Binomial nomenclature explained

In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomial name (which may be shortened to just "binomial"), a binomen, name, or a scientific name; more informally it is also historically called a Latin name. In the International Code of Zoological Nomenclature (ICZN), the system is also called nomenclature, with an "n" before the "al" in "binominal", which is a typographic error, meaning "two-name naming system".

The first part of the name – the generic name – identifies the genus to which the species belongs, whereas the second part – the specific name or specific epithet – distinguishes the species within the genus. For example, modern humans belong to the genus Homo and within this genus to the species Homo sapiens. Tyrannosaurus rex is likely the most widely known binomial.[1] The formal introduction of this system of naming species is credited to Carl Linnaeus, effectively beginning with his work Species Plantarum in 1753. But as early as 1622, Gaspard Bauhin introduced in his book Pinax theatri botanici (English, Illustrated exposition of plants) containing many names of genera that were later adopted by Linnaeus.[2] Binomial nomenclature was introduced in order to provide succinct, relatively stable and verifiable names that could be used and understood internationally, unlike common names which are usually different in every language.[3]

The application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature (ICZN) for animals and the International Code of Nomenclature for algae, fungi, and plants (ICNafp or ICN). Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences in the terminology they use and their particular rules.

In modern usage, the first letter of the generic name is always capitalized in writing, while that of the specific epithet is not, even when derived from a proper noun such as the name of a person or place. Similarly, both parts are italicized in normal text (or underlined in handwriting). Thus the binomial name of the annual phlox (named after botanist Thomas Drummond) is now written as Phlox drummondii. Often, after a species name is introduced in a text, the generic name is abbreviated to the first letter in subsequent mentions (e.g., P. drummondii).

In scientific works, the authority for a binomial name is usually given, at least when it is first mentioned, and the year of publication may be specified.

Etymology

The word binomial is composed of two elements: (Latin prefix meaning 'two') and Latin: [[wikt:nomial|nomial]] (the adjective form of Latin: nomen, Latin for 'name'). In Medieval Latin, the related word Latin: binomium was used to signify one term in a binomial expression in mathematics.[4] In fact, the Latin word Latin: binomium may validly refer to either of the epithets in the binomial name, which can equally be referred to as a Latin: binomen (pl. Latin: binomina).[5]

History

Prior to the adoption of the modern binomial system of naming species, a scientific name consisted of a generic name combined with a specific name that was from one to several words long. Together they formed a system of polynomial nomenclature.[6] These names had two separate functions. First, to designate or label the species, and second, to be a diagnosis or description; however, these two goals were eventually found to be incompatible.[7] In a simple genus, containing only two species, it was easy to tell them apart with a one-word genus and a one-word specific name; but as more species were discovered, the names necessarily became longer and unwieldy, for instance, Plantago foliis ovato-lanceolatus pubescentibus, spica cylindrica, scapo tereti ("plantain with pubescent ovate-lanceolate leaves, a cylindric spike and a terete scape"), which we know today as Plantago media.

Such "polynomial names" may sometimes look like binomials, but are significantly different. For example, Gerard's herbal (as amended by Johnson) describes various kinds of spiderwort: "The first is called Phalangium ramosum, Branched Spiderwort; the second, Phalangium non ramosum, Unbranched Spiderwort. The other ... is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia".[8] The Latin phrases are short descriptions, rather than identifying labels.

The Bauhins, in particular Caspar Bauhin (1560–1624), took some important steps towards the binomial system by pruning the Latin descriptions, in many cases to two words.[9] The adoption by biologists of a system of strictly binomial nomenclature is due to Swedish botanist and physician Carl Linnaeus (1707–1778). It was in Linnaeus's 1753 Species Plantarum that he began consistently using a one-word trivial name (Latin: nomen triviale) after a generic name (genus name) in a system of binomial nomenclature.[10] Trivial names had already appeared in his Critica Botanica (1737) and Philosophia Botanica (1751). This trivial name is what is now known as a specific epithet (ICNafp) or specific name (ICZN).[10] The Bauhins' genus names were retained in many of these, but the descriptive part was reduced to a single word.

