illustration, a full and direct bibliographic reference must be given; and on or after 1 January 1990, the term "epitypus" or "epitype" must be given along with the phrase "hic designatus" or "designated here." Additionally, the nomenclatural type (holotype, lectotype, or neotype) that the epitype supports must be explicitly cited. Epitypification is only achieved through effective publication. In the case of accepted names based on a basionym or replaced synonym, the basionym or replaced synonym should be the name that is epitypified.

Example

Neosiphonia nyssae (Peck) Peck, Phycologia 5: 9. 1913.
≡ Polysiphonia nyssae Peck, Phycologia 2: 39. 1910.
Neotypus of Polysiphonia nyssae (designated by M.J.Wynne, Phycotaxon 1: 54. 2012): USA: Maine, near Rockland, on Palmaria palmata, 10.vii.2001, coll. C.W. Schneider, Schneider 2211 (MICH).
Epitypus of Polysiphonia nyssae (here designated) USA: Rockland, Maine, 10.viii.2007, coll. Beethoven, ASM 55891 (UC).
Notes: The preservation in chemicals of the type prevents PCR amplification. Here, we designate a supporting epitype that is associated with DNA sequence data.

7. How do I publish new combinations validly?

The rules for publishing new combinations are covered in large part and in more detail in ICN Art. 38. The basionym must be cited with a clear and direct reference to its place of valid publication. For this, authors making new combinations must include journal and volume or book title, the page where protologue begins (be sure not to cite the entire pagination of the whole publication that includes the protologue), and date. Authors should make sure that adjectival species epithets agree grammatically with the genus in making new combinations (e.g. Fucus hibernicus becomes Agarum hibernicum and not Agarum hibernicus or Agarum hibernica), but such an error would invalidate a name.

Examples

Halichrysis imbricata (Peck) E.G.Smith, comb. nov.
Basionym: Rhodymenia imbricata Peck, Phycologia 3: 375. 1965.
Homotypic synonym: Chrysymenia imbricata (Peck) M.J.Wynne, Journal of Phycology, 55: 22. 2008.

Ulva cylindrica (Ellis) A.H.Smith, comb. & stat. nov.
≡ Enteromorpha erecta var. cylindrica Ellis, Phycologia 3: 376. 1965 (basionym).

In the latter example, the new combination also changes the rank from variety to species.

Please note: not citing the exact page may invalidate a new combination, which would require subsequent validation. Note in particular ICN Art. 41 Note 1: "For the purpose of Art. 41.5, a page reference (for publications with a consecutive pagination) is a reference to the page or pages on which the basionym or replaced synonym was validly published or on which the protologue appears, but not to the pagination of the whole publication unless it is coextensive with that of the protologue (see also Art. 30 Note 2)."

8. How do I validly publish a replacement name (a nomen novum or new name)?

Replacement names (ICN Art. 41) are similar to new combinations, but they are made in cases where there is an illegitimate later homonym or when the epithet of the basionym is already occupied in the genus where a new combination is required. The replaced synonym (strictly speaking it is not a basionym since the epithet is not being employed in the new name) must be cited with a clear and direct reference to its place of valid publication. For this, authors making replacement names must include journal and volume or book title, page where protologue begins (be sure not to cite the entire pagination of the whole publication that includes the protologue), and date. Authors should make sure that species epithets agree grammatically with the genus of their new name. It is also suggested that authors include a citation including a full and direct reference for the earlier homonym or species name already occupying a genus that necessitates the replacement name.

9. How do I correctly cite authorities for taxa?

Complete details about author citations (also know as "authorities") for taxa are found in ICN Arts. 46-50. For existing algal names, author citations may generally be found in Index Nominum Algarum and AlgaeBase, and authors' details can be found in IPNI (International Plant Names Index). For detailed taxonomic studies, authors should endeavour to verify that these databases are correct since they are not complete and are works in progress. Both of these sources spellout authors' surnames in full and where author abbreviations are required, the standards established by IPNI should be followed.

For new names including new combinations, authors should include author citations for such taxa. These author citations are not necessarily the same as the authorship for the whole publication. In cases where a standardized abbreviation does not yet exist, authors should try to conform to IPNI practices. Authors should be linked by the use of an "&" (ampersand, the equivalent of "et"), and the serial comma is not employed (viz., A, B & C not A, B, & C).

Example

Rhodymenia erythrophylla T.C.Saunders, H.Y.Hu & Spatafora, sp. nov.

10. What is a basionym?

According to the ICN a basionym is "a previously published legitimate name-bringing or epithet-bringing synonym from which a new name is formed for a taxon of different rank or position" (Art. 33.4, 49.1 and 52.3). It should be noted that a basionym does not really exist until it is used as the basis for a new name.

So, for example, the basionym for the name Rhodymenia pseudopalmata (J.V.Lamouroux) P.C.Silva is Fucus pseudopalmatus J.V.Lamouroux.

However, the name Guiryella repens Huisman & Kraft, for example, which has never been combined into another genus, is not a basionym because it has never been recombined. It would, of course, become a basionym if it were combined into another genus.

In making new combinations there is a very precise way in which the place and publication of the basionym must be cited (see No. 7 above).

11. What is a Starting Point?

The starting point for the nomenclature of algae is set by the Code as 1 May 1753 (Linnaeus, Species plantarum, ed. 1), except for filamentous Cyanobacteria, Desmids and the Oedogoniaceae which have a Later Starting Point as specified by the Code:

NOSTOCACEAE HOMOCYSTEAE, 1 January 1892 (Gomont, "Monographie des Oscillariées", in Ann. Sci. Nat., Bot., ser. 7, 15: 263-368; 16: 91-264). The two parts of Gomont's "Monographie", which appeared in 1892 and 1893, respectively, are treated as having been published simultaneously on 1 January 1892.
NOSTOCACEAE HETEROCYSTEAE, 1 January 1886 (Bornet & Flahault, "Révision des Nostocacées hétérocystées", in Ann. Sci. Nat., Bot., ser. 7, 3: 323-381; 4: 103-373; 5: 51-129; 7: 177-262). The four parts of the "Révision", which appeared in 1886, 1886, 1887, and 1888, respectively, are treated as having been published simultaneously on 1 January 1886.
DESMIDIACEAE (s. l.), 1 January 1848 (Ralfs, British Desmidieae).
OEDOGONIACEAE, 1 January 1900 (Hirn, "Monographie und Iconographie der Oedogoniaceen", in Acta Soc. Sci. Fenn. 27(1)).