Linnaeus's trivial names introduced the important new idea that the function of a name could simply be to give a species a unique label, meaning that the name no longer needed to be descriptive. Both parts could, for example, be derived from the names of people. Thus Gerard's Phalangium ephemerum virginianum became Tradescantia virginiana, where the genus name honoured John Tradescant the Younger, an English botanist and gardener. A bird in the parrot family was named Psittacus alexandri, meaning "Alexander's parrot", after Alexander the Great, whose armies introduced eastern parakeets to Greece.[11] Linnaeus's trivial names were much easier to remember and use than the parallel polynomial names, and eventually replaced them.[12]

Value

The value of the binomial nomenclature system derives primarily from its economy, its widespread use, and the uniqueness and stability of names that the Codes of Zoological and Botanical, Bacterial and Viral Nomenclature provide:

Problems

Binomial nomenclature for species has the effect that when a species is moved from one genus to another, sometimes the specific name or epithet must be changed as well. This may happen because the specific name is already used in the new genus, or to agree in gender with the new genus if the specific epithet is an adjective modifying the genus name. Some biologists have argued for the combination of the genus name and specific epithet into a single unambiguous name, or for the use of uninomials (as used in nomenclature of ranks above species).[19] [20]

Because genus names are unique only within a nomenclature code, it is possible for homonyms (two or more species sharing the same genus name) to happen, and even the same binomial if they occur in different kingdoms. At least 1,258 instances of genus name duplication occur (mainly between zoology and botany).[21] [22]

Relationship to classification and taxonomy

Nomenclature (including binomial nomenclature) is not the same as classification, although the two are related. Classification is the ordering of items into groups based on similarities or differences; in biological classification, species are one of the kinds of item to be classified.[23] In principle, the names given to species could be completely independent of their classification. This is not the case for binomial names, since the first part of a binomial is the name of the genus into which the species is placed. Above the rank of genus, binomial nomenclature and classification are partly independent; for example, a species retains its binomial name if it is moved from one family to another or from one order to another, unless it better fits a different genus in the same or different family, or it is split from its old genus and placed in a newly created genus. The independence is only partial since the names of families and other higher taxa are usually based on genera.

Taxonomy includes both nomenclature and classification. Its first stages (sometimes called "alpha taxonomy") are concerned with finding, describing and naming species of living or fossil organisms. Binomial nomenclature is thus an important part of taxonomy as it is the system by which species are named. Taxonomists are also concerned with classification, including its principles, procedures and rules.[24]

Derivation of binomial names

See also: List of Latin and Greek words commonly used in systematic names.

A complete binomial name is always treated grammatically as if it were a phrase in the Latin language (hence the common use of the term "Latin name" for a binomial name). However, the two parts of a binomial name can each be derived from a number of sources, of which Latin is only one. These include:

The first part of the name, which identifies the genus, must be a word which can be treated as a Latin singular noun in the nominative case. It must be unique within the purview of each nomenclatural code, but can be repeated between them. Thus Huia recurvata is an extinct species of plant, found as fossils in Yunnan, China,[28] whereas Huia masonii is a species of frog found in Java, Indonesia.[29]

The second part of the name, which identifies the species within the genus, is also treated grammatically as a Latin word. It can have one of a number of forms:

Whereas the first part of a binomial name must be unique within the purview of each nomenclatural code, the second part is quite commonly used in two or more genera (as is shown by examples of hodgsonii above), but cannot be used more than once within a single genus. The full binomial name must be unique within each code.

Codes

From the early 19th century onwards it became ever more apparent that a body of rules was necessary to govern scientific names. In the course of time these became nomenclature codes. The International Code of Zoological Nomenclature (ICZN) governs the naming of animals, the International Code of Nomenclature for algae, fungi, and plants (ICNafp) that of plants (including cyanobacteria), and the International Code of Nomenclature of Bacteria (ICNB) that of bacteria (including Archaea). Virus names are governed by the International Committee on Taxonomy of Viruses (ICTV), a taxonomic code, which determines taxa as well as names. These codes differ in certain ways, e.g.:

Summary of terminology for the names of species in the ICZN and ICNafp! Code !! Full name !! First part !! Second part
ICZN species name, binomen, binominal name generic name, genus name specific name
ICNafp species name, binary combination, binomial (name) generic name specific epithet
Unifying the different codes into a single code, the "BioCode", has been suggested, although implementation is not in sight. (There is also a published code for a different system of biotic nomenclature, which does not use ranks above species, but instead names clades. This is called PhyloCode.)

Differences in handling personal names

As noted above, there are some differences between the codes in how binomials can be formed; for example the ICZN allows both parts to be the same, while the ICNafp does not. Another difference is in how personal names are used in forming specific names or epithets. The ICNafp sets out precise rules by which a personal name is to be converted to a specific epithet. In particular, names ending in a consonant (but not "er") are treated as first being converted into Latin by adding "-ius" (for a man) or "-ia" (for a woman), and then being made genitive (i.e. meaning "of that person or persons"). This produces specific epithets like lecardii for Lecard (male), wilsoniae for Wilson (female), and brauniarum for the Braun sisters.[36] By contrast, the ICZN does not require the intermediate creation of a Latin form of a personal name, allowing the genitive ending to be added directly to the personal name.[37] This explains the difference between the names of the plant Magnolia hodgsonii and the bird Anthus hodgsoni. Furthermore, the ICNafp requires names not published in the form required by the code to be corrected to conform to it,[38] whereas the ICZN is more protective of the form used by the original author.[39]

Writing binomial names

By tradition, the binomial names of species are usually typeset in italics; for example, Homo sapiens.[40] Generally, the binomial should be printed in a font style different from that used in the normal text; for example, "Several more Homo sapiens fossils were discovered." When handwritten, a binomial name should be underlined; for example, Homo sapiens.[41]

The first part of the binomial, the genus name, is always written with an initial capital letter. Older sources, particularly botanical works published before the 1950s, used a different convention: if the second part of the name was derived from a proper noun, e.g., the name of a person or place, a capital letter was used. Thus, the modern form Berberis darwinii was written as Berberis Darwinii. A capital was also used when the name is formed by two nouns in apposition, e.g., Panthera Leo or Centaurea Cyanus. In current usage, the second part is never written with an initial capital.[42] [43]

When used with a common name, the scientific name often follows in parentheses, although this varies with publication.[44] For example, "The house sparrow (Passer domesticus) is decreasing in Europe."

The binomial name should generally be written in full. The exception to this is when several species from the same genus are being listed or discussed in the same paper or report, or the same species is mentioned repeatedly; in which case the genus is written in full when it is first used, but may then be abbreviated to an initial (and a period/full stop).[45] For example, a list of members of the genus Canis might be written as "Canis lupus, C. aureus, C. simensis". In rare cases, this abbreviated form has spread to more general use; for example, the bacterium Escherichia coli is often referred to as just E. coli, and Tyrannosaurus rex is perhaps even better known simply as T. rex, these two both often appearing in this form in popular writing even where the full genus name has not already been given.

The abbreviation "sp." is used when the actual specific name cannot or need not be specified. The abbreviation "spp." (plural) indicates "several species". These abbreviations are not italicised (or underlined).[46] [47] For example: "Canis sp." means "an unspecified species of the genus Canis", while "Canis spp." means "two or more species of the genus Canis". (These abbreviations should not be confused with the abbreviations "ssp." (zoology) or "subsp." (botany), plurals "sspp." or "subspp.", referring to one or more subspecies. See trinomen (zoology) and infraspecific name.)

The abbreviation "cf." (i.e., confer in Latin) is used to compare individuals/taxa with known/described species. Conventions for use of the "cf." qualifier vary.[48] In paleontology, it is typically used when the identification is not confirmed.[49] For example, "Corvus cf. nasicus" was used to indicate "a fossil bird similar to the Cuban crow but not certainly identified as this species".[50] In molecular systematics papers, "cf." may be used to indicate one or more undescribed species assumed to be related to a described species. For example, in a paper describing the phylogeny of small benthic freshwater fish called darters, five undescribed putative species (Ozark, Sheltowee, Wildcat, Ihiyo, and Mamequit darters), notable for brightly colored nuptial males with distinctive color patterns,[51] were referred to as "Etheostoma cf. spectabile" because they had been viewed as related to, but distinct from, Etheostoma spectabile (orangethroat darter).[52] This view was supported to varying degrees by DNA analysis. The somewhat informal use of taxa names with qualifying abbreviations is referred to as open nomenclature and it is not subject to strict usage codes.

In some contexts, the dagger symbol ("†") may be used before or after the binomial name to indicate that the species is extinct.

Authority

See main article: Author citation (zoology) and Author citation (botany).

In scholarly texts, at least the first or main use of the binomial name is usually followed by the "authority" – a way of designating the scientist(s) who first published the name. The authority is written in slightly different ways in zoology and botany. For names governed by the ICZN the surname is usually written in full together with the date (normally only the year) of publication. One example of author citation of scientific name is: "Amabela Möschler, 1880." The ICZN recommends that the "original author and date of a name should be cited at least once in each work dealing with the taxon denoted by that name." For names governed by the ICNafp the name is generally reduced to a standard abbreviation and the date omitted. The International Plant Names Index maintains an approved list of botanical author abbreviations. Historically, abbreviations were used in zoology too.

When the original name is changed, e.g., the species is moved to a different genus, both codes use parentheses around the original authority; the ICNafp also requires the person who made the change to be given. In the ICNafp, the original name is then called the basionym. Some examples:

Other ranks

See main article: Biological nomenclature, Trinomial nomenclature and Infraspecific name (botany).

Binomial nomenclature, as described here, is a system for naming species. Implicitly, it includes a system for naming genera, since the first part of the name of the species is a genus name. In a classification system based on ranks, there are also ways of naming ranks above the level of genus and below the level of species. Ranks above genus (e.g., family, order, class) receive one-part names, which are conventionally not written in italics. Thus, the house sparrow, Passer domesticus, belongs to the family Passeridae. Family names are normally based on genus names, although the endings used differ between zoology and botany.

Ranks below species receive three-part names, conventionally written in italics like the names of species. There are significant differences between the ICZN and the ICNafp. In zoology, the only formal rank below species is subspecies and the name is written simply as three parts (a trinomen). Thus, one of the subspecies of the olive-backed pipit is Anthus hodgsoni berezowskii. Informally, in some circumstances, a form may be appended. For example Harmonia axyridis f. spectabilis is the harlequin ladybird in its black or melanic forms having four large orange or red spots. In botany, there are many ranks below species and although the name itself is written in three parts, a "connecting term" (not part of the name) is needed to show the rank. Thus, the American black elder is Sambucus nigra subsp. canadensis; the white-flowered form of the ivy-leaved cyclamen is Cyclamen hederifolium f. albiflorum.

See also

Bibliography

Further reading

External links

Notes and References

  1. Book: Busby . Arthur III . etal . A Guide to Rocks and Fossils . 103 . 1997.
  2. Web site: Bauhin . Gaspard . Pinax theatri botanici . Kyoto University Library . 19 June 2016 . 17 October 2016 . https://web.archive.org/web/20161017200341/http://edb.kulib.kyoto-u.ac.jp/exhibit-e/b07/b07cont.html . live.
  3. 1959 . The Background of Linnaeus's Contributions to the Nomenclature and Methods of Systematic Biology . Systematic Zoology . 8 . 4–22 . Stearn . William T.. 10.2307/2411603 . 2411603 .
  4. Web site: binôme . Le Trésor de la langue française informatisé . Centre National de Ressources Textuelles et Lexicales . https://web.archive.org/web/20170606122907/http://www.cnrtl.fr/definition/bin%C3%B4me . 6 June 2017.
  5. Web site: Binomen . Wikitionary . 27 August 2022 . 11 April 2023 . 11 April 2023 . https://web.archive.org/web/20230411121632/https://en.wiktionary.org/wiki/binomen . live.
  6. Book: Reddy, S. M. . University botany: Angiosperms, plant embryology and plant physiology . 2007 . New Age International . 978-81-224-1547-6 . 34 . 13 November 2019 . 2 February 2023 . https://web.archive.org/web/20230202160908/https://books.google.com/books?id=SuQJeFkYoRIC&pg=PA34 . live.
  7. Book: Blunt, Wilfrid . Linnaeus: The compleat naturalist . 2004 . Frances Lincoln Ltd . 978-0-7112-2362-2 . 266.
  8. Book: John . Gerard . Thomas . Johnson . 1636 . The Herball, or, Generall Historie of Plantes /gathered by John Gerarde of London, Master in Chirurgerie; very much enlarged and amended by Thomas Johnson, Citizen and Apothecarye of London . . 14 January 2018 . 11 October 2017 . https://web.archive.org/web/20171011132117/https://www.biodiversitylibrary.org/item/33580#page/88/mode/1up . live.
  9. Book: Johnson . A. T. . Smith . H. A. . Stockdale . A. P. . 2019 . Plant Names Simplified: Their Pronunciation Derivation & Meaning . Sheffield, Yorkshire . 5M Publishing . 978-1-910455-06-7., p. v
  10. Book: Polaszek, Andrew . Systema naturae 250: The Linnaean ark . 2009 . CRC Press . 978-1-4200-9501-2 . 189.
  11. Book: Jobling, James A. . 2010 . Helm Dictionary of Scientific Bird Names . London . Christopher Helm . 978-1-4081-2501-4.
  12. Web site: Knapp . Sandra . Sandra Knapp . What's in a name? A history of taxonomy: Linnaeus and the birth of modern taxonomy . . NHM.ac.uk . 17 June 2011 . https://web.archive.org/web/20141018181831/http://www.nhm.ac.uk/nature-online/science-of-natural-history/taxonomy-systematics/history-taxonomy/session1/index.html . 18 October 2014.
  13. Book: Van Dyke, Fred . 2008 . Contemporary Issues of the Species Concept . Conservation biology: foundations, concepts, applications . 86 . Springer . 978-1-4020-6890-4 . https://books.google.com/books?id=Evh1UD3ZYWcC&pg=PA86 . 20 June 2011.
  14. Book: Peter J. . Russell . Stephen L. . Wolfe . Paul E. . Hertz . Cecie . Starr . The Linnaean System of Taxonomy . 2 . Cengage Learning . Species Concepts and Speciation . 2007 . 493 . 978-0-495-01033-3 . https://books.google.com/books?id=7F9UlGYGr0sC&pg=PA493.
  15. 2007 . General Principles of Taxonomy . Competition Science Vision . 10 . 114 . 764–767 . 20 June 2011 . Darpan . Pratiyogita.
  16. Book: Stevenson, Joan C. . Dictionary of concepts in physical anthropology . Greenwood Publishing Group . 1991 . 53 . 978-0-313-24756-9 .
  17. Web site: Dashwood . Melanie . Mathew . Brian . 2005 . Hyacinthaceae – little blue bulbs (RHS Plant Trials and Awards, Bulletin Number 11) . RHS.org.uk . Royal Horticultural Society . 19 February 2011 . https://web.archive.org/web/20110806123722/http://www.rhs.org.uk/getattachment/04d1dd16-01be-4c31-9510-8a081dfa23b0/Hyacinthaceae---Little-Blue-Bulbs-Bulletin.aspx . 6 August 2011.
  18. Bergmann . H. H. . Schottler . B. . 2001 . Tenerife robin Erithacus (rubecula) superbus – a species of its own? . Issuu . . 23 . 140–146 . 26 January 2018 . 7 May 2019 . https://web.archive.org/web/20190507175340/https://issuu.com/dutchbirding/docs/db_23_3_2001/26 . live.
  19. Michener . Charles D. . 1964 . The possible use of uninominal nomenclature to increase the stability of names in biology . Systematic Zoology . 13 . 4 . 182–190 . 10.2307/2411777 . 2411777.
  20. Cantino . P. D. . H. D. . Bryant . K. . de Queiroz . M. J. . Donoghue . T. . Eriksson . D. M. . Hillis . M. S. Y. . Lee . 1999 . Species names in phylogenetic nomenclature . https://ghostarchive.org/archive/20221009/http://www.botany.wisc.edu/courses/botany_940/05PhyloCode/papers/Cantino%2699b.pdf . 9 October 2022 . live . Systematic Biology . 48 . 4 . 790–807 . 10.1080/106351599260012 . 12066299 . free.
  21. Web site: HemiHomonym Database . herba.msu.ru . 17 November 2022 . https://web.archive.org/web/20150512143402/http://herba.msu.ru/shipunov/os/homonyms/index.php . 12 May 2015.
  22. Shipunov . Alexey . The problem of hemihomonyms and the on-line hemihomonyms database (HHDB) . Bionomina . 16 January 2013 . 4 . 1 . 65–72 . 10.11646/bionomina.4.1.3 . free.
  23. Book: Simpson, Michael G. . 2006 . Plant Systematics . London . Elsevier Academic Press . 978-0-12-644460-5., p. 552
  24. Book: Davis . Peter H. . Peter Hadland Davis . Heywood . Vernon H. . Vernon Heywood . 1965 . Principles of Angiosperm Taxonomy . Edinburgh . Oliver & Boyd . 8.
  25. ,, .
  26. James E. . Childs . Christopher D. . Paddock . The ascendancy of Amblyomma americanum as a vector of pathogens affecting humans in the United States . . 48 . 1 . 307–337 . 2003 . 12414740 . 10.1146/annurev.ento.48.091801.112728 . 13 December 2019 . 7 August 2020 . https://web.archive.org/web/20200807030223/https://zenodo.org/record/1234969 . live.
  27. Web site: Isaak . Mark . Curiosities of Biological Nomenclature: Puns . 17 June 2011 . CuriousTaxonomy.net . https://web.archive.org/web/20110519103654/http://www.curioustaxonomy.net/puns/puns.html . 19 May 2011.
  28. Geng . Bao-Yin . 1985 . Huia recurvata – A New Plant from Lower Devonian of Southeastern Yunnan China . Acta Botanica Sinica . 27 . 4 . 419–426 . 7 February 2011 . zh, en . 7 July 2011 . https://web.archive.org/web/20110707014652/http://en.cnki.com.cn/Article_en/CJFDTOTAL-ZWXB198504013.htm . live.
  29. Web site: Iskandar . D. . Mumpuni . D. . 2004 . IUCN Red List of Threatened Species: Huia masonii . IUCNRedList.org . . 19 June 2011 . 26 October 2012 . https://web.archive.org/web/20121026102204/http://www.iucnredlist.org/details/58303/0 . live.
  30. [#ICN2012|McNeill et al. 2012]
  31. Book: Schmidt, Diane . 2003 . Guide to reference and information sources in the zoological sciences . Westport, Conn. . Libraries Unlimited . 978-1-56308-977-0 . registration . 4.
  32. Book: International Commission on Zoological Nomenclature . International code of zoological nomenclature, adopted by the XV International Congress of Zoology / Code international de nomenclature zoologique, adopté par le XVe Congrès international de zoologie . The International Trust for Zoological Nomenclature . 1961 . 1961 . 1 . London . 11, 148 . fr, en . 10.5962/bhl.title.50303 . 29 March 2023 . 29 March 2023 . https://web.archive.org/web/20230329170250/https://www.biodiversitylibrary.org/item/107561#page/33/mode/1up . live., p148 Glossary
  33. (Web site: Article 5. Principle of Binominal Nomenclature | International Code of Zoological Nomenclature . 29 March 2023 . 29 March 2023 . https://web.archive.org/web/20230329164629/https://code.iczn.org/chapter-2-the-number-of-words-in-the-scientific-names-of-animals/article-5-principle-of-binominal-nomenclature/ . live.)
  34. (Web site: Glossary | International Code of Zoological Nomenclature . 29 March 2023 . 6 February 2023 . https://web.archive.org/web/20230206072152/https://code.iczn.org/glossary/ . live.)
  35. Web site: Sneath . P. H. A. . 2003 . International Union of Microbiological Societies . A short history of the Bacteriological Code . 20 June 2013 . The-ICSP.org . 24 May 2012 . https://web.archive.org/web/20120524070542/http://www.the-icsp.org/misc/Code_history.htm.
  36. [#ICN2012|McNeill et al. 2012]
  37. , Chap. 7, Article 3.1.2
  38. [#ICN2012|McNeill et al. 2012]
  39. , Chap. 7, Article 32.3
  40. How to Write Scientific Names of Organisms . Competition Science Vision . 20 June 2011 . 4 July 2011 . https://web.archive.org/web/20110704203742/http://www.journal.au.edu/au_techno/2001/oct2001/howto.pdf . live.
  41. Web site: Understanding and Learning Scientific Names of Species . Tan . Hugh T.W. . Tan . Kai-xin . Successful Learning, Center for Development of Teaching and Learning, National University of Singapore . CDTL.NUS.edu.sg . 20 June 2011 . 21 July 2011 . https://web.archive.org/web/20110721013443/http://www.cdtl.nus.edu.sg/success/sl43.htm . live.
  42. Book: Silyn-Roberts, Heather . 2000 . Writing for Science and Engineering: Papers, Presentations and Reports . Oxford; Boston . Butterworth-Heinemann . 978-0-7506-4636-9 . 198.
  43. [#ICN2012|McNeill et al. 2012]
  44. Book: Writing Guide: Language, Words and Format . Sydney, NSW . Macquarie University . 29 June 2011 . https://web.archive.org/web/20110629140234/http://www.gse.mq.edu.au/resources/guide/format.htm.
  45. Book: Merriam-Webster's Collegiate Dictionary . Merriam-Webster . Linnaean Nomenclature of Plants, Animals, & Bacteria . 2003 . 22a – 23a . 978-0-87779-809-5 . https://books.google.com/books?id=TAnheeIPcAEC&pg=PP28 . registration .
  46. Book: Nair . P. K. Ramachandran . P. K. Ramachandran Nair . Nair . Vimala D. . 2014 . Scientific Writing and Communication in Agriculture and Natural Resources . . 39 . 10.1007/978-3-319-03101-9 . 978-3-319-03101-9 . 11811479 . 2013953625 . 881314963 . 20 March 2023 . 28 March 2023 . https://web.archive.org/web/20230328005811/https://books.google.com/books?id=Uxm4BAAAQBAJ&pg=PA39 . live.
  47. Web site: Plant Nomenclature . https://archive.today/20121211140110/http://www.hort.purdue.edu/hort/courses/hort217/Nomenclature/description.htm . 11 December 2012 . Matthew A. . Jenks . Department of Horticulture and Landscape Architecture, Purdue University . Hort.Purdue.edu . 20 June 2011.
  48. Web site: Taxonomy – A Primer . Chris . Clowes . Peripatus.Gen.nz . 20 June 2011 . 7 August 2011 . https://web.archive.org/web/20110807091803/https://www.peripatus.gen.nz/biology/priTaxonomy.html.
  49. Bengtson . P. . 1988 . Open nomenclature . Palaeontology . 31 . 1 . 223–227 . https://web.archive.org/web/20141006071437/http://www.palass-pubs.org/palaeontology/pdf/Vol31/Pages%20223-227.pdf . 6 October 2014 . 22 August 2014.
  50. Orihuela . J. . 2013 . Fossil Cuban crow Corvus cf. nasicus from a late Quaternary cave deposit in northern Matanzas, Cuba . Journal of Caribbean Ornithology . 26 . 12–16 . 22 August 2014 . 27 January 2018 . https://web.archive.org/web/20180127004555/http://birdscaribbean.org/jco/index.php/jco/article/view/32 . live.
  51. Book: Page . L. M. . Burr . B. M. . 1991 . Peterson field guide to freshwater fishes: North America north of Mexico . registration . Houghton Mifflin Harcourt . 978-0-547-24206-4 . plate 52.
  52. Near . T. J. . Bossu . C. M. . Bradburd . G. S. . Carlson . R. L. . Harrington . R. C. . Hollingsworth . P. R. . Keck . B. P. . Etnier . D. A. . 2011 . Phylogeny and temporal diversification of darters (Percidae: Etheostomatinae) . Systematic Biology . 60 . 5 . 565–595 . 10.1093/sysbio/syr052 . free . 21775340.
  53. Book: Summers-Smith, J. Denis . The Sparrows . T. & A. D. Poyser . 1988 . Calton, Staffordshire, England . 978-0-85661-048-6 . illustrated by Robert Gillmor . registration . 114–115.